We researched this thoroughly in the early 2000s and came to pretty much the same conclusion even back then.
For us the main problem was the reliability of the mover. If enough panels face the wrong direction for long enough it is worse than facing the sun in a good enough fixed position all the time.
Our angle was to use a simple motor that runs with constant speed and use a special patented gear (called VIAX) to turn that simple movement into a sun following motion. The bet was that a still simple mechanical gear would be more reliable than complicated electronics.
In the end none of our simulations made us confident any moving solution wouldn't eat the profits.
I don't have the depth of experience with solar installations cited in your comment, but I have worked with systems that expected automated moving parts to continue to function in an outdoor environment. They all required near continuous maintenance.
Having a high level of cynicism regarding the utility industry, I wonder if the preference for moving parts is due to the requirement that only a large company with a constantly employed force of service personal can manage such a system. This would provide a certain amount of cost-of-entry that only large utilities could provide.
To quote what a utility company's compliance office once said to me, in a different context, "Only big companies can do that".
I have a fence that gets absolutely blasted with High Grade Texas Sunlight. It shortens the fence’s effective life by years — this idea is brilliant. Now I just gotta price out 80 sq m of solar panels.
EDIT: The fence gets at least 4 hours of direct sun in the winter; up to 7 in the summer. I can easily install 10KW of panels. I don’t have any way to store the power. I suppose I could build a giant Tesla coil and zap the neighbor’s dog?
A kWh of batteries costs about 200€ where I live, but if the panels cost a comparable amount to a normal fence you can probably just run the AC a bit cooler when the sun shines and use your house as a thermal battery.
Hold on, let me translate my stupid freedom units into Science™. My exterior house walls are already ... 30cm thick? That's 15cm of insulation + structure, a thermal gap, and then 10cm of stone facade. I only have to run the AC for a few hours at night, once the house warms up after a full day of sun. The only time of year I need "full AC" is during the high summer when the temps go above 40°C. What really kills me is that house is heated with propane, owned by a local monopoly, and the cost of propane has a 300% surcharge. The next time the HVAC packs up, I'm getting a heat pump, and adding solar panels (I only need a few); the savings in propane will pay for the HVAC/solar in a few years (in fucking TEXAS). The irony of this is not lost on me.
If you had a solar fence you could run the AC during max solar production for a couple of hours and not use it the rest of the day then. You might want to do the math on replacing the HVAC with a heat pump before it breaks, might be a good investment.
There's an enormous premium on heat pumps in the U.S. So, there's a manufacturer of heat pumps here, in Austin; they sell a heat pump for 1600$ in Australia (installed); but the same unit is 9000$ (installed) in Austin. Part of the difference is labor (about 1000$); the rest ... I dunno? The difference in cost in electricity vs. propane runs about 1500$/yr. My current HVAC unit is good for another 5 years, or so. I'll just wait it out.
Our research around the same time came to the conclusion of a sun tracker, with wind protection, would be the best option. The panels were very expensive (a 400'ish W panel that today cost $80 costed around $2,500-$3,000), so aiming for the absolute best performance for the panels was key.
The trackers fail sometimes, but I would say once a year or so. The electronics are not that complicated, and its reliability was higher than the motor itself. I remember calculating with fixed tracking of the sun (because you know were it is at all time) vs photocells that tell the motors were to move and by how much. The trackers win because when the day is cloudy the best performance is to put the panel flat and let it rest there (instead of tracking a sun that isn't there so the motor that day consume more energy that the panels generate), and with enough cloudy days the tracker outperform the fixed tracking by a significant amount.
It's not until recently, with 400W panels under about $500, that tracking no longer makes sense, at least in our latitude.
I always thought that someone would invent a cheap, simple, reliable, and passive tracking system. No need for sensors or intelligent electronics.
You have a simple motor that slowly tilts the array from facing East to facing West as power is being generated. The motor does not start until the panel is generating a certain amount of power. The motor runs at a fixed rate with a screw that takes about 7 hours to move the panel.
Once power stops (when the sun sets) weights on the opposite side slowly tilt the panel back to the starting position so it is ready for the next day.
The motor itself is a moving part that is subject to wear and tear and reliability and parts availability problems. Solar manufacturers and retailers are notoriously short lived and fragile (in terms of being able to survive changing conditions, like Chinese subsidies, price dumping, and now tariffs, not to mention technological improvements in module efficiency).
If you buy a bunch of commodity modules (panels) without moving parts, you generally don't have to maintain anything except maybe replace the inverters in a couple decades. And you can do that with any electrically compatible parts.
If you have a moving motor, suddenly you need to find all the specific parts for that particular motor, and hire a specialist crew to maintain and replace it, requiring a team with not just electrical knowhow but motor mechanics too.
That's largely incompatible with the US model of solar deployment we have now, which is largely "install and forget" using whatever equipment is currently cheap and available. It's very likely that the equipment manufacturer won't be around in a few years, and that installation company probably won't be for much longer. So any additional possible failure mode should be avoided.
At commercial or utility scale it might be different, but generally it's still more cost effective over time to just buy more modules to offset the less than optimal facing than to try to actively adjust their direction with moving parts. Modules keep getting cheaper. Motors, and more importantly, shipping and labor don't. Installing an overcapacity upfront is still cheaper than maintaining the trackers later.
A big, not so simple clock moving a heavy array in all weather conditions, having to deal with constant changes in humidity, temperature, thermal stress, potential salinity, wear and tear, lubrication, gears, jams, etc.
A large reason solar is winning out over wind is because the lack of moving parts drastically simplifies installation and maintenance. A solar tracker isn't as complex or high up as a wind turbine, but it's still much more complex than a standard roof or ground mounted array that doesn't move.
Trackers made sense back in the 70s and 80s when solar PV tech was still new, but now it's far cheaper to just add more module capacity than to try to dynamically optimize each module's facing through the day.
I agree that it adds complexity, but it seems to me that the minimum there is on the order of the joints on a lawn chair, a screw drive, and a stepper. Not exactly high tech and if sufficiently overspec'd not likely to fail even in extremely adverse conditions.
The thing is that most solar projects are commodity energy projects optimized for cost per watt, not necessarily reliability or efficiency (watts per area). We're not building them for the constraints of Mars bases or fancy spacecraft, just run of the mill generation.
Thus the tracker has to not just pay for itself, but be a better investment than simply buying more modules. The goal isn't reliability at any price, but cost effectiveness compared to making the project a little bigger and adding a few more modules.
Even with home rooftops (which have limited space), it's much cheaper to buy more premium modules with higher efficiency, or optimize their outputs with per module micro inverters or optimizers, than to mount the array on a tracker. With big commercial installations, there's even less of a space premium.
Trackers aren't just a one time upfront cost of manufacturing either, but an ongoing maintenance cost over the lifetime of the project. They get more expensive as less and less of the industry uses them and fewer parts and labor are available for them. They just can't compete with the Chinese dumping of cheap modules, which are so cheap now that almost all non Chinese manufacturers have gone bankrupt. So the industry is left with a glut of modules, which are probably just going to get cheaper and more efficient, while tracking technology and costs haven't improved anywhere near the same amount. It's all relative, and the trackers are losing big time.
Sure, as a science project with infinite funding, maybe you can make a super reliable one. In the real world, though, installations across the world have found them largely unappealing from a cost effectiveness standpoint.
I just spent 6 years living off-grid, running 5kw of solar, and 14kWh of storage. I setup a fixed array that I welded together myself. I could certainly see that tracking wasn't worth it even then.
However, in the off grid-setting I did discover some nuance. Sometimes you could really do with some power around sunset or sunrise. In the winter, being able to more reliably run my air-source heat pump at sun-up would have been very handy. Or likewise, some extra power to run the AC (which is the same device) in the early evening in the summer would have also been handy.
There were plenty of cold mornings when I was keeping an eye on the solar grafana dashboard, waiting for that hockey-stick moment when the sun swung into the right place!
I did consider the possibility of setting up an additional east or wast facing array to capture sun at the extremes of the day. Unfortunately that would have required its own MPTT charge controller, and would have just been more complexity in general.
Wouldn't it more reliable, day to day, to oversize the production during the sunniest parts of the day and then dump that into storage to use whenever you wanted, not only during twilight but whenever it was cloudy, freak weather conditions, etc.?
Some of that you can solve with dual side vertical panels mixed in. Obviously murders their output but you get it when it matters - on the shoulders of the day
I honestly don't think I would be comfortable off grid without 4x+ that size. Of course, environments vary so significantly that these numbers don't translate well when discussing them without geographic context.
My primary concerns would be consecutive cloudy days, and winters with very short days. While my actual heating/cooling needs are more mild than global averages, I think the combination of short daylight hours and increased heating needs makes off-grid solar unviable for climates closer to the poles, especially those not near sea level. I do think relaying on propane or wood for heating might make off grid viable for these locations, but that introduces questions of scalability and increased carbon footprint.
There is some argument that burning wood should be considered carbon neutral if the trees are replanted and used as a renewable resource (Carbon is released to the air, and then captured by the next tree in a cycle), but the land intensive approach wouldn't scale to meet the heating needs of a significant portion of the population. Additionally it ignores the carbon required to grow, harvest, process, and transport the trees or the alternative uses the wood might find elsewhere.
My point is for others to take their local climate into consideration before thinking that 5kw/14kWh would be enough for them to go off grid.
I think it entirely depends if you want a 'just works' solution or you're willing to adjust your lifestyle day by day based on availability of sunlight.
Merely a 10 watt panel in the Netherlands has been fine whilst camping for weeks, but obviously I have to severely compromise on modern life - 10 watts powers a lamp for a few hours in the evening and a phone charge each day.
I'm not sure it's rare to live about 45°N, where we start to see >9 hours of sunlight in the winter. The intersection of places that are both above 45°N and very cloudy (Portland, Seattle, London, Detroit, Copenhagen, Dublin, Vancouver) or in high altitude probably includes a good chunk of HN readers. Northern Europe gets down to about 6 hours of daylight in the winter. If you're in one of these regions, and you plan to use a generator to augment your energy needs, I don't think that's considered an emergency as much as a secondary power source. If one of your goals is decreasing carbon emissions then a diesel generator is going to set that back.
Other regions will have their own considerations, but the primary concern is balancing harvesting sunlight with heating/cooling requirements. I'm just encouraging people to do their own homework for their own situation when considering off grid. I've seen a lot of people under build and end up spending way too much to heat their homes in winter.
Sometimes the appeal is not in the "off-grid" itself, but in living in a remote location where having access to the grid is impossible or inconvenient (it does not have to be too remote either to not have easy access to the grid).
This is what I observe as a Realtor and living in a somewhat rural area - there are some people who like the idea of living the self-sufficient lifestyle, there are others who are convinced Armageddon is upon us and they are going to be ready, but mostly its because they found a beautiful location that speaks to their soul and the only way they can make it work is to use off-grid resources.
Taking time to cook elaborate meals is enjoyable if it isn't getting in the way of some other demand on your time. Living off grid you're probably going to have a lot less of those.
Living off grid means off the electrical and water/sewer/gas utility grid.
In almost no case does it mean off the internet now given Starlink; thus I think it’s silly to assume that a) being connected to the internet and b) having to admin all of your own utilities and associated equipment means you’re going to have fewer demands on your time. :D
Separately I love cooking as recreation, but don’t have much recreation time these days given my project-load (most of my projects being a form of recreation notwithstanding).
One of the reasons I am building a (mostly) off-grid place is because I like adminning infrastructure recreationally. I can’t wait to hook up my solar system to Home Assistant and Prometheus/Grafana.
I've been in solar energy as my primary vocation since the 1990's.
I've built solar cars, I've built solar panels, I've installed solar panels, I've designed solar trackers. I know this industry inside and out.
I'd never heard of an east-west array before (though I did experiment with one-cell-wide "crinolations" at 60 degree angles, did not find any value to using them but it was a different application where low-angle light wasn't a factor). I'd never thought of such an array on this scale, at this low angle, before.
I don't think most of the people reading this article quite understand that this is a completely different kind of array topology to flat-plate fixed-tilt, or tracking-based systems. Do yourself a favor, if you consider yourself intellectually curious, and if you came away from skimming this article thinking there's nothing new under the sun, read it again with a keener eye toward the novelty of it.
