Wow. So many better, cheaper places to put solar panels than random parking lots.

E.g. next to town out on cheaper land in bulk connected to the grid efficiently with large power substations.

This idea that "Hey! It's flat over here! Lets paste some solar on it!" is not any Engineer's idea. It some kind of green-theatre in my view.

The challenge is finding land with owners rich enough to fund putting solar there. A lot of big parking lots are on land controlled by big supermarkets or other retail outlets. So, stimulating those to invest in some solar is not the worst idea. As opposed to some land in the middle of nowhere with no-one with enough of a vested interest to make the necessary investments.

Making it mandatory simply causes these companies to start finding cheaper ways to get it done. And of course they lower their energy cost so it's not a complete write off for them. And parking lots are of course where people charge their EVs. So there's that.

> with owners rich enough to fund putting solar there

If you need to be rich to fund solar you are doing it wrong.

Solar is meant to actually pay back money, not cost extra.

There's no such thing as an infinite money glitch irl.

It's not infinite (what a low effort reply that was), there's a rate of return.

You don't need to be rich - you borrow money to fund your project, and pay it back out of the returns.

How so? Would love to get more info. I would have expected car parks to be a decent place for solar panels. Close to existing infrastructure, easy access, provides shade and no loss of habitat.

Exactly. Most airport parking lots charge extra for covered parking - parking lots could continue charging the premium and also make money generating power. Sometimes the free market needs a swift kick up the backside to do the right thing, it seems. (edit: s/Mostly/Most)

Covering parking lots requires a scaffolding structure to hold the panels. The cost of this structure is probably higher than the panels.

A much better plan would be mandating all large building roofs to be covered by panels unless unsuitable.

New commercial buildings are already required to have solar panels (or plants) installed on the roof: https://www.theguardian.com/world/2015/mar/20/france-decrees... https://www.architectmagazine.com/technology/france-mandates...

Close to power substations? Do they scale when you need more? Do we really want to mount our solar panels up on 20' poles? When it requires maintenance, do we shut down the parking lot?

It's clearly not optimal, not nearly.

Folks I know it's sad that every solar project that occurs to the layman, is not always a good idea. But don't blame the messenger.

Places with large parking lots usually also consume a lot of power and need a properly dimensioned connection to the grid anyways. And they will likely cover their own demand with these solar installations before they send any surplus to the grid.

Exactly. Those buildings next to the parking lot are another big problem - shade. In many cases the panels will be in shade part of every day. But Hey! the government says you got to put them up anyway.

This is a load of govt interference, down to virtue signalling and little else.

It only works in places without much snow.

If you need the solar-roof to also support snow load it's way way way too expensive to build.

For places with snow load you either put them on an already strong roof, or on the ground.

Put them at an angle so the snow slides off. And France doesn't get the meters of snow that you get in Canada.

Indeed - according to the article, the law requires a lot of parking lot surface area to be covered. Not necessarily by one gigantic roof, just as long as solar panels are blocking direct sunlight.

If there's snow plus freezing rain it won't slide off even at an angle.

If France doesn't get much snow, then sure, sounds like a good place for this.

Then you end up with a problem of clear cutting "useless woods" in order to install solar panels. While I don't think the French solution is flawless, it introduces an interesting dynamic.

Generally, I am against large surface lots (American style). So seeing someone introduce a simple incentive that both a) introduces a limit to their size AND b) offsets some of the blight for larger ones...

I am willing to see how well it works.

> Generally, I am against large surface lots (American style).

A bit of a tangent, but why? In my city they built a large shopping center without much parking, because that's what we do these days. Especially when the shopping center is basically next door to a large public transport hub.

The shopping center failed and declared bankruptcy after a few years. Main reason? No one went there because of lack of parking.

I think the US needs an honest assessment about the cost of such high degree of car centricity. There are layers of laws and regulations establishing car as a dominant method of transport, and actively discriminating against everything else.

