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Obvious choice
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this post was submitted on 21 Apr 2026
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It's probably a good idea to put solar panels on car parks where we're going to have car parks anyway, though. In addition to agrivoltaics and using, as you say, substandard land for large scale solar. Also put it on roofs. Basically anywhere it doesn't do any harm, I say.
Governments should encourage every home to have at least enough solar powered energy to run a small refrigerator, a space heater, a small cooking surface, and a radio as a matter of national security. That can be achieved with porch solar and significantly hardens a population against attacks on energy infrastructure.
Would also require an isolation switch to be effective. With a grid-tied solar install it's going to dump all of the energy into the grid, and during a power outage that energy will simply not be collected.
I could see that becoming a thing where during a power outage you flip a switch near the electrical panel and then every green-colored outlet will run entirely off the solar panels when the sunlight is available. Or if we really want to make it technical solution, create special outlets that are dual power (grid and direct from solar) and then appliances plugged into these special outlets will switch between power sources as they're available. Potentially some issues with two different AC circuits touching depending on how it's implemented on the appliance side, but it could be a good solution especially if the controller can still backfeed excess energy production back into the grid
You don't need that switch. There are already automatic switches. And if you have batteries you can load them from the panels and, in case they go too low, from the grid and then use the batteries to power your house.
We already have hybrid inverters that does that automatically, you don't even need a different circuit or special outlets. It can manage all the grid ties, off grid and battery parameters on the fly
Well shit that's awesome! Like I'm kinda curious how it handles the load exceeding capacity, but I suppose if you just turn everything off that should probably be fine
As in what happens if you plug too much stuff that it exceeds your solar production?
I'll use mine as an example, but it might be different with different models and configurations:
Inverter can handle up to 10kw
If solar production is at 5kw, and home is demanding 7kw, in my case, I have it set up as to draw the remaining 2kw from the battery, if battery is depleted, it will draw 2kw from the utility company
If home demands more than 10kw that the inverter can handle, it will trip the internal inverter protection or a circuit breaker leading to it
I want to do something like that but just have the solar circuits entirely disconnected from the grid, running stuff like fridge, freezer, water heater, car charger, etc (depends how many watts my panels can actually manage in practice; I don't have a ton of space). all without being able to draw from the grid at all.
My state is pretty shitty about solar, and I don't particularity want to give the electric company my surplus power for free for them to turn around and profit from, so fuck ‘em, ill figure out how to perfectly balance my use with my capacity and just save the spend.
With the current prices of panels you might install a few more than needed.
That's so fucked up. Even people who install solar have to give free energy to the utility company, who probably still charge them for energy...
Yes, thats exactly what they do. No net metering, no discounts or rebates, nothing, but if your power flows back into the grid, they sure will charge for it at the exact same rate as if they created it themselves, and charge you as much as they can get away with to eat into your savings (some utilities around here even make you pay a monthly fee to have your own solar on “their” grid..). No surprise hardly anyone here has solar; it’s generally not worth having unless you can guarantee you use all of the power yourself.
My locality is mostly hydro power, we don't even really have peak/off-peak rates, just pay the same all the time regardless because they can’t easily adapt to demand anyway. And like yay renewables and stuff, I'm super on board with that aspect, but I'm not on board with having a monopoly on the renewables, since my area is not typical of the state.
That's absurd. People should use repurposed EV batteries and just power their homes on solar without connecting to the grid. I get that it's probably a legal requirement to connect your solar to the grid, but that's bullshit and nothing short of state-sanctioned theft.
Exactly why basically that is my goal :)
I’m technically too urban to be entirely off-grid, legally, but I see no reason I can’t minimize my draw with a separate breaker system. Whole place needs to be rewired anyway because it’s ancient. Knot and tube ancient.
But most people aren't willing to go through that, and I cant blame them because there aren't any incentives to doing so, and most people don't realize how much cheaper used solar farm panels are, so it just seems like a really bad deal. And for most, who would have it installed for them, new, maybe thats true. Used with mostly-self-install is much cheaper. Even better if the whole deal needs to be re-wired anyway.