I have an east/west array on my roof, as my house is positioned with the front facing west.
In the winter it's outperformed by a south facing array (northern hemisphere) but in the summer the east array gets a ton of sun before midday, and crucially, it's getting a ton of sun when the temperatures are a bit cooler, so it performs very well.
I actually use this exact example when encouraging careful attention to paradigms where a fundamental variable is slowly but consistently changing.
It's essentially equivalent to a boundary on a phase diagram: Cost/Watt has fallen past a critical threshold, and suddenly this dramatically different approach just makes more sense.
Another interesting configuration is vertical bifacial panels aligned on North-South axis and interspersed with farming rows. Low-cost panels make it feasible and it doesn't much block agricultural production if the panel rows are spaced far enough apart.
I guess trackers really are an American thing? I’m in solar for ten years in The Netherlands, and I don’t think any utility scale fields use tracking.
For residential roofs east-west placed systems have been an option for the same amount of time. They are now gaining popularity in The Netherlands because of net congestion during midday.
Trackers are useless when the majority of the incoming sunlight is diffuse (as is the case where you live).
Trackers are useful when the majority of the incoming sunlight is direct (America has a mix but the western half and parts of the south have a lot of direct).
Trackers are essential when you use concentrated sunlight.
A tracker that doubles the amount of sunlight hitting a panel is not free, but it also makes the panel take up 2x the area, or more, to avoid shading its neighbor.
The thing people tend to forget about trackers is they offer this trade-off where you can trade shaded area for power per rated panel. When land is cheap and panels (or arrays, heliostats, power towers, etc.) are expensive, trackers make sense.
The reverse has been the case for the past ten years, and continues to get more true by the day. I doubt we will ever see the day return where land is cheap again and/or PV are expensive again.
Thank you, I went back and re-read after seeing you comment and I did indeed miss the big point here. I had been concerned that even if PV costs reach near zero, the fixed install costs would still limit future reductions on solar costs. Clearly not!
Looking at the graphs, the tracking arrays may have the added benefit of generating power in the mornings and evenings. If everyone builds non-tracking arrays, power during peak will become almost worthless if solar is a big part of overall generation capacity, so the economics might change even with panels being cheap.
Of course, just building 2x as many permanently tilted panels might also work.
Edit: the article actually addresses this: "[fixed setups] can pack 250% more installed power into the same space when compared to a single-axis array" - so even if only the power in the morning/evening has value, there is little reason to install tracking ones.
This is one of the areas where double sided panels reportedly win out. You can orient them to morning/evening light and they shed heat by convection better. Hot cells produce less electricity, which is why it’s difficult to construct Maxwell’s Demon from eg infrared-sensitized photovoltaics and band gapped radiators.
> If everyone builds non-tracking arrays, power during peak will become almost worthless if solar is a big part of overall generation capacity
During peak solar yesterday in California wholesale power was $5-6/MWh (<1c/kWh).
The CA grid is routinely over 100% renewables during springtime. The excess is handled by having a lot of batteries, exporting energy, and curtailments.
Yeah - you can’t talk about renewable energy generation without also considering when it is generated.
Then future price of energy will be incredibly time dependent. Finding a way to generate at a different time than everyone else - whether by east/west panels or time shifting with batteries or building a different kind of renewable generation is where all the big profits will be.
Demand isn't fixed in time either, though. Industrial processes that presently run at night to use cheap power will switch to daytime when it makes sense to do so. Summer mid-day also has the highest electricity demand all year in many places due to air conditioning, so arguably solar is addressing one of the biggest stress points.
Not an expert, but my understanding is that the challenge there is that a big cost in industrial production is the initial capital outlay for the equipment, and oftentimes to pay that back reasonably, you need to run the equipment nonstop. Also, some processes are challenging to stop/start.
This has been my understanding as well. But on the plus side, while you may run a machine all day, the price of cooling your equipment varies with the outside temperature and that is highly correlated with available renewable power. The AC units and diesel backup power are systems you buy and prefer to have idle. But not your press or data center.
"summer mid-day also has the highest electricity demand all year in many places due to air conditioning,"
Peak electric demand is 3-7pm in the summer. You might think you could then just set panels to to optimize for afternoon, but especially in winter, you get a big peak between 6-9am.
In the West, the cost of labor makes that unappealing. From a DIY standpoint it'd still be a pain. Those things are heavy and usually require at least 2 to 4 people to install or move. It's not something you'd want to do regularly if avoidable.
I imagined then being panels on like a hinge that you like unbolt, tilt a little and then bolt down again. I didn't know it would take multiple people to do it.
Yeah, you could maybe design something like that. It'd still be quite a lot of work to go through all the panels one at a time every few months, though. And doing the math to remember what angle to point them at would be annoying and error prone.
Totally depends on the location. Say, Northern Europe has traditionally very little AC (changing thanks to dual use heat pumps) and the energy use naturally peaks at the depths of the winter.
It already is on wholesale markets - in the UK you can get on Agile Octopus which gives you half hourly prices. When there is a glut of renewables on the grid you can end up being paid to use energy.
This highlights the need for grid scale storage (be it batteries, pumped hydro or something else) to balance Solar PV, and to bridge gaps when the wind isn't blowing.
Power during those lull periods will get expensive, and that’s likely to result in some farms with permanently tilted panels that prioritize those periods over peak overall production.
Space is cheaper than maintenance and breakdowns in many cases.
but, 70% of MY! yearly households electricity consumption is literally into [PV!] hot water. Hot water tank is cheapest energy storage device on planet. and i do not have to worry to shower in noon, i can just charge my water tank during day, even when im not home. and use hot water in evening. for very little price - no need to use heat pump, resistive heater is super cheap. hot water tank can be made even DIY to lower price even more.
utility charges me so much for electricity that even tho i payed for 15 kWp roof mounted east west system literally literally ORDER OF MAGNITUDE more than prices showed in that article, AND i still save money by not buying electricity from grid !
that how much utilities are charging us, yes they need to manage all those wires, manage power plants, etc. i do understand where that cost comes from, but still, solar in residential is so cheap that installing PV on roof and directly consuming it will save you money.
So for industry/ manufacturing there will be extremely high incentive to add PV + battery even when it wont cover 100% of their loads. utility+ onsite PV+battery.
Again, back to my hot water system, 80% of year i am 100% "off-grid" for hot water [PV!]. even on days it is cloudy ! And 99%-0% of PV rest of year... And from april to October my electricity draw from grid is almost zero.
so whole residential USA can be essentially "off-grid" huge part of year with just small battery, your tv, notebooks draw almost nothing over the course of the day compared to your energy need for hot water. and less residential is on grid, easier it is to manage electricity for other sectors of economy.
this contraption from ETH Zurich can store iron/iron oxide to generate hydrogen, without storage loss! for years, without compressing hydrogen and without other cons of "standard hydrogen storage. essentially it can be thought about as hydrogen storage - it can "store" 10s of megawatts inside of a standard basement. - [https://ethz.ch/en/news-and-events/eth-news/news/2024/08/iro...]
and you do not need to make electricity from that hydrogen, you can heat your house directly with hydrogen, just by replacing 30$ burner in your existing furnace!
so you complain about "peak" power excess, and i say and i show it to you that this "peak" solar power can be used to charge that extremely cheap storage device in summer and expend that storage over winter for heating house and making hot water. when sun is not shining.
and again, calculate how much kWh is your need for heating and how much is for hot water and you can clearly see that extremely huge part of current residential energy need can be either "onsite off-grid" with this contraption + small LiFePO battery or to be on-grid and take only small loads like tv, notebooks from grid and having heating + hot water "onsite off-grid". and most importantly cheap.
ratio of kWh for your heat and for your other appliances ! ! ! !
So essentially we can charge our heating system in summer, store energy WITHOUT LOSS until winter and heat with that energy in winter. right now!
just sketch/draw for yourself timeline containing - PV + storage contraption in that link + small LiFePO battery. and you can see how huge part of energy we do not really need to draw from "grid".
small towns can even make their own shared storage, prices for SEASONAL energy storage are even lower then current prices for electricity drawn from grid....
So this physical, economical actual contemporary possibility makes me mad every time i see just another youtuber or other kind of influencer, post about just another battery technology promising who knows what, in who knows what timeframe.
we do have energy storage technologies capable of providing citizens of USA with clean energy RIGHT now, RIGHT here. for whole year, day and night. without buying one drop of oil from tyrants, dictators who literally literally kill people right at this moment.
I didn't read your entire comment (sorry), but wanted to support your water tank statement.
I live in an area with frequent, often day long power failures during winter storms. So my house is designed around that.
When I bought a new hot water tank, I spent a little extra for the super insulated one. The result?
I can take a shower during a power failure, and still another not as hot 24 hrs later! When you consider that the first shower injected cold water into the tank, that's fairly impressive.
On long power failures, on the third morning I can even take a lukewarm shower, with no cold water at the shower (I have individual hot/cold controls). This is far preferable to a shower at 5C water temp (from my well in winter)
And where did any eacaped heat go? Why... into my house! Surely not a loss.
Yeah, similarly with insulation / good building practices, my house can lose power in coldest of days and i do not have to put on hoodie for 2 days. (not heating by other means like wood, which i do not have) it is not big house tho. it is insane to me that in country where there are tornadoes, hurricanes, wildfires hundreds of times per year, we do not do this / build like this by default.
In europe, there is possibility to be on "energy spot prices", essentially utility will charge you energy market prices. today price at noon was almost zero. last Sunday, prices were negative - they literally pay you to draw from grid. but at evening, price can be quite high.
so having simple time relay / or more complex minicomputer directly reading energy market prices and switching loads can even earn you some money. it is not money making business but overall price can drop significantly. it is also an economic incentive to buy battery storage and actually got to paid it off.
Enabling citizens to do good thing is underrated.
people with "standard" contract are essentially subsidizing industry, corporations which have cheaper electricity because of bundling with residential customers. which makes weird and complicated incentive structures. essentially anti-market behavior in country which boasts itself in "capitalistic" structures... and slowing adoption of renewables, because it looks like they are more expensive than they actually are.
I read, and appreciated, your entire comment - thank you.
You describe a simple and elegant solution to some portions of these problems and what you are doing with your hot water "battery" is smart.
I am forced, however, to ask:
Where do you live and how large is your family ?
My suspicion is that you do not live in the United States and your family is relatively small ... ?
Modern, "first world" ("global north" ?) 21st century homes do not match your model in a number of different ways:
- Unlimited, temp stable hot water comes from a tankless water heater. People don't "run out" of hot water anymore.
- A family - even a relatively small family - runs a 30A dryer daily. Our family of five runs it 1-2x daily.
- Many, many people now have electric cars and some households have two of them.
- I agree that laptops and phones and personal electronics are a rounding error here but microwave ovens, toasters, coffee percolators, etc., are not - and people use them. I will note in passing that both our dishwasher and our microwave oven require 20A circuits.
I am optimistic that we (as a society) can satisfy these demands with solar power - I just want to make sure you appreciate just how much demand for electricity a modern US household has.
FWIW, we are planning on going entirely off-grid, purely solar with lifepo batteries, in the next 18-24 months.
Americans basically live like energy is unlimited, free and has no side effects, the rest of the world doesn't have that chance, last time I checked the average US household used anywhere between 3x and 4x more electricity than the average EU household
They tend to prefer huge houses with relatively complex designs (less optimal in term of area/volume ratio) / poor insulation, they make up for it by relying on tech for heating/cooling pretty much year round.
Your tankless water heater is a good example of something that is completely inadequate for solar setups, they draw insane amount of energy over very quick period of time. But I think that's the core of the issue, if you want to keep all the nice things modern American houses have you're going to need a lot of money and a lot of sun. On the other hand if you're a bit more frugal, with so called "passive house", you can get by with a much smaller setup.
> I will note in passing that both our dishwasher and our microwave oven require 20A circuits
And a tankless heater will need 5 times that, unless you're using gas but I wouldn't count that in a "modern first world 21st century home".
"Americans basically live like energy is unlimited, free and has no side effects ..."
Agreed - and guilty as charged which is why we're switching entirely to solar.
(I will also note that my household "cheats" by living in California where we need relatively little heat and do not even own an air conditioner so our path is, perhaps, a bit easier)
My main point is that whether you're a frugal EU council house or a profligate Texas McMansion, we - all of us - will continue to invent new demands for energy and continue to trend towards more energy used per person per unit time.