In this current case, large surface parking lots are a terrible use of space. They generate very little taxes, contribute towards the heat island effect, and make the general area surrounding them less walkable.

The example you provided is definitely believable. I don't know a single modern (new) location that successfully changed the habits of residents from "more-car" to "less-car". And I don't necessarily have an answer what's a good solution. Having regulation like the French do at least helps nudge the outcomes somewhat.

> I don't know a single modern (new) location that successfully changed the habits of residents from "more-car" to "less-car".

The Netherlands did that (eg, [1]). It started in the 70s and is still ongoing. There were a modest few "quick wins", but most of the benefit is in the aggregate. It literally takes decades to get to a really different outlook/feel/vibe on traffic throughout a city/region, as opposed to only fixing accident hot spots. It's possible, with patience and tenacity.

[1] https://nl.m.wikipedia.org/wiki/Stichting_Kinderen_Voorrang

I agree than covering parking lots with solar panels is a good idea (except in places with lots of snow).

But I don't think America will ever transition away from the car - America is too big, and too diverse to make that possible.

Some larger cities may eventually have low rates of car ownership, but it will never be the majority of the country.

For example where I live there is an express bus to the airport - it take an hour. Or you can drive and get there in 20 minutes. The bus is cheaper (due to gas cost), and rather convenient you don't have to deal with your car at the airport.

But an hour vs 20 minutes? Ouch. (Oh, and that hour is if you drive to one of the pickup spots of the bus - if you need a bus to get to the bus then it could be an hour and a half vs 20 minutes.)

This is not something that's solvable as far as I know.

I like this approach of integration, rather than hoping there's land somewhere remote enough. There's also a lot of loss of efficiency with having the power transferred from land outside of town.

Transmission efficiency is negligible.

Look at google maps. Human habitation is a small part of the landscape in many places.

Solar farms are essentially portable - put them wherever they can be scaled, not interfere with existing infrastructure, convenient planned grid connection points at scale, and on and on.

No, this is not an Engineering solution. Folks latch onto this stuff as a sort of 1st-order plan. No, 0th order. With no thought beyond "Hey solar panels are flat; parking lots are flat!"

I reread the article. Seems that this is putting solar development on the public! No mention of govt assistance in buying/installing all this gear.

Are parking lots so profitable, they can support this significant cost? It seems a lazy law written by a lazy senate to get points in the press.

> Are parking lots so profitable, they can support this significant cost?

Costs are far more than offset by savings.

The savings in electric bills from schools with solar panels often topped millions in each district, and many have been able to adopt the technology without shouldering any costs up front.

“If you’re conservative, we didn’t ask you for more taxes, if you’re liberal, you love the green concept,” said Michael Hester, the school superintendent in Batesville, Ark., where solar arrays paid for teacher raises. “It’s a win-win.”

https://www.nytimes.com/2022/09/15/climate/solar-energy-scho... (archive: https://archive.ph/U5Alc)

In France, if it is flat, there is usually something there you don't want to remove, like buildings, crops, or a forest. It is not like the US where there are huge deserts with plenty of sunlight. Population density is 4 times higher.

On top of parking lot is one of the best place to put solar panels: shade and cover for the cars, easy access to the grid, and it is essentially free space. Probably a bit more expensive than in an open field but not by much.

It takes not much room at all to create a solar farm. A section of land perhaps. I see from Google Maps that many plots clear of construction surround Paris for instance, at a distance of a few miles.

Parking lots sound like an excellent place for solar panels to me, because they suddenly serve a second function: keeping the cars cool. On a hot day, people prefer to park in the shade for good reason, and this way, there's plenty of share on the parking lot.

Furthermore, parking lots are easily accessible for construction and maintenance, and it doesn't hurt any other use of the land. It's pretty much perfect. I'd say this is second only to rooftop solar as easy win for solar. And in some cases better than rooftop solar.

Also the added benefit of reducing heat soak for the parking surface too

> E.g. next to town out on cheaper land in bulk connected to the grid efficiently with large power substations.

