Covering parking lots with solar panels | Hacker News Reader

Covering parking lots with solar panels

washingtonpost.com

111 pointszonotope63 comments

Ever since I first saw one of these -- several years ago, near the Googleplex [1] -- I have had this idea for a real-estate venture. You're welcome to take it on, because I'll never get around to it. Step 1, go into AZ, somewhere not too far from Phoenix or Tucson, buy some cheap desert land near a freeway exit. Step 2, grade the land and gravel it, never mind asphalt, no need. Step 3, good high security fence around. Step 4, Put up solar panels like these, but raised good and high, 20ft clearance under. Step 5, advertise "Shaded RV Storage". Charge people a good rate for storing their RVs where they will not be so horribly sun-damaged, as many RVs are damaged by long-term sun exposure. Meanwhile selling power to the utility. And, bonus, put gutters along the lower edge of the tilted panels, leading to a buried cistern, collect rainwater water for pretty landscaping and for washing RVs (for a fee, your RV will be all sparkly clean when you come pick it up).

Yer welcome.

[1] Street view https://goo.gl/maps/2T8mZ

I suspect the trouble with the idea is that selling power to the grid and selling RV parkings becomes more difficult and costly as you get further from areas where real estate is desirable. There may be no point where the cost of land+panels and benefit from electricity+parking sales work out to be a reasonable investment.

That's precisely what utilities are doing (well, without the RV storage part) https://gigaom.com/2015/01/20/a-special-report-the-rise-of-a...

You need to account for delivery risk (is there enough grid of enough capacity?), legislature risk (right now utilities are sort of forced to buy back the kilowatts, but in different legislative climate they might refuse or offer you an unreasonably low rate because hey, it's a buyer's market) and environmental risk (this will likely displace some native species like tortoise).

Feasible? https://www.youtube.com/watch?v=HOZBrHqTJk4

In the gp's post, he's talking about above ground mounting, similar to rooftop, and more like the parking lot coverage in tfa... in this case it's actually about a break even for the solar in 8-12 years usually... (feel good qualities not withstanding)... that covers the electrical usage for the lot's residents, at the very least. Assuming you are charging for the electricity... you are still making the lot rent, and on top of that, you can charge more for being a "green" lot (if the organic food market is any indication), which means you can charge over 20-30% more than standard lots... so your break even on investment is about 8-12 years, but you'll be making 20-30% more on the lot rent, which means you'll probably break even much sooner, and see a close to pure profit for 8-10 years after the investment paid for itself.

It's not a bad system... this also doesn't account for states like Arizona and California that offer tax breaks and incentives for solar initiatives like this one.

Great idea. I always thought there's a lot you could mix with solar. How about wind and solar? Surely the shadows of the turbines wouldn't be that bad.

I drove between Tucson and Bisbee (about a 2 hour drive) last month, and the number of RV parking places there is just astounding. I could definitely see this working.

The RV owners that boondock a lot usually have 700+ watts of solar capacity, and some of them are starting to add LiFePO4 batteries instead of AGM lead-acid. So you'd want some portion of that area open to the sky for them.

But for those who don't have solar panels, this could be a good thing for them - they get shade, and the park has lower electricity costs (RVs typically have 30 or 50 amp electrical needs). Ideally you'd have some form of energy storage to supply power at night to them.

The RV owners wouldn't even have to extend their awnings, if you did it right.

Here in Japan, virtually ALL parking in lots is hourly metered. You get a ticket & if you spend money in the stores, they will credit you the price of the parking (making it cheap or free for actual paying customers) on the ticket. This is actually done for reasons of space - cities are crowded & and space for parking is at a premium. The result is that it is just considered normal.

In the US, they have these massive lots that are spread out over an area often larger than the store itself. The obvious thing to do would charge for parking with the Japanese system, and use the proceeds to help offset the initial costs, just like with a toll highway or bridge.

However, the "God-given Right to Free Parking" mentality would never allow it to work, and the local governments are too weak to try to impose it. Every city has a ring of malls outside of it not just for cheaper land, but to escape any form of regulations from the city itself. This is a "risky thing", and businesses don't like risk.

It would take a very careful marketing campaign to be able to kickstart something like this. I doubt many places have the leadership required.

The lots are privately owned by the malls, shopping centers, or stores. The "city" is in no position to impose paid parking on private property. Where parking is scarce, private parking is generally not free. Where parking is provided on public property (e.g. city streets) it is often metered, though certainly not always.