Therefore, if you're looking ahead to deployment of solar resources you should be realistic about that trendline.
> we - all of us - will continue to invent new demands for energy and continue to trend towards more energy used per person per unit time.
I'm personally in the process of designing my house and I'm going for maximal energy efficiency: 38cm thick brick walls + 20cm thick rock wool insulation, basic rectangular shape, 80% of the windows to the south, triple pane, heat recovery unit coupled with a air/earth heat exchanger to avoid needing a resistance to pre warm the air in winter, heat pump water heater, catalytic wood stove
Although I would agree that overall people don't give a shit and I probably am in the minority
> Your tankless water heater is a good example of something that is completely inadequate for solar setups, they draw insane amount of energy over very quick period
I know nothing about any of this, so please educate me for the good of us all - wouldn't this logically be a use case for a battery? IE: solar (or wind or whatever...) feeds a battery that feeds the tankless water heater. As a layperson, it would seem to me like the issue isn't generation but rather availability at the moment of demand - which would be the case in any kind of micro generation, right?
"Ordinary European household" will change even lower :
Crisis of 2008 made EU to think about resiliency so they asked all kinds of economists, physicist, other science people what should be done to provided that and one of those things implemented was building energy efficiency directive
[https://energy.ec.europa.eu/topics/energy-efficiency/energy-...]
which progressively increased demands on building sector to provide citizens with "low energy" housing. and currently most states of EU have requirement to build houses where defacto energy need for yearly heating of a house is lower then energy yearly demand for hot water (hot ater can not be lowered significantly without heat pumps - COP3+)
You should still probably add a hot water tank to that setup, just put it in front of the tankless heater. It is a like a battery that is 100x cheaper. You could go high tech and run the tank heater when you have solar excess, or low tech and just put it on a timer to run for a few hours around noon.
Everyone should calculate how much is consuming in kWh, recalculate gas into kWh, wood into kWh, propane into kWh.... then it starts making sense for ordinary people. Even for how much energy leaves their house. To use kW / kWh for everything.
" 1)- tankless"
more than half of USA has water tanks. both water tanks and tankless heaters have expected working life, after taht they have to be replaced either way.
Tankless heaters are more efficient if you think only about AMOUNT of energy, but water tanks are there to lower your PRICE of hot water. (or spread load over longer time for usecase as your offgrid) So yes, with tankless you are doing best in standard "old" grid situation, where price for electricity for customer was same throughout day, (some tariffs can have different price in night) (or when you ask Ask This Old House)
AND with PV! on roof and tank in basement, households are providing service for utility because A) they do not export solar at noon, they are putting that energy to water tank, B) they do not import energy during evening peak hours. so less generation / "base load" needed to exist, to operate, service, manufacture.
but there are new things like solar export which will change grid. and people have to adjust, or they can just install expensive battery paid with gov subsidies (by "utility")... residential customer can either use cheap electricity during day to heat water tank or utility can charge for "stabilising" of grid multiples of that price.
so customers incentive should be to have hot water from PV on his own roof. and when they do not have enough solar energy they can charge rest from grid. and lowering need for importing from grid by 80+% per year... for hot water energy.
"2)dryer "
how much is that kWh ? can it run during day when there is availability of PV ? Or atleast one of those cycles can run during day?
" 3) electric car "
I am one of them but unfortunately i am working from home and have nonstandard schedule (20-45 miles per day + once per week trip to buy groceries in town 130 miles ) so i can charge my car from PV, not many people can do that. but they can have water tank on PV and car on grid... or if they use one car only sporadically, then that one can maybe charge from PV ?
my electric car can be charged by 2kW from standard outlet for 10 hours to add 62 miles of range, in summer when i do not want huge loads or i can connect it to faster charger. one car takes daily roughly same amount of energy as 2 people need for hot water...
"4) appliances "
how much is that kWh ? starting current can be higher, sustain power can be lower. starting power can be lowered by using "starter circuit" - bunch of capacitors connected to motor, but lot of motor apliances already have it. coffee percolator is essentially water tank so you are already doing it ;) 20A is not much, some appliances can be connected to 240v if it is available. or adding more circuit breakers if you have slot for them, and spread loads between circuits.
"5) rest"
not waste, save, use on site first, then grid. most people live grid first... i do not mind grid
im not saying everyone should go off-grid, because high-rises can not. but everyone who can, should atleast be able to have 5-10 kWp PV on roof just for hot water, and it can be used in emergency for other things (not necessarily same lifestyle). such small pv + hot water tank as a predictable load connected to well sized PV can make PV be payed sooner. and having connection to grid, with possibility of getting payed for export of excess in future for powering highrises...
my system got payed in 6 years because i use a lot of energy directly. lifetime of inverter is presumably 10 years and panels 20 years so i have presumably next 4 years energy for free. then i have to replace inverter,... if those devices last longer, saving is even bigger.
I wonder if you could make a DMD [1] where instead of mirrors the tilting part is tiny solar panels?
The panels would only have two positions, but you could install half the DMD devices so that the two positions are south and southeast, and half so they are south and southwest.
You could then have half your panels southeast and half south in the morning, all of them south midday, and have southwest and half south afternoon.
That would get you at least some tracking and it should be mechanically a lot more reliable than the systems that move large panels.
DMDs were designed for use in video projects, where they have to move the mirrors more times in 4 hours of video than a solar array would need to move the panels in 1000 years.
Too much complexity and maintenance. Solar panels are dirt cheap, and with fixed mounts, zero maintenance. The rack you mount them on costs more than the panels.
The only reason I can see for added complexity is if you're space constrained, and in almost all cases, not cost efficient.
We have an east/west roof with solar on it. It is less efficient than our previous roof which was pure south - but it smooths out the generation and gives us more electricity in the evening.
When panels are cheap what about vertical mounting? Less susceptible to hail and snow. And maybe placed north-south, to maximize production in morning and evening when it's needed most.
The article seems to be mostly about grid scale solar. Of course an increasing amount is private or domestic solar installed on e.g. building roofs or wherever there is space.
When cost drops low enough, any surface with any exposure to sunlight is in scope for installing solar on if it can yield more energy than the cost of installing solar on it. It stops being about what is the most efficient and starts being about if the surface is good enough to provide a decent return on investment. Maximizing that ROI is complex but it boils down to getting more value out of the installation than goes in.
Solar doesn't even have to be in panel form. Some office buildings now have windows that double for solar generation. A thin transparent coating does the job. There are roof tiles that double as solar panels. Aptera makes electric cars with integrated solar panels. These are curved glass panels that are manufactured to fit the profile of the roof and hood. It's also possible to print organic solar cells directly on plastic rolls. No glass involved. Or panels. Those are less efficient but you can integrate them on all sorts of surfaces. A lot of that stuff is still emerging technology. But especially organic solar printed on plastic rolls could end up being very cheap to produce. And very light.
Domestic solar is a rapidly decreasing fraction of total solar deployments [1]. Not because it is not growing exponentially, but because grid-scale is much more exponential with no signs of that changing.
“When cost drops low enough, any surface with any exposure to sunlight is in scope for installing solar on if it can yield more energy than the cost of installing solar on it.”
I don’t see the logic? As panel prices drop, installation costs start dominating overall cost of energy produced and so economic pressures will be on simpler and simpler PV installations. Laying a panel almost flat on the ground amongst thousands of others will be a cheaper process - both initially and in terms of ongoing maintenance - than anything that involves sending workers up ladders or cherrypickers attaching and wiring a panel onto the side of a building.
So grid scale will start to dominate over domestic or “novelty” (e.g. floating panels on reservoirs) and simpler and simpler approaches to installation (like removing tracking) will become attractive.
These effects are already apparent. Basically the opposite of what you’re predicting?
You use the surface area you have. Most people simply don't have a lot of ground to put solar on but they might have a roof. Also, you don't just need solar panels but also the wires to where the power is needed. On the roof of the building where you are using the power is just about as close as you can get with that.
Otherwise it's a simple economic equation. If installing solar saves enough money such that you end up with a decent return on investment then making that investment is more optimal than not making that investment.
That's why most of Australia is running on rooftop solar when the sun is shining. The US is a bit behind on that mostly because the US has a lot of rules stacked in favor of grid providers. Australia used to have that and eventually the grid providers lost that battle.
Installation costs dominate largely due to one-off things (getting the contractor/customer, roof access, adapting to bespoke roof layout, etc) which are disproportionately larger for smaller installation sizes. However for new construction those things are essentially free. So yes, I’d absolutely expect that solar will be added during larger rebuilds. But that is not an effective way of “deploying solar”
Grid scale solar benefits from bifacial cells in a vertical orientation just as much as home scale solar - it dramatically improves winter production and extends the production of the spring/fall day a few hours earlier and a few hours later.
Not only does it increase overall production, currently one of our biggest challenanges is transport and distribution, and having some of that power in the of-hours instead has more benefits than power total alone.
I’ve seen some YouTube videos of people making solar fences with bi-facial panels. If I recall correctly on the one I was watching, they were going for morning and evening production and faced them east/west. One side would get the morning light then the other the evening light.
Yes ! Triple price of PV panels to buy "ceramic glass print" PV panel with eye pleasing pattern / stealthy photo on it and you can have facade or fence made from PV panels, there is drop in generated power from 10-50 % depended on pattern, color used.
Price per panel not price per install ! ! ! And subtract need to buy materials used for that purpose before.
It’s mentioned in the article that sunlight from near the horizon passes through a lot more atmosphere, which attenuates the light so much that you might as well not bother with the panels.
That depends on your latitude, how dear land is, and how close to breakeven your application is.
For a lot of applications, panels are so goddamn cheap now and breakeven happens so fast that "Just buy twice as many panels" is the best solution to any problem that doesn't involve land area. Winter production in a snowy/leafy climate at a latitude tilt, though, is the exception to the rule; Production is so impaired without regular maintenance that twice as many panels is not very helpful. But set those panels vertical, at a range of orientations, and snow/leaves stop being an issue, you get sizable exposure with the sun low on the horizon, the maintenance requirement goes away, and you get an appreciable amount of power earlier in the morning and later in the afternoon, you just don't get quite as much at noon.
I'm pretty sure by north-south they are talking about the direction the panel lies in, i.e. the faces point east/west.
But even under your interpretation, you aren't always right. If you're far-ish north of the equator you want south facing panels (and the reverse) and if the cells are cheap enough it makes sense for those panels to be bifacial, with one side permanently facing away from the sun, to get a bit of extra energy from ambient light. Especially in winter when there is less sun (so energy is at a premium), and highly reflective snow resulting in a lot of ambient light.
Trackers tend to suffer from mechanical failures. Even 15 years ago, there was only one way to make money out of solar panels: Install them and forget them. If you need to waste time and money on the installation then the small profit vanishes really quickly. I really don't know how those companies convienced the investors for trackers.
I really like that how it's possible to put bifacial panels vertically along north-south direction to get solar power off peak. It should reduce cost of installation (it's basically multiple rows of fences), snow removal and cleaning. Washing down panels from dust could probably be automated too and if you build them up a bit higher you could have a meadow underneath or even a field of something. Hail should also be probably less of a concern. You need more land of course but it's still awesome.
Many trees don't but lots of smaller plants do tilt their leaves towards then sun and can be seen easily in a timelapse. And also like the other guy posted, sunflowers famously follow the sun.
I used to work on solar power plants and solar tracking technology back in the late 2000s. Even back then, I remember frequently discussing that "eventually panels will be cheap enough that we'll just wallpaper the world...". It's really nice to see that coming true.
I wonder if you could make deployment / installation even cheaper by making big “rolls” of panels and unfolding them directly on the ground. No ground pillars of any kind.
If you built a zigzag pattern into the panel, possibly with some ultra-cheap alternating cylindrical ground support, you could easily deploy them in this East-West configuration.
You will have to drive some pillars into the ground to secure them anyway, but it might be much faster and require little labor.
The graphs show huge price drops over the last ten years. I wonder, how different does the price look for residential solar panel installations? Presumably the labor will start to dominate the cost if it doesn't already?
Labor does dominate. Panels are dirt cheap and inverters, while they haven't come down in price that much, seem to still cost less than half of the price of the panels per watt.