Except most solar systems go down without power from the grid
Imagine a roof on the highways with solar panels.
I would say let’s maybe not have car parks at all? They suck. We should as a species try to phase out personal cars, first of all. And secondly, until then, underground garages are infinitely better for everyone else.
OK, so in 100 years you get your wish and personal cars no longer exist. For the next 100 years, would you like to:
In addition, after 100 years on top of the car parks that still exist (perhaps for the shared cars), would you like to:
The only problem is adding solar to car parks will ensure that those car parks remain there. Surprised to see so much support for this in the solarpunk community of all places.
How about we get that wish in, say, 10 or 20 years instead of your strawman scenario? Transforming cities to be walkable/bikable does not take that long, if you're serious about it.
Personal cars are going to be here for way longer than 20 years, but 20 years is still long enough to build a lot of solar panels, so the same questions still arise. What will your answer be?
Tops of buildings, over canals, may be even over roads and rail.
It isn't that far out of reach that a car park gets covered in solar panels, then the next developer reuses them when redeveloping the site for denser development.
You forget that people live also outside of cities. If you live in a town away from any city you need a car.
No I didn't. First of all, forgetting and disregarding aren't the same thing.
Second, living in a small town isn't an excuse. Small towns are inherently walkable (due to being, ya know, small) unless you somehow manage to design them spectacularly wrong. And contrary to American belief, it is actually possible to provide rail transit to them: the US itself used to do it 100 years ago, and Japan still does.
In Spain, where I live, there are town (<1500 people) that have the closest supermarket art 25 km of they are lucky. And no bus or 2 in the day with the schedule for the kids.
First of all, how close is the closest non-super market? I mean, I could say "omg I've got to drive 20 miles to get to the nearest Costco" but that doesn't give me an excuse to pretend the Lidl in walking distance doesn't exist.
Second, even if there really isn't any way to get groceries without driving 25 km, just because some particular town is designed stupidly and lacks necessary services locally now, doesn't mean it has to be that way in the future. It's somebody's fuck-up that needs to be fixed, not an immutable natural law inherent to how small towns work.
You haven't lived in a small town, right?
That’s a false dichotomy. I can choose a third option. Where we place car parking garages (multi-level above or underground) all around ring roads and ban cars from entering city centers. Then we put solar panels on top of most roofs, and in fields for grazing animals.
This obsession with car parks is exclusively American.
So you want to demolish all the car parks that already exist? All of them, tomorrow? Don't you think it will take some time before the builders can come and replace the last car park in your country with whatever it's going to be replaced with? During that time, would it not be better to put solar panels on it? (And then remove them before it gets demolished and put them somewhere else)
I am not American, I just think it's a stupid criticism of such a plan that we "shouldn't have cars and therefore shouldn't have car parks" because the fact is that we already do have them so we may as well use them as best we can.
In any case I don't agree on a total ban on cars entering city centres, at least not in the foreseeable future. The most bike-friendly cities I have lived in and visited have also had many cars. I suspect there is a place for personal cars, deprioritised compared to buses and bikes, in most cities for many years to come. During that time there will need to be car parks. Those car parks should have solar panels on, along with pretty much all other buildings.
Many cities have already banned cars in their centers. It’s not a “what if”. It’s been done and works. And it takes as long to build those garages as it’d take to build those solar parks. And not like they couldn’t be done at the same time. Like instead of building solar over the car parks, why not spend the time and resources building them over warehouses and apartments?
I don't know of any big cities that have banned cars from anything but small areas in their centres. I know that in my city, the centre of which is pedestrianised, nevertheless has many car parks, including two large park-and-ride facilities with large car parks that could have solar panels installed.
The reason to build them over car parks is because the ones being considered are surface-level, so any building work is cheaper and easier. And it also provides a benefit to users in the form of shade.
