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?
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.
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 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.
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
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.?
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.
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).
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.
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.
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.
> 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.
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.
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.
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?
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.
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.
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.
Readit News
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
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".
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 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.
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.
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.
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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.
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.
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.
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.
The insane energy density of fossil fuels means this is an excellent “emergency” back-up plan should the sun not shine often enough.
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'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.
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.
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.
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.
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.
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.
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.
During peak solar yesterday in California wholesale power was $5-6/MWh (<1c/kWh).
The CA grid is routinely over 100% renewables during springtime. The excess is handled by having a lot of batteries, exporting energy, and curtailments.
Space is cheaper than maintenance and breakdowns in many cases.
utility charges me so much for electricity that even tho i payed for 15 kWp roof mounted east west system literally literally ORDER OF MAGNITUDE more than prices showed in that article, AND i still save money by not buying electricity from grid !
that how much utilities are charging us, yes they need to manage all those wires, manage power plants, etc. i do understand where that cost comes from, but still, solar in residential is so cheap that installing PV on roof and directly consuming it will save you money.
So for industry/ manufacturing there will be extremely high incentive to add PV + battery even when it wont cover 100% of their loads. utility+ onsite PV+battery.
Again, back to my hot water system, 80% of year i am 100% "off-grid" for hot water [PV!]. even on days it is cloudy ! And 99%-0% of PV rest of year... And from april to October my electricity draw from grid is almost zero.
so whole residential USA can be essentially "off-grid" huge part of year with just small battery, your tv, notebooks draw almost nothing over the course of the day compared to your energy need for hot water. and less residential is on grid, easier it is to manage electricity for other sectors of economy.
this contraption from ETH Zurich can store iron/iron oxide to generate hydrogen, without storage loss! for years, without compressing hydrogen and without other cons of "standard hydrogen storage. essentially it can be thought about as hydrogen storage - it can "store" 10s of megawatts inside of a standard basement. - [https://ethz.ch/en/news-and-events/eth-news/news/2024/08/iro...]
and you do not need to make electricity from that hydrogen, you can heat your house directly with hydrogen, just by replacing 30$ 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 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.
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.
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
The only reason I can see for added complexity is if you're space constrained, and in almost all cases, not cost efficient.
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.
I have some pretty graphs at https://shkspr.mobi/blog/2020/04/comparing-solar-panel-gener...
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.
[1] https://news.ycombinator.com/item?id=42591918
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?
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.
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.
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.