One cool observation of an grid wide advantage is that single axis really normalize the power curve per panel. There are many reasons way more consistent production would be better.
I am curious if just having more fixed panels normalize production at scale
I'm probably not thinking this through, so go easy, but why wouldn't tracked panels also produce a normalized power curve? My assumption behind the question is that they follow the same track as Sol every day, which doesn't vary at least year-to-year.
No i am viewing from there graphs of power over the day not over the year.
Untracked panel production has a sharp peak at noon and that rises and falls pretty sharply before and after that. Maxing/stable between 10am - 2pm
Single Axis flattened that curve up very heavily so you were producing at or close peak production for much longer. 8am - 4 pm
The double axis seemed to just get slightly high magintude in power compared to the single axis which is good but definitely marginal.
The question would be is if you have an array of fixed panels can you fixed them in a way that flattens out the peak production but provides a more level and less peeking production for the grid as a whole. This is really important because its much harder to turn off/disconnect solar than other forms of power. The grid has to be sure it doesn't overcharge or undercharge the grid. If you do either you'll deviate from the target 60Hz (US) you can damage a switching and transformer infrastructure.
A less peeky supply is more predictable generally speaking and gives you more time to react to changes in the grid. The per cost question would benefit from answer this because it might make sense to install more panels in a fixed position that is not maximally optimal at an individual level but is maximal for the overall grid health. That investiment in deployment is worth it to make now because you'll never want to change it afterwards.
I always see articles about the decreasing cost of solar, but where are these costs collected from? Is it just not available at a consumer level? Maybe I missed the sources in the article somewhat...
There are lots of consumer facing companies selling panels. You'll need to buy in bulk (generally a pallet), but you can easily get them for $0.30 / watt.
Compelling analysis. But if hail damage is the primary concern, tracking seems like an X/Y solution. What about eg anti hail netting that can be rolled out when the weather forecast predicts hail? It seems to me like a middle ground might be automated deployment of hail protection, which by definition has lower aero loading than what amounts to a big semiconductor sail.
anti-hail netting? you must not be from somewhere that receives a lot of hail. hail punches through solid coverings at the right size. if it's not the right size, then it's not that damaging.
netting? ha! thanks for the funny visual so early in the morning.
Hail punches through solid coverings because they are rigid. They nearly instantaneously stop the hail which means they absorb all of the kinetic energy of the hail very quickly. They don't have a good way to dissipate that energy as rapidly and it goes into breaking the structure of the covering.
Nets are flexible. The energy of the collision goes into accelerating the net at the point of the collision. The net can quickly spread that energy into accelerating the surrounding areas of the net and so on. Unlike with a rigid cover this is not nearly instantaneous, so you don't have all the kinetic energy of the hail being poured into the net at once. That and the ability of the net to rapidly spread energy means that you don't get enough energy anywhere to break the net. It just stretches as it decelerates the hail.
You can see how this works by watching a soccer game and observing how the nets at the goals stop balls. Hailstones that weigh more than a soccer ball are extremely rare, as are hailstones that are falling faster than many strikes and penalty kicks in a professional soccer game, and you don't see many soccer balls breaking through the net.
People have calculated how fast a soccer ball would have to go to get through the net and found that it is over 220 mph. The largest recorded hailstone is estimated to have had a terminal velocity of 168 mph, based on size, mass, and atmospheric conditions. That hailstone had about 16% more kinetic energy than a 220 mph soccer ball and so might have broke the net, but soccer nets are by no means the strongest nets that can made. And remember that was the largest hailstone ever recorded--we are talking a once in decades event.
I think a hail net would be feasible for some cases. Golf balls break solid coverings too (and windows, car roofs, etc), but we have nets for them.
You want high tensile strength and some level of flexibility/elasticity to absorb the hailstone energy over a greater-than-zero distance. Or to shatter the hailstone well above the solar panel.
Probably too light-blocking to leave up continuously, and maybe awkward and failure-prone to deploy automatically.
So insurance is probably more cost-effective for most installations.
I agree with your implicit point that the key question is probably cost effectiveness compared with insurance. However, in the context of the OP, insurance premiums in hail-prone regions was listed as a prime reason why single-axis-tracking panel installations are, in some regions, probably still a better bet at grid scale.
The point I'm trying to make is just that there are a lot of off-the-shelf (or nearly so) hail protection strategies that seem like they might have better economics than single-axis-tracking installations, which might improve the cost effectiveness of a fixed panel installation to the point where, even in hail-prone regions, it might be doable.
To be clear: anti-hail nets are already a COTS product, just not for this application (as far as I'm aware). Nets are just really, really good at absorbing kinetic energy. I mean, that's effectively what kevlar ("bulletproof") vests are made of -- netting with a very small cell size. But it seems to me like some kind of roll-out kevlar or dyneema netting could be really effective at protecting panels, though I think you'd need some kind of better strategy for safely dispersing the hailstones after they were caught, so you don't end up with a huge collection of hailstones on the net.
I agree that there's probably too much light blocking to leave them up continuously, and I'd also be worried about UV damage. But remember that the comparison here is to single-axis-tracking installations; I think automatic deployment of anti-hail netting could easily be made at least as reliable as the tracking system, if not significantly more so. Maintenance and testing would also be very cheap in comparison, since you could do it at night (ie without affecting power production), and damage to the protection system could be repaired without taking panels offline.
The more I think about it, the more I'd be interested in seeing it deployed.
Anti-hail netting is definitely a thing (protecting cars or fruit trees), for the reasons you state. Even big hailstones are rather slower than fast golf balls.
Hail damage at car dealerships in my area is so expensive that the dealers have added coverings for the lots (pretty sure highly encouraged by the insurance companies), and they are most definitely not nets. Nets would have been cheaper, so that should say something about their effectiveness (or not)
Hail protection nets are a COTS product. Full stop. Properly-designed nets are exceptionally strong; that's why we make "bulletproof" vests out of them (that's all they are, just a fiber net with a very tight weave).
Just because your local car dealership(s) didn't opt for hail protection nets isn't on its own evidence for or against their effectiveness. There are a great many factors that go into such a decision and, unless you were privy to the decisionmaking process itself, whether or not nets were considered -- much less their effectiveness -- is pure speculation on your part.
Sorry, I don't get the joke. Nets can be pretty strong. Is it because there's a lot of hail at sizes big enough to do damage but too small for a net to catch without deep shadows?
i used standard chain link fence on top of my small greenhouse and it works even with such big "holes", no mechanism, just manual labor but needs good forecast which can be issue.
I'm intrigued. Can you expand more on this? Why does it work? I guess because the hail is rarely coming straight-on at the holes and instead makes more glancing blows off the wire?
In any case I think it's a perfect example of a good hack. Original out-of-the-box thinking producing an effective but unconventional solution. Chapeau bas!
i saw chicken wire used for something unknown to me on top of old 1800s greenhouses in France. it was not used for hail because it was resting directly on top of glass. i do not know what it was there for.
but hail and flying debris i got past few years is so big and so frequent that im not sure chicken wire will do the job.
a lot of gardeners use shading cloth for lowering sun light intensity. but that is not always enough to withstand hail.
A lot of times there is multiple pieces of hail stuck in one hole. some just bounce off.
i have PV on roof and not had issue with that. but i had few broken glass pieces of greenhouse glass. even tho it is on same property. it is glass-glass bifacial, i did not do it for back light but for longevity, i saw too many plastic backing tear off, or delaminated or how to call it. so i did not want that. and im not sure if that is also factor in not having broken PV.
doing it on huge PV areas should atleast be by my feeling too much of hassle, investment.
But some people mentioned in other comments small arrays of, if i remember correctly, 5kWp. so that is roughly area im doing it on. so in those small arrays it can be done manually.
well, makes goats not eat precious plants so if it can withstand them, then hail will be ez. XD
(neighbors goats. i do not like animals, too much worry and work around diseases. there are tens, some years even hundred millions of chicken burned because of avian flu, pigs have african swine fewer,.... no thank you, corona cave bats of 2019, was enough for me...)
This might be a dumb question but what about _compliant_ joints that expand and contract when warmed up by the sun? You can have any expansion multiplied such that minor changes in length are sufficient to track the sun in a meaningful manner.
I don't understand how east-west arrays differ much from just a flat area. At the end of the day, don't they capture all sunlight in some large square? The east-west array only captures a bit differently around the outer edges. Can somebody explain? Is solar panel efficiency that dependent on incidence angle?
The article fees disingenuous, flat panels collect the maximum sunlight from a given area of land and require fewer panels than the arrangement shown. Angling them helps the rain wash them and reduces the amount of mounting brackets unless you’re laying panels flat on the ground. Similarly total KW over the day isn’t why tracking mounts are so common instead it’s the increased value of electricity in the mornings and evenings so the actual economic benefits != total kWh.
However, the bit where it’s talking about increasing the angle means creating gaps between panels or the shadowing is going to offset any gains while also requiring far more panels and more land at which point you might as just angle the panels based on latitude.
actually this is "bad kind of article", because there is so much information in there / "everything covered". that it is almost impossible to have comments about it lol.
Literally laying them flat on minimally cleared land would win the simulation. Fewer panels, fewer acres, less mounting hardware, less labor, more power. Real world conditions not included in the analysis, such as wholesale electricity prices over a day and land not being flat, drives a lot of these choices.
Consider where that methane / natural gas is coming from. Their homepage says (with the world's most convoluted hyphen-omitting compound adjective, but basically see the last 6 words):
> March 2024: Terraform completes the end to end demo, successfully producing fossil carbon free pipeline grade natural gas from sunlight and air.
If you take carbon from the air, mix in energy from the sun to turn it into a fuel, then burn the fuel (undoing the reaction), where is the pollution?
There's more efficient ways to solve the climate problem than to install ginormous amounts of gas production, like you can run a heat pump instead of creating methane from that energy, but it's a solution that'll please even the old farts (no pun intended)
Not seeing the economics for this ever truly working out, CO2 PPM is very low despite our best efforts and the amount of energy required for separation is substantial.
We researched this thoroughly in the early 2000s and came to pretty much the same conclusion even back then.
For us the main problem was the reliability of the mover. If enough panels face the wrong direction for long enough it is worse than facing the sun in a good enough fixed position all the time.
Our angle was to use a simple motor that runs with constant speed and use a special patented gear (called VIAX) to turn that simple movement into a sun following motion. The bet was that a still simple mechanical gear would be more reliable than complicated electronics.
In the end none of our simulations made us confident any moving solution wouldn't eat the profits.
EDIT: For anyone interested, here is the patent. I think it is a really nice idea. https://patents.google.com/patent/EP0114240A1/en
This was going to be the gist of my reply.
I don't have the depth of experience with solar installations cited in your comment, but I have worked with systems that expected automated moving parts to continue to function in an outdoor environment. They all required near continuous maintenance.
Having a high level of cynicism regarding the utility industry, I wonder if the preference for moving parts is due to the requirement that only a large company with a constantly employed force of service personal can manage such a system. This would provide a certain amount of cost-of-entry that only large utilities could provide.
To quote what a utility company's compliance office once said to me, in a different context, "Only big companies can do that".
I saw some guy in Britain that replaced his old fence with one made of solar panels because the cost difference between that and traditional was nil.
I have a fence that gets absolutely blasted with High Grade Texas Sunlight. It shortens the fence’s effective life by years — this idea is brilliant. Now I just gotta price out 80 sq m of solar panels.
EDIT: The fence gets at least 4 hours of direct sun in the winter; up to 7 in the summer. I can easily install 10KW of panels. I don’t have any way to store the power. I suppose I could build a giant Tesla coil and zap the neighbor’s dog?
You can push excess power into the grid. It will reduce / reverse your electricity bill. Look into local regulations.
I've got a co-op that won't net meter below a fixed cost that's close to my monthly. I just like the idea.
A kWh of batteries costs about 200€ where I live, but if the panels cost a comparable amount to a normal fence you can probably just run the AC a bit cooler when the sun shines and use your house as a thermal battery.