Big box shops and malls typically have a close substation already.

So there are only half a dozen more significant objections.

No, this is virtue signally at it's finest.

"I expect a large increase in parking lots that hold less than 79 cars." -another hn commenter

* less than 80 cars

Let's give credit to geocrasher: https://news.ycombinator.com/item?id=33532383

Well, maybe disincentivizing large parking lots is a good thing.

I was thinking more along the lines of "My 300 car lot just became 4x 75 car lots!"

But I get it, it's a matter critical national economic security. I cannot think of an easier way for the government to massively ramp up energy resources without comparable ramp up in (government) budget. Offsetting a big chunk of power demand, even if that power isn't always when and where you need it, moves the needle big time.

If you have a large parking lot, you probably have a nearby large power demand, therefore you must throw some panels up ASAP. I would love to see this approach in a smaller format for the US. X sf of taxable retail space requires Y kWs of on-site solar capacity by end of 2023 to avoid an Alternate Energy Resource Fee. Start low, targeting 2% coverage of a typical suburban retail parking lot.

I would expect the government happily reduces the count limit to 70 in response

Big win for dogs who get locked in the car too.

I think solar cells get pretty hot. They're not very efficient, and they basically have exactly the smallest albedo they can have, so it's a pretty hot thing to make a roof out of. Hopefully they insulate the backsides of them.

A vehicle under direct sun will get hotter than if it's under a roof made of solar panels. Insulating the underside of the panels will reduce their lifespan.

tin works pretty well and it's a pretty hot thing to make a roof out of, having an air gap between your car and the heat source makes a massive difference rather than it being heated directly

Although I am not sure that fixed-position panels are optimal at French latitudes, this architecture is pretty nifty. Anyone know where it is?

https://www-publicsenat-fr.translate.goog/sites/default/file...

ETA: http://leclercsaintaunes.com/parking.html I guess.

I foresee big box stores constructing 4 isolated parking lots, one on each side of the store instead of one big one. The land for each one could even be owned by separate shell corps if needed. That would still be cheaper, less maintenance, and they don't have to worry about customers with tall vehicles.

They should be giving incentives for people to do this not beat them over the head with it.

France is not like the US. Trying to do this will get you in trouble.

I never mentioned France nor the US in my comment. Clearly this sort of thing is a trend and will be tried everywhere. That is what I was talking about.

In the U.S. there's a not very often used doctrine in taxes called the step transaction doctrine which says if taxpayers manipulated either the economics or the timing of a business transactions to obtain favorable tax treatment, the IRS may be able to tax the taxpayer as if they had not structured the transaction to avoid taxes.

Similarly if the French court or legislature wanted to avoid loopholes like this the law can be written to say, essentially "You created 4 different parking companies to avoid the regulation but we are treating this as one parking company for purposes of the regulation since you only structured it this way in an attempt to avoid the regulation, you had no other economic basis to do so, so you and everyone else part of this transaction are completely on the hook for following this law."

This is a matter of political will, of course. But your comment completely ignores the fact that the legal system can be designed not to have the loopholes you say will occur.

Wrong. Controlling people like this with law upon law upon law is a never-ending game of cat and mouse that will, in the long term, end with an authoritarian regime if no loopholes can be tolerated.

The lengths people will go to to resist doing The Right Thing (TM).

Related ongoing thread:

French senate: parking lots for 80 cars must be covered by solar panels - https://news.ycombinator.com/item?id=33532260 - Nov 2022 (97 comments)

What about parking lots with buildings on top?

And what about parking lots surrounding by buildings?

And what about the MOON? What are we gonna do about parking up there?! There are no rules! Mon dieu zoot alors!

I don't know about the moon.

I was thinking about parking lots that are already working and have a building or construction on top, that is not own by the same people. It is called here a garage and very common.

And the other question is about a parking lot surrounded by building that must to cover the lot with solar panels to get few minutes of sunlight.

I don't care about the moon