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Comment by jld | Hacker News Reader

It seems inefficient to put solar panels over parking areas as it requires significant amount of structure which costs a lot more than shade it creates is worth. Especially compared to how much less structure is needed on more remote solar farms.

Maybe I'm just using American mindset where there is lots of open land that is good for solar generation? Perhaps not true in Korea?

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Building solar panel installations in remote locations still requires linking that back to the main grid, and all the in-between infrastructure needed to transform and transmit that power. Building it in an urban location allows you to tap into the existing grid without much added public investment, similar to how some power grids will purchase power from homeowners as an added incentive for doing a home solar install.

Right, they actually have siting advantages over ground mounts for that very reason.

And let's not forget that they are investments, not just stranded costs (it's baffling to see them discussed that way to and down the thread). You get something back for having built them and the barrier to entry is the upfront cost, which is easier to overcome if you're a state spending on infrastructure.

The grid connection is very trivial. Connecting panels to the grid is as simple as adding inverter. For example in many places the panels provide electricity to location itself where they are installed.

> Building solar panel installations in remote locations still requires linking that back to the main grid, and all the in-between infrastructure needed to transform and transmit that power

Some people actually have an idea of how electricity works and statements like these make them think that the whole renewable energy industry is one big scam.

In your opinion, what percentage of the total cost is involved in tapping into the existing grid from nearest wasteland?

The really critical cost isn't monetary but time. There's plenty of places where the interconnect queue is holding up projects a lot: https://www.forbes.com/sites/davidblackmon/2025/05/06/study-...

Same in parts of the UK. Scottish renewables are bottlenecked on transmission to London.

Whereas connecting generation to a substation near demand usually shows up as "negative demand" and doesn't require big upgrades.

I'm an American, and it seems like a great use of land to me. This sort of a policy is particularly sensible in areas where it's hot, and there are extensive parking lots next to places that are mostly active during the day.

Instead of just having a heat island, you generate power to run AC in the associated buildings, and you also get shade for the parked cars.

I recently was at the Vegas airport, and what struck me was the parking lot.

It was the same parking lot I saw many years ago. But this time, instead of feeling sorry for the owners of the cars that were obviously getting cooked up, that whole are was shaded in bajillion solar panels.

It seemed like such an obvious win-win for everyone, I expect it to catch on fairly quickly.

But, isn't the albedo of a solar panel farm still way dark? It means the radiation is still being captured rather than reflected back up.

Capturing the radiation to convert it to electricity is the whole point of solar panels.

Even if it was just 0 albedo no generation, irradiation on whatever's parked beneath would be cut in half plus rest of (re-)radiation converted into far-ir. This is not unuseful. Just don't mandate this kind of thing in places where parking lots have to be cleaned up with bulldozers in winter.

If there are solar panels over the parking lot, then the parking lot doesn't have to be plowed. You can design the panels at appropriate slopes to direct the snow off the lot.

You're not looking at the albedo of the solar panels in isolation though, you're comparing it to asphalt and cars. Typical solar panels have an albedo of ~0.3. Asphalt around ~0.05.

There's a reason centrally planned economies are abject failures. People are incapable of anticipating all of the cascading effects of a "sensible" policy

Well, yeah, that's how we got cities with a huge amount of land dedicated to economically parasitic parking lots in the first place.

That seems like a confirmation of the point more than a refutation. The parking lot problem is not a free market phenomenon, it's a result of regulation's unintended side effects.

This is also a feature of distributed economies; it’s just the communication overhead to make a change centrally means that bad decisions are less easily repaired. AI and electronic data feeds seriously could be tried to fix this. There are good advantages to a centralized economy… the trick is getting the objective function right.

And it’s not like modern capitalism has done a good job of that anyhow.

>It seems inefficient to put solar panels over parking areas as it requires significant amount of structure which costs a lot more than shade it creates is worth

If you're putting up structures to shade cars from bright sun anyway then it doesn't take a lot of legislative pressure to enforce "the thing you put up has to be solar panels".

Not familiar with SK, but in principle this parking shade had better be panels works. This is doable within both governmental, social and financial frameworks in countries that get decent sun. Whether SK qualifies as "decent sun"...idk...seems borderline to my unqualified eye

Most people driving around in a big city don't have the luxury of choosing a shaded vs. sunny parking space. So the owner of a parking lot doesn't have any incentive to offer shaded parking... unless said shade generates revenue, which a solar panel does.