Hold on, let me translate my stupid freedom units into Science™. My exterior house walls are already ... 30cm thick? That's 15cm of insulation + structure, a thermal gap, and then 10cm of stone facade. I only have to run the AC for a few hours at night, once the house warms up after a full day of sun. The only time of year I need "full AC" is during the high summer when the temps go above 40°C. What really kills me is that house is heated with propane, owned by a local monopoly, and the cost of propane has a 300% surcharge. The next time the HVAC packs up, I'm getting a heat pump, and adding solar panels (I only need a few); the savings in propane will pay for the HVAC/solar in a few years (in fucking TEXAS). The irony of this is not lost on me.
If you had a solar fence you could run the AC during max solar production for a couple of hours and not use it the rest of the day then. You might want to do the math on replacing the HVAC with a heat pump before it breaks, might be a good investment.
There's an enormous premium on heat pumps in the U.S. So, there's a manufacturer of heat pumps here, in Austin; they sell a heat pump for 1600$ in Australia (installed); but the same unit is 9000$ (installed) in Austin. Part of the difference is labor (about 1000$); the rest ... I dunno? The difference in cost in electricity vs. propane runs about 1500$/yr. My current HVAC unit is good for another 5 years, or so. I'll just wait it out.
1500 return on 9000 investment is 16%. Hard to beat that with other investments.
Can't you buy some home battery backups and either use them for time shifting (buy low, sell high) or just for backup power?
Our research around the same time came to the conclusion of a sun tracker, with wind protection, would be the best option. The panels were very expensive (a 400'ish W panel that today cost $80 costed around $2,500-$3,000), so aiming for the absolute best performance for the panels was key.
The trackers fail sometimes, but I would say once a year or so. The electronics are not that complicated, and its reliability was higher than the motor itself. I remember calculating with fixed tracking of the sun (because you know were it is at all time) vs photocells that tell the motors were to move and by how much. The trackers win because when the day is cloudy the best performance is to put the panel flat and let it rest there (instead of tracking a sun that isn't there so the motor that day consume more energy that the panels generate), and with enough cloudy days the tracker outperform the fixed tracking by a significant amount.
It's not until recently, with 400W panels under about $500, that tracking no longer makes sense, at least in our latitude.
I always thought that someone would invent a cheap, simple, reliable, and passive tracking system. No need for sensors or intelligent electronics.
You have a simple motor that slowly tilts the array from facing East to facing West as power is being generated. The motor does not start until the panel is generating a certain amount of power. The motor runs at a fixed rate with a screw that takes about 7 hours to move the panel.
Once power stops (when the sun sets) weights on the opposite side slowly tilt the panel back to the starting position so it is ready for the next day.
The motor itself is a moving part that is subject to wear and tear and reliability and parts availability problems. Solar manufacturers and retailers are notoriously short lived and fragile (in terms of being able to survive changing conditions, like Chinese subsidies, price dumping, and now tariffs, not to mention technological improvements in module efficiency).
If you buy a bunch of commodity modules (panels) without moving parts, you generally don't have to maintain anything except maybe replace the inverters in a couple decades. And you can do that with any electrically compatible parts.
If you have a moving motor, suddenly you need to find all the specific parts for that particular motor, and hire a specialist crew to maintain and replace it, requiring a team with not just electrical knowhow but motor mechanics too.
That's largely incompatible with the US model of solar deployment we have now, which is largely "install and forget" using whatever equipment is currently cheap and available. It's very likely that the equipment manufacturer won't be around in a few years, and that installation company probably won't be for much longer. So any additional possible failure mode should be avoided.
At commercial or utility scale it might be different, but generally it's still more cost effective over time to just buy more modules to offset the less than optimal facing than to try to actively adjust their direction with moving parts. Modules keep getting cheaper. Motors, and more importantly, shipping and labor don't. Installing an overcapacity upfront is still cheaper than maintaining the trackers later.
Good idea but has one major drawback: Shadows cast on single panels mid sequence would offset the angle. But majbe it is still worth it.
Like a big, very simple clock basically.
A big, not so simple clock moving a heavy array in all weather conditions, having to deal with constant changes in humidity, temperature, thermal stress, potential salinity, wear and tear, lubrication, gears, jams, etc.
A large reason solar is winning out over wind is because the lack of moving parts drastically simplifies installation and maintenance. A solar tracker isn't as complex or high up as a wind turbine, but it's still much more complex than a standard roof or ground mounted array that doesn't move.
Trackers made sense back in the 70s and 80s when solar PV tech was still new, but now it's far cheaper to just add more module capacity than to try to dynamically optimize each module's facing through the day.
I agree that it adds complexity, but it seems to me that the minimum there is on the order of the joints on a lawn chair, a screw drive, and a stepper. Not exactly high tech and if sufficiently overspec'd not likely to fail even in extremely adverse conditions.
The thing is that most solar projects are commodity energy projects optimized for cost per watt, not necessarily reliability or efficiency (watts per area). We're not building them for the constraints of Mars bases or fancy spacecraft, just run of the mill generation.
Thus the tracker has to not just pay for itself, but be a better investment than simply buying more modules. The goal isn't reliability at any price, but cost effectiveness compared to making the project a little bigger and adding a few more modules.
Even with home rooftops (which have limited space), it's much cheaper to buy more premium modules with higher efficiency, or optimize their outputs with per module micro inverters or optimizers, than to mount the array on a tracker. With big commercial installations, there's even less of a space premium.
Trackers aren't just a one time upfront cost of manufacturing either, but an ongoing maintenance cost over the lifetime of the project. They get more expensive as less and less of the industry uses them and fewer parts and labor are available for them. They just can't compete with the Chinese dumping of cheap modules, which are so cheap now that almost all non Chinese manufacturers have gone bankrupt. So the industry is left with a glut of modules, which are probably just going to get cheaper and more efficient, while tracking technology and costs haven't improved anywhere near the same amount. It's all relative, and the trackers are losing big time.
Sure, as a science project with infinite funding, maybe you can make a super reliable one. In the real world, though, installations across the world have found them largely unappealing from a cost effectiveness standpoint.
I just spent 6 years living off-grid, running 5kw of solar, and 14kWh of storage. I setup a fixed array that I welded together myself. I could certainly see that tracking wasn't worth it even then.
However, in the off grid-setting I did discover some nuance. Sometimes you could really do with some power around sunset or sunrise. In the winter, being able to more reliably run my air-source heat pump at sun-up would have been very handy. Or likewise, some extra power to run the AC (which is the same device) in the early evening in the summer would have also been handy.
There were plenty of cold mornings when I was keeping an eye on the solar grafana dashboard, waiting for that hockey-stick moment when the sun swung into the right place!
I did consider the possibility of setting up an additional east or wast facing array to capture sun at the extremes of the day. Unfortunately that would have required its own MPTT charge controller, and would have just been more complexity in general.
Tom Murphy shows in his excellent book on energy that over-tilting your solar panels by 15 degrees is a good idea (Table 13.2):
https://escholarship.org/uc/item/9js5291m#section.13.4
Basically take your latitude and add 15 degrees and that'll get you good annual coverage.
Wouldn't it more reliable, day to day, to oversize the production during the sunniest parts of the day and then dump that into storage to use whenever you wanted, not only during twilight but whenever it was cloudy, freak weather conditions, etc.?
Some of that you can solve with dual side vertical panels mixed in. Obviously murders their output but you get it when it matters - on the shoulders of the day
I honestly don't think I would be comfortable off grid without 4x+ that size. Of course, environments vary so significantly that these numbers don't translate well when discussing them without geographic context.
My primary concerns would be consecutive cloudy days, and winters with very short days. While my actual heating/cooling needs are more mild than global averages, I think the combination of short daylight hours and increased heating needs makes off-grid solar unviable for climates closer to the poles, especially those not near sea level. I do think relaying on propane or wood for heating might make off grid viable for these locations, but that introduces questions of scalability and increased carbon footprint.
There is some argument that burning wood should be considered carbon neutral if the trees are replanted and used as a renewable resource (Carbon is released to the air, and then captured by the next tree in a cycle), but the land intensive approach wouldn't scale to meet the heating needs of a significant portion of the population. Additionally it ignores the carbon required to grow, harvest, process, and transport the trees or the alternative uses the wood might find elsewhere.
My point is for others to take their local climate into consideration before thinking that 5kw/14kWh would be enough for them to go off grid.
I think it entirely depends if you want a 'just works' solution or you're willing to adjust your lifestyle day by day based on availability of sunlight.
Merely a 10 watt panel in the Netherlands has been fine whilst camping for weeks, but obviously I have to severely compromise on modern life - 10 watts powers a lamp for a few hours in the evening and a phone charge each day.
In these sorts of rare situations it is of course possible to run a generator to charge everything up. Off-grid doesn’t mean on an island.
The insane energy density of fossil fuels means this is an excellent “emergency” back-up plan should the sun not shine often enough.
I'm not sure it's rare to live about 45°N, where we start to see >9 hours of sunlight in the winter. The intersection of places that are both above 45°N and very cloudy (Portland, Seattle, London, Detroit, Copenhagen, Dublin, Vancouver) or in high altitude probably includes a good chunk of HN readers. Northern Europe gets down to about 6 hours of daylight in the winter. If you're in one of these regions, and you plan to use a generator to augment your energy needs, I don't think that's considered an emergency as much as a secondary power source. If one of your goals is decreasing carbon emissions then a diesel generator is going to set that back.
Other regions will have their own considerations, but the primary concern is balancing harvesting sunlight with heating/cooling requirements. I'm just encouraging people to do their own homework for their own situation when considering off grid. I've seen a lot of people under build and end up spending way too much to heat their homes in winter.
What is the appeal of living off-grid?
Sometimes the appeal is not in the "off-grid" itself, but in living in a remote location where having access to the grid is impossible or inconvenient (it does not have to be too remote either to not have easy access to the grid).
This is what I observe as a Realtor and living in a somewhat rural area - there are some people who like the idea of living the self-sufficient lifestyle, there are others who are convinced Armageddon is upon us and they are going to be ready, but mostly its because they found a beautiful location that speaks to their soul and the only way they can make it work is to use off-grid resources.
You don’t have to be around other people, and all the hassles that human society and population density entail.
Some people are really into that. I’m really into same-day Amazon delivery and 30 minute latency on fresh pizza that I didn’t have to cook.
I just wanted to say thank you for the phrase “30 minute latency on fresh pizza”
I’d never considered it latency but you’re right and it’s hilarious.
Taking time to cook elaborate meals is enjoyable if it isn't getting in the way of some other demand on your time. Living off grid you're probably going to have a lot less of those.
Living off grid means off the electrical and water/sewer/gas utility grid.
In almost no case does it mean off the internet now given Starlink; thus I think it’s silly to assume that a) being connected to the internet and b) having to admin all of your own utilities and associated equipment means you’re going to have fewer demands on your time. :D
Separately I love cooking as recreation, but don’t have much recreation time these days given my project-load (most of my projects being a form of recreation notwithstanding).
One of the reasons I am building a (mostly) off-grid place is because I like adminning infrastructure recreationally. I can’t wait to hook up my solar system to Home Assistant and Prometheus/Grafana.
I've been in solar energy as my primary vocation since the 1990's.
I've built solar cars, I've built solar panels, I've installed solar panels, I've designed solar trackers. I know this industry inside and out.
I'd never heard of an east-west array before (though I did experiment with one-cell-wide "crinolations" at 60 degree angles, did not find any value to using them but it was a different application where low-angle light wasn't a factor). I'd never thought of such an array on this scale, at this low angle, before.
I don't think most of the people reading this article quite understand that this is a completely different kind of array topology to flat-plate fixed-tilt, or tracking-based systems. Do yourself a favor, if you consider yourself intellectually curious, and if you came away from skimming this article thinking there's nothing new under the sun, read it again with a keener eye toward the novelty of it.
I have an east/west array on my roof, as my house is positioned with the front facing west.
In the winter it's outperformed by a south facing array (northern hemisphere) but in the summer the east array gets a ton of sun before midday, and crucially, it's getting a ton of sun when the temperatures are a bit cooler, so it performs very well.
I actually use this exact example when encouraging careful attention to paradigms where a fundamental variable is slowly but consistently changing.
It's essentially equivalent to a boundary on a phase diagram: Cost/Watt has fallen past a critical threshold, and suddenly this dramatically different approach just makes more sense.
Another interesting configuration is vertical bifacial panels aligned on North-South axis and interspersed with farming rows. Low-cost panels make it feasible and it doesn't much block agricultural production if the panel rows are spaced far enough apart.