Ultimately we should indeed aim to cover rooves with solar panels, but let's focus on the lowest-hanging fruit.
The USA has a stupid relationship with car parks, yes, but I'm not American and I'm not encouraging car parks at all, I just think we should put the space where they already exist and are actually useful to better use.
Ideally, yes, we'd have much better public transit infrastructure but it'd need to be every ten minutes on every route and not stop overnight or for Sundays or public holidays for it to be a viable replacement for a car for me. Which is very feasible in a big city but not so much out in the countryside.
Ultimately, some people will either always need personal cars (or perhaps some other solution, but no public transit I've ever seen will do it) for a huge variety of reasons, including disabilities and house locations (and I don't mean suburbia, that's generally solvable with public transit and also generally a bad idea).
Except in places where you can’t go below ground because of water, of course.
Well there are above ground parking garages as well…
Well, we could also stop adding a certain percentage of biofuel to our cars. The land that we gain from that, if covered by solar panels, would produce enough energy to cover all our energy demand.
Also a great idea. One of the things I think is good about putting it everywhere, though, is that it cuts transmission requirements+losses and increases resilience by having the generation be localised.
Eh, we’ve done pretty well with transmitting power. So although I do agree that spreading the load is always better, it should not be compromising the costs. As putting it “everywhere” also comes with some downsides.
Transmission losses are quite large and long distance transmission lines use fairly limited resources. Just getting a grid connection is the bottleneck in renewable projects in the UK right now.
Good idea on a paper, but its expensive to build steel frames for the panels and there is the risk of somebody crashing and making expensive mess.
Also maintaning and cleaning anything elevated is a bitch.
And parking need resurfacing or at least repainting of the lines everynow and then.
Another way to think is that if covering parking lots with shade would be easy and viable we would have much more of shaded lots without solar panels allready.
Brazil had tons of shades for their car parks, I thought it was really interesting.
My area has a lot of solar in parking lots I think maybe because permitting is easier, plus then you don't have to put holes in your roof that causes even more leaks possibly.
The school my wife works at had a truck crash I to their solar and brought down like two big panels so definitely a safety concern
Covered parking is normal in different parts of the world actually.
And its more necessary in some places of the world.
Like triple-glazed windows are norm in different places of the world. Most places could benefit from those from purely energy conservation point, but in some places the benefits dont justify the cost and the effort.
Yeah, I'm largely spitballing. Perhaps the numbers don't work out, perhaps they do.
That said, solar over parking is a source of income. It may well pay for itself whilst providing parking that is both shaded and rain sheltering and improving energy security and helping fight climate change and probably powering a bunch of charge points underneath it, which you could either charge for or just leave free to encourage people to come to whatever the parking is attached to (or just the parking itself if it's a paid car park). My local Sainsbury's has a free charging point and it's a big part of why I shop there.
Also design the canopies to be their own scaffolding so the elevated maintenance is moot.
You can resurface under a canopy. Hell, petrol stations are almost always under a canopy and they definitely get resurfaced sometimes.
There's a risk of someone crashing into any building, too, but we still build things that are useful beside roads.
I'm just saying that, yes, it's not cut and dry, but I'm pretty sure the problems with the idea are generally solvable.
Solvable but not financially sound. Im not arguing that its a bad idea and that we should not do it. Im arguing that from the financial view its not profitable, so there is a reason why its not happening.
Oh wow. This is going to be a long one. Sorry for this and thanks if you take a time to read it...
Of course you can. But lets imagine you are a contractor. How much more you would charge doing a clean parking lot versus parking lot with lots of beams and high voltage equipment both over the head and under the pavement. Especially if cant bring larger equipment to there?
How about when you think about your business that uses that parking lot for the customers, how much it would cost to keep the lot closed for a two days it takes to resurface it instead of one.
But lets solve it by making the canopy larger, so they can use the bigger machinery and do what ever resurfacing they need with close to same price and nearly as fast than just a plain old flat parking space.