In a city the best place to put them first is roof tops. Rooftop solar has minimal structural requirements relative to parking lot canopies.

I think this might be partially an indirect tax on parking lots inside a dense city. It raises the cost of using land for parking, but does so in a way that provides shade and clean energy at the same time.

Ground level solar in a big city doesn't make much sense, they'll be getting a lot of shade- which significantly reduces the power generated. They've made new panels that are better with partial shade, but it's still crazy.

Most parking lots in big cities are not surrounded by high-rises.

Well also when they are they are small parking lots. This regulation specifically is for big public parking lots.

Also the "surrounded by high rises" locations are more likely to be built as parking garages in the first place.

Low rise or high rise, (near) ground level (sub)urban PVs are going to run hotter because of the heat island and disrupted breeze, so panel efficiency and lifespan will take a non-zero hit too

High rises are expensive to build. The reason they are built in the first place is that land is even more expensive, and expensive land militates for parking garages rather than open parking lots.

> In a city the best place to put them first is roof tops. Rooftop solar has minimal structural requirements relative to parking lot canopies.

Why do you assume they haven't been doing that already?

A flat parking lot is already a ridiculously inefficient use of resources. Putting solar panels on top directly improves quality of life (through shade) and claws back a bit of that inefficiency.

South Korea is pretty mountainous so yes, available land is much less compared to America where we have square miles upon square miles of open land. South Korea is little less the size of Kentucky.

South Korea has a population density of 507/km² [1]

For comparison, the San Francisco Bay Area has a population density of 430/km² [2]

I doubt they have vast tracts of undeveloped land. And while solar panels can replace agricultural land or wooded areas, doing so isn't always a big political win.

[1] https://en.wikipedia.org/wiki/South_Korea [2] https://en.wikipedia.org/wiki/San_Francisco_Bay_Area

South Korea has tons of undeveloped land. Just look at an aerial imagery map. It’s just that it’s quite mountainous and heavily forested. (Not that I think we should tear down the forests for this - surface parking lots are already an inefficient use of space)

It seems inefficient to not put solar panels over a parking lot. I'm not sure how shade is a major consideration here or how light weight solar panels are a large expense compared to the cost of space in a city. Parking garages are often net negatives to cities and parking lots are generally major negatives to cities since they drive density down and reduce foot traffic (which reduces economic churn). At least this way the city gets another small use out of that area in the form of some local electricity generation. Density and variety of use are major factors in urban health.

It doesn’t really matter if there’s land that would theoretically be more ideal if the value of the power generated pays for the infrastructure buildout. The best land for solar panels is the land you can build on now.

Something like 70% of the Korean peninsula is mountainous, and a lot of the space between mountains is taken up by cities and farms. This puts flat land at a bit of a premium

Dedicated parking areas are hugely inefficient in the first place from an economic perspective, so this is at least getting some double duty out of them.

It adds utility to an arguably less useful use of space (shut up, I used use two words in a row and twice here), minimizes transmission costs and losses (the power is needed right there in the parking lot or where the people parking there are going to), and doesn't displace other land use (farms or nature).

Correct. There really isnt “more remote” in Korea because it’s such a small nation geographically speaking. You’re never more than a few hours from the farthest border.

Yes, build far away and wait 30 years for transmission lines to be built or to be connected to the grid.

Building where people live means (near) zero transmission infrastructure.

I don’t think it’s that much more - it’s really just extending the length of the pilings used in regular ground mounted utility scale solar?

https://news.ycombinator.com/item?id=47559893

it seems wildly efficient to use the massive amount of dead space we cede to cars. Without cars, parking lots are just massive heat sinks that trap and hold heat. Might as well do something with them to make it a little bit better. It also has the added benefit of creating shade for people in the summer and cover during rain.

So often though, they are obstructed by nearby buildings.

maybe in some areas, but in the suburbs? they will get plenty of light covering the parking lot of a wal mart or target.

Agreed. But in the suburbs, there's no lack of good locations to place dedicated solar farms without obstructing traffic.

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