I guess trackers really are an American thing? I’m in solar for ten years in The Netherlands, and I don’t think any utility scale fields use tracking. For residential roofs east-west placed systems have been an option for the same amount of time. They are now gaining popularity in The Netherlands because of net congestion during midday.
Trackers are useless when the majority of the incoming sunlight is diffuse (as is the case where you live).
Trackers are useful when the majority of the incoming sunlight is direct (America has a mix but the western half and parts of the south have a lot of direct).
Trackers are essential when you use concentrated sunlight.
A tracker that doubles the amount of sunlight hitting a panel is not free, but it also makes the panel take up 2x the area, or more, to avoid shading its neighbor.
The thing people tend to forget about trackers is they offer this trade-off where you can trade shaded area for power per rated panel. When land is cheap and panels (or arrays, heliostats, power towers, etc.) are expensive, trackers make sense.
The reverse has been the case for the past ten years, and continues to get more true by the day. I doubt we will ever see the day return where land is cheap again and/or PV are expensive again.
Thank you, I went back and re-read after seeing you comment and I did indeed miss the big point here. I had been concerned that even if PV costs reach near zero, the fixed install costs would still limit future reductions on solar costs. Clearly not!
Looking at the graphs, the tracking arrays may have the added benefit of generating power in the mornings and evenings. If everyone builds non-tracking arrays, power during peak will become almost worthless if solar is a big part of overall generation capacity, so the economics might change even with panels being cheap.
Of course, just building 2x as many permanently tilted panels might also work.
Edit: the article actually addresses this: "[fixed setups] can pack 250% more installed power into the same space when compared to a single-axis array" - so even if only the power in the morning/evening has value, there is little reason to install tracking ones.
This is one of the areas where double sided panels reportedly win out. You can orient them to morning/evening light and they shed heat by convection better. Hot cells produce less electricity, which is why it’s difficult to construct Maxwell’s Demon from eg infrared-sensitized photovoltaics and band gapped radiators.
> If everyone builds non-tracking arrays, power during peak will become almost worthless if solar is a big part of overall generation capacity
During peak solar yesterday in California wholesale power was $5-6/MWh (<1c/kWh).
The CA grid is routinely over 100% renewables during springtime. The excess is handled by having a lot of batteries, exporting energy, and curtailments.
Yeah - you can’t talk about renewable energy generation without also considering when it is generated.
Then future price of energy will be incredibly time dependent. Finding a way to generate at a different time than everyone else - whether by east/west panels or time shifting with batteries or building a different kind of renewable generation is where all the big profits will be.
Demand isn't fixed in time either, though. Industrial processes that presently run at night to use cheap power will switch to daytime when it makes sense to do so. Summer mid-day also has the highest electricity demand all year in many places due to air conditioning, so arguably solar is addressing one of the biggest stress points.
Not an expert, but my understanding is that the challenge there is that a big cost in industrial production is the initial capital outlay for the equipment, and oftentimes to pay that back reasonably, you need to run the equipment nonstop. Also, some processes are challenging to stop/start.
This has been my understanding as well. But on the plus side, while you may run a machine all day, the price of cooling your equipment varies with the outside temperature and that is highly correlated with available renewable power. The AC units and diesel backup power are systems you buy and prefer to have idle. But not your press or data center.
"summer mid-day also has the highest electricity demand all year in many places due to air conditioning,"
Peak electric demand is 3-7pm in the summer. You might think you could then just set panels to to optimize for afternoon, but especially in winter, you get a big peak between 6-9am.
What if you manually adjust them based on the season?
In the West, the cost of labor makes that unappealing. From a DIY standpoint it'd still be a pain. Those things are heavy and usually require at least 2 to 4 people to install or move. It's not something you'd want to do regularly if avoidable.
I see.
I imagined then being panels on like a hinge that you like unbolt, tilt a little and then bolt down again. I didn't know it would take multiple people to do it.
Yeah, you could maybe design something like that. It'd still be quite a lot of work to go through all the panels one at a time every few months, though. And doing the math to remember what angle to point them at would be annoying and error prone.
Totally depends on the location. Say, Northern Europe has traditionally very little AC (changing thanks to dual use heat pumps) and the energy use naturally peaks at the depths of the winter.
It already is on wholesale markets - in the UK you can get on Agile Octopus which gives you half hourly prices. When there is a glut of renewables on the grid you can end up being paid to use energy.
This highlights the need for grid scale storage (be it batteries, pumped hydro or something else) to balance Solar PV, and to bridge gaps when the wind isn't blowing.
Power during those lull periods will get expensive, and that’s likely to result in some farms with permanently tilted panels that prioritize those periods over peak overall production.
Space is cheaper than maintenance and breakdowns in many cases.
but, 70% of MY! yearly households electricity consumption is literally into [PV!] hot water. Hot water tank is cheapest energy storage device on planet. and i do not have to worry to shower in noon, i can just charge my water tank during day, even when im not home. and use hot water in evening. for very little price - no need to use heat pump, resistive heater is super cheap. hot water tank can be made even DIY to lower price even more.
utility charges me so much for electricity that even tho i payed for 15 kWp roof mounted east west system literally literally ORDER OF MAGNITUDE more than prices showed in that article, AND i still save money by not buying electricity from grid !
that how much utilities are charging us, yes they need to manage all those wires, manage power plants, etc. i do understand where that cost comes from, but still, solar in residential is so cheap that installing PV on roof and directly consuming it will save you money.
So for industry/ manufacturing there will be extremely high incentive to add PV + battery even when it wont cover 100% of their loads. utility+ onsite PV+battery.
Again, back to my hot water system, 80% of year i am 100% "off-grid" for hot water [PV!]. even on days it is cloudy ! And 99%-0% of PV rest of year... And from april to October my electricity draw from grid is almost zero.
so whole residential USA can be essentially "off-grid" huge part of year with just small battery, your tv, notebooks draw almost nothing over the course of the day compared to your energy need for hot water. and less residential is on grid, easier it is to manage electricity for other sectors of economy.
this contraption from ETH Zurich can store iron/iron oxide to generate hydrogen, without storage loss! for years, without compressing hydrogen and without other cons of "standard hydrogen storage. essentially it can be thought about as hydrogen storage - it can "store" 10s of megawatts inside of a standard basement. - [https://ethz.ch/en/news-and-events/eth-news/news/2024/08/iro...]
and you do not need to make electricity from that hydrogen, you can heat your house directly with hydrogen, just by replacing 30$ burner in your existing furnace!
so you complain about "peak" power excess, and i say and i show it to you that this "peak" solar power can be used to charge that extremely cheap storage device in summer and expend that storage over winter for heating house and making hot water. when sun is not shining.
and again, calculate how much kWh is your need for heating and how much is for hot water and you can clearly see that extremely huge part of current residential energy need can be either "onsite off-grid" with this contraption + small LiFePO battery or to be on-grid and take only small loads like tv, notebooks from grid and having heating + hot water "onsite off-grid". and most importantly cheap.
ratio of kWh for your heat and for your other appliances ! ! ! !
So essentially we can charge our heating system in summer, store energy WITHOUT LOSS until winter and heat with that energy in winter. right now!
just sketch/draw for yourself timeline containing - PV + storage contraption in that link + small LiFePO battery. and you can see how huge part of energy we do not really need to draw from "grid".
small towns can even make their own shared storage, prices for SEASONAL energy storage are even lower then current prices for electricity drawn from grid....
So this physical, economical actual contemporary possibility makes me mad every time i see just another youtuber or other kind of influencer, post about just another battery technology promising who knows what, in who knows what timeframe.
we do have energy storage technologies capable of providing citizens of USA with clean energy RIGHT now, RIGHT here. for whole year, day and night. without buying one drop of oil from tyrants, dictators who literally literally kill people right at this moment.
[https://apnews.com/article/russia-ukraine-war-drones-kharkiv...]
this world is so frustrating ! XD
I didn't read your entire comment (sorry), but wanted to support your water tank statement.
I live in an area with frequent, often day long power failures during winter storms. So my house is designed around that.
When I bought a new hot water tank, I spent a little extra for the super insulated one. The result?
I can take a shower during a power failure, and still another not as hot 24 hrs later! When you consider that the first shower injected cold water into the tank, that's fairly impressive.
On long power failures, on the third morning I can even take a lukewarm shower, with no cold water at the shower (I have individual hot/cold controls). This is far preferable to a shower at 5C water temp (from my well in winter)
And where did any eacaped heat go? Why... into my house! Surely not a loss.
So yes, water tanks rock.
Yeah, similarly with insulation / good building practices, my house can lose power in coldest of days and i do not have to put on hoodie for 2 days. (not heating by other means like wood, which i do not have) it is not big house tho. it is insane to me that in country where there are tornadoes, hurricanes, wildfires hundreds of times per year, we do not do this / build like this by default.
In europe, there is possibility to be on "energy spot prices", essentially utility will charge you energy market prices. today price at noon was almost zero. last Sunday, prices were negative - they literally pay you to draw from grid. but at evening, price can be quite high.
so having simple time relay / or more complex minicomputer directly reading energy market prices and switching loads can even earn you some money. it is not money making business but overall price can drop significantly. it is also an economic incentive to buy battery storage and actually got to paid it off.
Enabling citizens to do good thing is underrated.
people with "standard" contract are essentially subsidizing industry, corporations which have cheaper electricity because of bundling with residential customers. which makes weird and complicated incentive structures. essentially anti-market behavior in country which boasts itself in "capitalistic" structures... and slowing adoption of renewables, because it looks like they are more expensive than they actually are.
I read, and appreciated, your entire comment - thank you.
You describe a simple and elegant solution to some portions of these problems and what you are doing with your hot water "battery" is smart.
I am forced, however, to ask:
Where do you live and how large is your family ?
My suspicion is that you do not live in the United States and your family is relatively small ... ?
Modern, "first world" ("global north" ?) 21st century homes do not match your model in a number of different ways:
- Unlimited, temp stable hot water comes from a tankless water heater. People don't "run out" of hot water anymore.
- A family - even a relatively small family - runs a 30A dryer daily. Our family of five runs it 1-2x daily.
- Many, many people now have electric cars and some households have two of them.
- I agree that laptops and phones and personal electronics are a rounding error here but microwave ovens, toasters, coffee percolators, etc., are not - and people use them. I will note in passing that both our dishwasher and our microwave oven require 20A circuits.
I am optimistic that we (as a society) can satisfy these demands with solar power - I just want to make sure you appreciate just how much demand for electricity a modern US household has.
FWIW, we are planning on going entirely off-grid, purely solar with lifepo batteries, in the next 18-24 months.
Americans basically live like energy is unlimited, free and has no side effects, the rest of the world doesn't have that chance, last time I checked the average US household used anywhere between 3x and 4x more electricity than the average EU household
They tend to prefer huge houses with relatively complex designs (less optimal in term of area/volume ratio) / poor insulation, they make up for it by relying on tech for heating/cooling pretty much year round.
Your tankless water heater is a good example of something that is completely inadequate for solar setups, they draw insane amount of energy over very quick period of time. But I think that's the core of the issue, if you want to keep all the nice things modern American houses have you're going to need a lot of money and a lot of sun. On the other hand if you're a bit more frugal, with so called "passive house", you can get by with a much smaller setup.
> I will note in passing that both our dishwasher and our microwave oven require 20A circuits
And a tankless heater will need 5 times that, unless you're using gas but I wouldn't count that in a "modern first world 21st century home".
"Americans basically live like energy is unlimited, free and has no side effects ..."
Agreed - and guilty as charged which is why we're switching entirely to solar.
(I will also note that my household "cheats" by living in California where we need relatively little heat and do not even own an air conditioner so our path is, perhaps, a bit easier)
My main point is that whether you're a frugal EU council house or a profligate Texas McMansion, we - all of us - will continue to invent new demands for energy and continue to trend towards more energy used per person per unit time.
Therefore, if you're looking ahead to deployment of solar resources you should be realistic about that trendline.
> we - all of us - will continue to invent new demands for energy and continue to trend towards more energy used per person per unit time.