Now the initial building cost starts to multiply because larger structure needs more materials and things like wind start to effect more. Oh, higher canopy means the shadow is not on the parking spot anymore. Well we can live with that, or we can make the canopy wider and add more panels. It just means we need more and sturdier, more expensive material to do that. Well do it or not, the higher canopy makes maintaning the panels harder and more expensive, but wait we made the canopy to be its own scaffolding, that surely does not add to the building cost, engineering and designing is free and afterall. You probably need to close few parking spaces everytime maintanence is happening anyway.
Well lets say anything before this is non issue and there is enough panel coverage to justify the cost and maintanance. Rainwater has been easy to direct to right place and the structure can handle the weather, wind and possible snowfall, the electric cables and battery system were easy to place maintain and they are not fire risks and the project produces enough energy to justify the expense.
What happens with insurance. We have build rather expensive and delicate system in place where people of all ages drives around. What happens when somebody bumbs in to the supports keeping that whole thing upright. What if somebody crashes and part of it comes down. What if the maintanance guy takes a fall. Well in every case you, the owner of the lot need to either stop what you are doing and start to jump trough hoops, or you need to hire somebody to do so. Even if you are no way in fault, you need to make sure everything is structurally sound and spend time with the situation.
Well crashes happen. Lets not dwell on it. Lets focus on the good part. Free electricity. Is there enough of it to justify the building cost and the maintanance of this new system? Lets say there is and everything is fine and dandy. Who uses the electricity? Do i own the whole place and run my own business there. Great! I can use the electricity and even sell the excess. Or maybe there isint that much, but i can put few Evehicle charging ports there. Do they and the shade they produce bring enough business for me to justify the cost of building this canopy? Who knows. But wait. Arent most of the busineses renting their premises. Do i sell the electricity to them or just sell it on the open market. What kind of paper war i need to do so the lease is fair to everybody even if there are times when the panels dont produce because of the weather. Sounds like it could be headache. Well lets not worry about that either. Im sure the paperwork will solve it self. Alltough there are also plenty of places where the parking lots are owned by completelly different entity than the busines near them.
Now lets say all of the above is solved and ask the big question. The reason why i think we dont have these things build.
How you as a business man, justify all this, when you could spend the same amount of money renting or buying a lot of land somewhere else and have the same amount of solarpanels build with smaller maintanance costs in less accident prone enviroment and keep your parking lot as it is? Realistically it would be better to use that money on something else.
Only way i see this could happen is busines owners want be green or if they get tax benefits or something from it.
I think solarpanels on the parking lots could be nice, but i dont see a lot of incentive for doing it on big scale. I think most busineses would do better if they build just normal light weigh, easily movable canopies and just out the panels on the roof or the walls.
Thanks for reading my bullshit and sorry for any typoes in it.
What is the electricity bill of a supermarket? How long would pay itself a solar root on the parking lot?
All fair. And, to be clear, I'm suggesting it be mandated or incentivised by governments, I'm not suggesting businesses would do it on its own merits. Though I wouldn't be surprised if it ends up being a good idea for them in, say, twenty years time, even with all of the complications.
Solar panels are less efficient the hotter they get. Heat makes the electrons in the panel bounce around more at rest, which means they can't be excited as much from the sun's energy. Throwing them in a concrete desert with hot cars parked underneath would probably affect their performance significantly.
Yes, I'm well aware of this. There are plenty of locations where that's not really a problem, though. And generally when they're hotter and therefore less efficient it means there's also relatively abundant sunlight, somewhat counteracting the effect of the heat. Cars also aren't necessarily that hot, particularly if they aren't powered by burning stuff. And putting all of that under the shade of a canopy would reduce the heat reaching the ground. If you used a brighter paving material like concrete, you could even benefit from bifacial panels using the reflected energy.
There are problems and there are solutions, maybe the problems outweigh the solutions but it's still a worthwhile avenue of research to find that out.
All I'm saying is it would make more sense to put them over agricultural land than in parking lots.