I'm personally in the process of designing my house and I'm going for maximal energy efficiency: 38cm thick brick walls + 20cm thick rock wool insulation, basic rectangular shape, 80% of the windows to the south, triple pane, heat recovery unit coupled with a air/earth heat exchanger to avoid needing a resistance to pre warm the air in winter, heat pump water heater, catalytic wood stove
Although I would agree that overall people don't give a shit and I probably am in the minority
It's good that your daily "30A dryer" usage will soon be solar powered. I have a solar-powered clothes dryer too — it's called a clothesline.
I appreciate frugality, but a clothesline takes significantly longer to load and unload. It’s not an ideal replacement.
> Your tankless water heater is a good example of something that is completely inadequate for solar setups, they draw insane amount of energy over very quick period
I know nothing about any of this, so please educate me for the good of us all - wouldn't this logically be a use case for a battery? IE: solar (or wind or whatever...) feeds a battery that feeds the tankless water heater. As a layperson, it would seem to me like the issue isn't generation but rather availability at the moment of demand - which would be the case in any kind of micro generation, right?
"Ordinary European household" will change even lower :
Crisis of 2008 made EU to think about resiliency so they asked all kinds of economists, physicist, other science people what should be done to provided that and one of those things implemented was building energy efficiency directive [https://energy.ec.europa.eu/topics/energy-efficiency/energy-...]
which progressively increased demands on building sector to provide citizens with "low energy" housing. and currently most states of EU have requirement to build houses where defacto energy need for yearly heating of a house is lower then energy yearly demand for hot water (hot ater can not be lowered significantly without heat pumps - COP3+)
You should still probably add a hot water tank to that setup, just put it in front of the tankless heater. It is a like a battery that is 100x cheaper. You could go high tech and run the tank heater when you have solar excess, or low tech and just put it on a timer to run for a few hours around noon.
Everyone should calculate how much is consuming in kWh, recalculate gas into kWh, wood into kWh, propane into kWh.... then it starts making sense for ordinary people. Even for how much energy leaves their house. To use kW / kWh for everything.
" 1)- tankless"
more than half of USA has water tanks. both water tanks and tankless heaters have expected working life, after taht they have to be replaced either way.
Tankless heaters are more efficient if you think only about AMOUNT of energy, but water tanks are there to lower your PRICE of hot water. (or spread load over longer time for usecase as your offgrid) So yes, with tankless you are doing best in standard "old" grid situation, where price for electricity for customer was same throughout day, (some tariffs can have different price in night) (or when you ask Ask This Old House)
AND with PV! on roof and tank in basement, households are providing service for utility because A) they do not export solar at noon, they are putting that energy to water tank, B) they do not import energy during evening peak hours. so less generation / "base load" needed to exist, to operate, service, manufacture.
but there are new things like solar export which will change grid. and people have to adjust, or they can just install expensive battery paid with gov subsidies (by "utility")... residential customer can either use cheap electricity during day to heat water tank or utility can charge for "stabilising" of grid multiples of that price.
so customers incentive should be to have hot water from PV on his own roof. and when they do not have enough solar energy they can charge rest from grid. and lowering need for importing from grid by 80+% per year... for hot water energy.
"2)dryer "
how much is that kWh ? can it run during day when there is availability of PV ? Or atleast one of those cycles can run during day?
" 3) electric car "
I am one of them but unfortunately i am working from home and have nonstandard schedule (20-45 miles per day + once per week trip to buy groceries in town 130 miles ) so i can charge my car from PV, not many people can do that. but they can have water tank on PV and car on grid... or if they use one car only sporadically, then that one can maybe charge from PV ?
my electric car can be charged by 2kW from standard outlet for 10 hours to add 62 miles of range, in summer when i do not want huge loads or i can connect it to faster charger. one car takes daily roughly same amount of energy as 2 people need for hot water...
"4) appliances "
how much is that kWh ? starting current can be higher, sustain power can be lower. starting power can be lowered by using "starter circuit" - bunch of capacitors connected to motor, but lot of motor apliances already have it. coffee percolator is essentially water tank so you are already doing it ;) 20A is not much, some appliances can be connected to 240v if it is available. or adding more circuit breakers if you have slot for them, and spread loads between circuits.
"5) rest" not waste, save, use on site first, then grid. most people live grid first... i do not mind grid
im not saying everyone should go off-grid, because high-rises can not. but everyone who can, should atleast be able to have 5-10 kWp PV on roof just for hot water, and it can be used in emergency for other things (not necessarily same lifestyle). such small pv + hot water tank as a predictable load connected to well sized PV can make PV be payed sooner. and having connection to grid, with possibility of getting payed for export of excess in future for powering highrises...
my system got payed in 6 years because i use a lot of energy directly. lifetime of inverter is presumably 10 years and panels 20 years so i have presumably next 4 years energy for free. then i have to replace inverter,... if those devices last longer, saving is even bigger.
50 degrees of latitude, north temperate zone, temperate climate,
I wonder if you could make a DMD [1] where instead of mirrors the tilting part is tiny solar panels?
The panels would only have two positions, but you could install half the DMD devices so that the two positions are south and southeast, and half so they are south and southwest. You could then have half your panels southeast and half south in the morning, all of them south midday, and have southwest and half south afternoon.
That would get you at least some tracking and it should be mechanically a lot more reliable than the systems that move large panels.
DMDs were designed for use in video projects, where they have to move the mirrors more times in 4 hours of video than a solar array would need to move the panels in 1000 years.
[1] https://en.wikipedia.org/wiki/Digital_micromirror_device
Too much complexity and maintenance. Solar panels are dirt cheap, and with fixed mounts, zero maintenance. The rack you mount them on costs more than the panels.
The only reason I can see for added complexity is if you're space constrained, and in almost all cases, not cost efficient.
A DMD is a really good thought, but I don't know if the surface area would work out at scale.
I think the power handling limit of typical devices is something like 100W/cm^2.
The UV from the sun would also degrade these devices faster.
We have an east/west roof with solar on it. It is less efficient than our previous roof which was pure south - but it smooths out the generation and gives us more electricity in the evening.
I have some pretty graphs at https://shkspr.mobi/blog/2020/04/comparing-solar-panel-gener...
When panels are cheap what about vertical mounting? Less susceptible to hail and snow. And maybe placed north-south, to maximize production in morning and evening when it's needed most.
The article seems to be mostly about grid scale solar. Of course an increasing amount is private or domestic solar installed on e.g. building roofs or wherever there is space.
When cost drops low enough, any surface with any exposure to sunlight is in scope for installing solar on if it can yield more energy than the cost of installing solar on it. It stops being about what is the most efficient and starts being about if the surface is good enough to provide a decent return on investment. Maximizing that ROI is complex but it boils down to getting more value out of the installation than goes in.
Solar doesn't even have to be in panel form. Some office buildings now have windows that double for solar generation. A thin transparent coating does the job. There are roof tiles that double as solar panels. Aptera makes electric cars with integrated solar panels. These are curved glass panels that are manufactured to fit the profile of the roof and hood. It's also possible to print organic solar cells directly on plastic rolls. No glass involved. Or panels. Those are less efficient but you can integrate them on all sorts of surfaces. A lot of that stuff is still emerging technology. But especially organic solar printed on plastic rolls could end up being very cheap to produce. And very light.
Domestic solar is a rapidly decreasing fraction of total solar deployments [1]. Not because it is not growing exponentially, but because grid-scale is much more exponential with no signs of that changing.
[1] https://news.ycombinator.com/item?id=42591918
“When cost drops low enough, any surface with any exposure to sunlight is in scope for installing solar on if it can yield more energy than the cost of installing solar on it.”
I don’t see the logic? As panel prices drop, installation costs start dominating overall cost of energy produced and so economic pressures will be on simpler and simpler PV installations. Laying a panel almost flat on the ground amongst thousands of others will be a cheaper process - both initially and in terms of ongoing maintenance - than anything that involves sending workers up ladders or cherrypickers attaching and wiring a panel onto the side of a building.
So grid scale will start to dominate over domestic or “novelty” (e.g. floating panels on reservoirs) and simpler and simpler approaches to installation (like removing tracking) will become attractive.
These effects are already apparent. Basically the opposite of what you’re predicting?
> I don’t see the logic?
You use the surface area you have. Most people simply don't have a lot of ground to put solar on but they might have a roof. Also, you don't just need solar panels but also the wires to where the power is needed. On the roof of the building where you are using the power is just about as close as you can get with that.
Otherwise it's a simple economic equation. If installing solar saves enough money such that you end up with a decent return on investment then making that investment is more optimal than not making that investment.
That's why most of Australia is running on rooftop solar when the sun is shining. The US is a bit behind on that mostly because the US has a lot of rules stacked in favor of grid providers. Australia used to have that and eventually the grid providers lost that battle.
Installation costs dominate largely due to one-off things (getting the contractor/customer, roof access, adapting to bespoke roof layout, etc) which are disproportionately larger for smaller installation sizes. However for new construction those things are essentially free. So yes, I’d absolutely expect that solar will be added during larger rebuilds. But that is not an effective way of “deploying solar”
Grid scale solar benefits from bifacial cells in a vertical orientation just as much as home scale solar - it dramatically improves winter production and extends the production of the spring/fall day a few hours earlier and a few hours later.
Not only does it increase overall production, currently one of our biggest challenanges is transport and distribution, and having some of that power in the of-hours instead has more benefits than power total alone.
you also appear to get efficiency gains as vertical panels don’t get as hot - https://www.pv-magazine.com/2023/11/10/researchers-shed-ligh...
I’ve seen some YouTube videos of people making solar fences with bi-facial panels. If I recall correctly on the one I was watching, they were going for morning and evening production and faced them east/west. One side would get the morning light then the other the evening light.
(not sarcasm)
Yes ! Triple price of PV panels to buy "ceramic glass print" PV panel with eye pleasing pattern / stealthy photo on it and you can have facade or fence made from PV panels, there is drop in generated power from 10-50 % depended on pattern, color used.
Price per panel not price per install ! ! ! And subtract need to buy materials used for that purpose before.
Balcony Solar is a thing, most of the panels will be vertical in that use case.
Yep, but you're severely limited in terrain types. Unless you need the "fence" cover, I can't see it being worth it due the efficiency loss.
It’s mentioned in the article that sunlight from near the horizon passes through a lot more atmosphere, which attenuates the light so much that you might as well not bother with the panels.
That depends on your latitude, how dear land is, and how close to breakeven your application is.
For a lot of applications, panels are so goddamn cheap now and breakeven happens so fast that "Just buy twice as many panels" is the best solution to any problem that doesn't involve land area. Winter production in a snowy/leafy climate at a latitude tilt, though, is the exception to the rule; Production is so impaired without regular maintenance that twice as many panels is not very helpful. But set those panels vertical, at a range of orientations, and snow/leaves stop being an issue, you get sizable exposure with the sun low on the horizon, the maintenance requirement goes away, and you get an appreciable amount of power earlier in the morning and later in the afternoon, you just don't get quite as much at noon.
North South is exactly opposite of what you need, the sun is never north
I'm pretty sure by north-south they are talking about the direction the panel lies in, i.e. the faces point east/west.
But even under your interpretation, you aren't always right. If you're far-ish north of the equator you want south facing panels (and the reverse) and if the cells are cheap enough it makes sense for those panels to be bifacial, with one side permanently facing away from the sun, to get a bit of extra energy from ambient light. Especially in winter when there is less sun (so energy is at a premium), and highly reflective snow resulting in a lot of ambient light.
what if you're in the southern hemisphere?
Then, you’re a statistical outlier that can be ignored in the analysis :-)
(Only about 12% of all humans live in the southern hemisphere)
Then North South is still the opposite of what you need.
Genuinely didn't even consider this XD
I’m pretty sure they mean that the width of the panel is north-south so faces are due east or west
Trackers tend to suffer from mechanical failures. Even 15 years ago, there was only one way to make money out of solar panels: Install them and forget them. If you need to waste time and money on the installation then the small profit vanishes really quickly. I really don't know how those companies convienced the investors for trackers.
I really like that how it's possible to put bifacial panels vertically along north-south direction to get solar power off peak. It should reduce cost of installation (it's basically multiple rows of fences), snow removal and cleaning. Washing down panels from dust could probably be automated too and if you build them up a bit higher you could have a meadow underneath or even a field of something. Hail should also be probably less of a concern. You need more land of course but it's still awesome.
Nature has come up with moving limbs on animals, but none of the trees seem to be tracking the sun. Branches are in fixed positions.
There are some plants that track the sun, e.g. https://youtu.be/w-adcjH-xyk?si=Pcx4ucVe1oVwbdH4
It's definitely the exception rather than the rule though.
Many trees don't but lots of smaller plants do tilt their leaves towards then sun and can be seen easily in a timelapse. And also like the other guy posted, sunflowers famously follow the sun.
Spamming leaves is probably just the cheapest strategy?
I used to work on solar power plants and solar tracking technology back in the late 2000s. Even back then, I remember frequently discussing that "eventually panels will be cheap enough that we'll just wallpaper the world...". It's really nice to see that coming true.
I thought this might be an article about a solar updraft tower, which also doesn't track the sun, or require solar panels.
I wonder if you could make deployment / installation even cheaper by making big “rolls” of panels and unfolding them directly on the ground. No ground pillars of any kind.
If you built a zigzag pattern into the panel, possibly with some ultra-cheap alternating cylindrical ground support, you could easily deploy them in this East-West configuration.
You will have to drive some pillars into the ground to secure them anyway, but it might be much faster and require little labor.
"Sunlight at angles below 15 degrees is considered nearly uncapturable due to the effects of the ozone layer scattering sunlight."
Surely it is Rayleigh scattering that is important, not scattering off ozone?
The graphs show huge price drops over the last ten years. I wonder, how different does the price look for residential solar panel installations? Presumably the labor will start to dominate the cost if it doesn't already?
Labor does dominate. Panels are dirt cheap and inverters, while they haven't come down in price that much, seem to still cost less than half of the price of the panels per watt.
One cool observation of an grid wide advantage is that single axis really normalize the power curve per panel. There are many reasons way more consistent production would be better.
I am curious if just having more fixed panels normalize production at scale
I'm probably not thinking this through, so go easy, but why wouldn't tracked panels also produce a normalized power curve? My assumption behind the question is that they follow the same track as Sol every day, which doesn't vary at least year-to-year.
No i am viewing from there graphs of power over the day not over the year.
Untracked panel production has a sharp peak at noon and that rises and falls pretty sharply before and after that. Maxing/stable between 10am - 2pm
Single Axis flattened that curve up very heavily so you were producing at or close peak production for much longer. 8am - 4 pm
The double axis seemed to just get slightly high magintude in power compared to the single axis which is good but definitely marginal.
The question would be is if you have an array of fixed panels can you fixed them in a way that flattens out the peak production but provides a more level and less peeking production for the grid as a whole. This is really important because its much harder to turn off/disconnect solar than other forms of power. The grid has to be sure it doesn't overcharge or undercharge the grid. If you do either you'll deviate from the target 60Hz (US) you can damage a switching and transformer infrastructure.
A less peeky supply is more predictable generally speaking and gives you more time to react to changes in the grid. The per cost question would benefit from answer this because it might make sense to install more panels in a fixed position that is not maximally optimal at an individual level but is maximal for the overall grid health. That investiment in deployment is worth it to make now because you'll never want to change it afterwards.
I always see articles about the decreasing cost of solar, but where are these costs collected from? Is it just not available at a consumer level? Maybe I missed the sources in the article somewhat...
There are lots of consumer facing companies selling panels. You'll need to buy in bulk (generally a pallet), but you can easily get them for $0.30 / watt.
Compelling analysis. But if hail damage is the primary concern, tracking seems like an X/Y solution. What about eg anti hail netting that can be rolled out when the weather forecast predicts hail? It seems to me like a middle ground might be automated deployment of hail protection, which by definition has lower aero loading than what amounts to a big semiconductor sail.
anti-hail netting? you must not be from somewhere that receives a lot of hail. hail punches through solid coverings at the right size. if it's not the right size, then it's not that damaging.
netting? ha! thanks for the funny visual so early in the morning.
Hail punches through solid coverings because they are rigid. They nearly instantaneously stop the hail which means they absorb all of the kinetic energy of the hail very quickly. They don't have a good way to dissipate that energy as rapidly and it goes into breaking the structure of the covering.
Nets are flexible. The energy of the collision goes into accelerating the net at the point of the collision. The net can quickly spread that energy into accelerating the surrounding areas of the net and so on. Unlike with a rigid cover this is not nearly instantaneous, so you don't have all the kinetic energy of the hail being poured into the net at once. That and the ability of the net to rapidly spread energy means that you don't get enough energy anywhere to break the net. It just stretches as it decelerates the hail.
You can see how this works by watching a soccer game and observing how the nets at the goals stop balls. Hailstones that weigh more than a soccer ball are extremely rare, as are hailstones that are falling faster than many strikes and penalty kicks in a professional soccer game, and you don't see many soccer balls breaking through the net.
People have calculated how fast a soccer ball would have to go to get through the net and found that it is over 220 mph. The largest recorded hailstone is estimated to have had a terminal velocity of 168 mph, based on size, mass, and atmospheric conditions. That hailstone had about 16% more kinetic energy than a 220 mph soccer ball and so might have broke the net, but soccer nets are by no means the strongest nets that can made. And remember that was the largest hailstone ever recorded--we are talking a once in decades event.
I think a hail net would be feasible for some cases. Golf balls break solid coverings too (and windows, car roofs, etc), but we have nets for them.
You want high tensile strength and some level of flexibility/elasticity to absorb the hailstone energy over a greater-than-zero distance. Or to shatter the hailstone well above the solar panel.
Probably too light-blocking to leave up continuously, and maybe awkward and failure-prone to deploy automatically.
So insurance is probably more cost-effective for most installations.
I agree with your implicit point that the key question is probably cost effectiveness compared with insurance. However, in the context of the OP, insurance premiums in hail-prone regions was listed as a prime reason why single-axis-tracking panel installations are, in some regions, probably still a better bet at grid scale.
The point I'm trying to make is just that there are a lot of off-the-shelf (or nearly so) hail protection strategies that seem like they might have better economics than single-axis-tracking installations, which might improve the cost effectiveness of a fixed panel installation to the point where, even in hail-prone regions, it might be doable.
To be clear: anti-hail nets are already a COTS product, just not for this application (as far as I'm aware). Nets are just really, really good at absorbing kinetic energy. I mean, that's effectively what kevlar ("bulletproof") vests are made of -- netting with a very small cell size. But it seems to me like some kind of roll-out kevlar or dyneema netting could be really effective at protecting panels, though I think you'd need some kind of better strategy for safely dispersing the hailstones after they were caught, so you don't end up with a huge collection of hailstones on the net.
I agree that there's probably too much light blocking to leave them up continuously, and I'd also be worried about UV damage. But remember that the comparison here is to single-axis-tracking installations; I think automatic deployment of anti-hail netting could easily be made at least as reliable as the tracking system, if not significantly more so. Maintenance and testing would also be very cheap in comparison, since you could do it at night (ie without affecting power production), and damage to the protection system could be repaired without taking panels offline.
The more I think about it, the more I'd be interested in seeing it deployed.
Anti-hail netting is definitely a thing (protecting cars or fruit trees), for the reasons you state. Even big hailstones are rather slower than fast golf balls.
Hail damage at car dealerships in my area is so expensive that the dealers have added coverings for the lots (pretty sure highly encouraged by the insurance companies), and they are most definitely not nets. Nets would have been cheaper, so that should say something about their effectiveness (or not)
Hail protection nets are a COTS product. Full stop. Properly-designed nets are exceptionally strong; that's why we make "bulletproof" vests out of them (that's all they are, just a fiber net with a very tight weave).
Just because your local car dealership(s) didn't opt for hail protection nets isn't on its own evidence for or against their effectiveness. There are a great many factors that go into such a decision and, unless you were privy to the decisionmaking process itself, whether or not nets were considered -- much less their effectiveness -- is pure speculation on your part.
Ascetically, nets get dirty and are hard to clean, have birds on them, things grow on them, and they look gaudy to some.
Sorry, I don't get the joke. Nets can be pretty strong. Is it because there's a lot of hail at sizes big enough to do damage but too small for a net to catch without deep shadows?
i used standard chain link fence on top of my small greenhouse and it works even with such big "holes", no mechanism, just manual labor but needs good forecast which can be issue.
> it works even with such big "holes"
I'm intrigued. Can you expand more on this? Why does it work? I guess because the hail is rarely coming straight-on at the holes and instead makes more glancing blows off the wire?
In any case I think it's a perfect example of a good hack. Original out-of-the-box thinking producing an effective but unconventional solution. Chapeau bas!
i saw chicken wire used for something unknown to me on top of old 1800s greenhouses in France. it was not used for hail because it was resting directly on top of glass. i do not know what it was there for.
but hail and flying debris i got past few years is so big and so frequent that im not sure chicken wire will do the job.
a lot of gardeners use shading cloth for lowering sun light intensity. but that is not always enough to withstand hail.
A lot of times there is multiple pieces of hail stuck in one hole. some just bounce off.
i have PV on roof and not had issue with that. but i had few broken glass pieces of greenhouse glass. even tho it is on same property. it is glass-glass bifacial, i did not do it for back light but for longevity, i saw too many plastic backing tear off, or delaminated or how to call it. so i did not want that. and im not sure if that is also factor in not having broken PV.
doing it on huge PV areas should atleast be by my feeling too much of hassle, investment.
But some people mentioned in other comments small arrays of, if i remember correctly, 5kWp. so that is roughly area im doing it on. so in those small arrays it can be done manually.
https://99percentinvisible.org/article/fruit-walls-before-gr...
https://www.atlasobscura.com/adventures/trips/peru-machu-pic...
Chain link fence is a really clever solution!
well, makes goats not eat precious plants so if it can withstand them, then hail will be ez. XD
(neighbors goats. i do not like animals, too much worry and work around diseases. there are tens, some years even hundred millions of chicken burned because of avian flu, pigs have african swine fewer,.... no thank you, corona cave bats of 2019, was enough for me...)
So, a sloped half cone is ideal if you have the space?
This might be a dumb question but what about _compliant_ joints that expand and contract when warmed up by the sun? You can have any expansion multiplied such that minor changes in length are sufficient to track the sun in a meaningful manner.
No mechanical wear and tear and no wasted space.
I don't understand how east-west arrays differ much from just a flat area. At the end of the day, don't they capture all sunlight in some large square? The east-west array only captures a bit differently around the outer edges. Can somebody explain? Is solar panel efficiency that dependent on incidence angle?
The panel isn’t a perfectly flat two dimensional structure. So light hitting at an angle isn’t equally effective
I think this has been common knowledge for a while now.
The article fees disingenuous, flat panels collect the maximum sunlight from a given area of land and require fewer panels than the arrangement shown. Angling them helps the rain wash them and reduces the amount of mounting brackets unless you’re laying panels flat on the ground. Similarly total KW over the day isn’t why tracking mounts are so common instead it’s the increased value of electricity in the mornings and evenings so the actual economic benefits != total kWh.
However, the bit where it’s talking about increasing the angle means creating gaps between panels or the shadowing is going to offset any gains while also requiring far more panels and more land at which point you might as just angle the panels based on latitude.
everything is addressed in that article.
actually this is "bad kind of article", because there is so much information in there / "everything covered". that it is almost impossible to have comments about it lol.
It’s really not.
Literally laying them flat on minimally cleared land would win the simulation. Fewer panels, fewer acres, less mounting hardware, less labor, more power. Real world conditions not included in the analysis, such as wholesale electricity prices over a day and land not being flat, drives a lot of these choices.
How does using these the power from your panels to generate natural gas help solve climate change? Unlimited abundant natural gas sounds awful
Consider where that methane / natural gas is coming from. Their homepage says (with the world's most convoluted hyphen-omitting compound adjective, but basically see the last 6 words):
> March 2024: Terraform completes the end to end demo, successfully producing fossil carbon free pipeline grade natural gas from sunlight and air.
If you take carbon from the air, mix in energy from the sun to turn it into a fuel, then burn the fuel (undoing the reaction), where is the pollution?
There's more efficient ways to solve the climate problem than to install ginormous amounts of gas production, like you can run a heat pump instead of creating methane from that energy, but it's a solution that'll please even the old farts (no pun intended)
Not seeing the economics for this ever truly working out, CO2 PPM is very low despite our best efforts and the amount of energy required for separation is substantial.
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