While they can't directly tell a mall "you have to charge", they can encourage it indirectly through zoning laws:

For example, they can cap the footprint of parking lot space, leading to stores building parking garages or taking their own steps to minimize freeloaders through metering. That's just an off the top of my head example.

Never say the govt "can't do something". The have power of eminent domain, as an example of how far they are able to go when the actual will is there to have something they want. Check out the history of the new Fenway Park for things they can do.

Rather than a cap, many suburbs have a minimum parking space requirement for stores. Suburbs have been using zoning laws to encourage a car based economy. In the Chicago suburb which I used to live, you could not walk the one mile to Target even if you wanted to for lack of sidewalks, crosswalks, etc.

The city already legislates how many parking spaces the mall should have, so you can't say there's no civic control over private parking.

Why couldn't our city councils tax each parking space? Landlords would pass that on as a parking fee.

Maybe because both the property and the commerce these spots facilitate is probably already taxed and that's already passed on to consumers.

Just because something supports commerce doesn't mean it should be free. My city (Mountain View, CA) has outlawed plastic bags and requires stores to charge for paper bags...commerce supports that were "free" to the consumer in the past. Yet, for some reason, the city provides TONS of free parking in municipal lots.

Car owners kind of already pay for infrastructure for their vehicles through excise tax, gas tax, and tolls (not really, but at least its something). Why not charge for parking too?

>The "city" is in no position to impose paid parking on private property.

so many other things are imposed on private property, so I don't see why suddenly paid parking is the "limit'

A good start would be for some cities to abandon their minimum parking zoning restrictions, which actually exist.

> However, the "God-given Right to Free Parking" mentality would never allow it to work

Um, most cities in the US have metered parking, too.

It's only when you reach the suburbs that parking changes to free. And that's because, with prevalent car ownership, having to pay for parking will decimate a store's customer base.

Even most metered city parking is far below what the "free market" rate would be.

a lot of parking lots in los angeles are like this.

> with the Japanese system, use the proceeds to help offset the initial costs, just like with a toll highway or bridge.

The U.S. system isn't free. The cost is embedded in the goods/services you buy. The Japanese system just removes the freeloaders, because parking is so abundant in most of the U.S., we don't really have that problem.

Although, I have found myself parking in weird places to avoid the valets. Valets now seem like some requirement everywhere I go, in my city at least. I feel like it's actually a disservice in most instances so I try to revolt when I can.

You only see that in densely-packed areas, though. I also live in Japan, and have spent a very large amount of time out in Saitama[1], where for the most part, parking is free as well.

Where I live, parking works as you describe.

[1] The prefecture next to Tokyo, for those that aren't deeply immersed in Japanese geography.

The High Cost of Free Parking: http://www.uctc.net/papers/351.pdf

Parking is free? Tell that to the parking lot in downtown LA a few months ago that was charging me $5/hour.

"The obvious thing to do would charge for parking with the Japanese system, and use the proceeds to help offset the initial costs, just like with a toll highway or bridge"

So, why would I pay for the cost of something that makes money for the parking owner again?

That's ridiculous.

I'm not too aware of payback timeframes and maintenance costs of solar power. So I thought I would look into the Rutgers solar canopy. This led me to the news article at Rutgers discussing the project:

http://news.rutgers.edu/news-releases/2011/04/rutgers-board-...

The description largely matches this article in the Washington Post. It also mentions that it was a "40.8 million dollar project." I'm uncertain if this includes various tax breaks and incentives, but let's take it at face value.

It also mentions that it will generate 1.2 million dollars per year in electricity. If we assume that electricity costs will stay perfectly constant and that maintenance costs are factored into the 40.8 million, this means the facility would pay for itself in 34 years.

I do not actually expect maintenance to be included. I ask myself, how long does a solar panel actually last? It seems many tariffs and incentives are based on a 25 year life of a solar panel. The UK Centre for Alternative Technology has the following article: http://info.cat.org.uk/questions/pv/life-expectancy-solar-PV...

In it, they explain that a solar panel's output will go down by about 1% per year. The materials surrounding the electricity production will wear, yellow, or otherwise decay, but the power production seems largely unaffected for 30 or more years (aside from the 1% decrease each year, that is).

On the flipside, energy costs are rising at much more than 1% a year. So in terms of raw energy pricing, and assuming that maintenance isn't too much of an issue, it seems like the Rutgers facility might "pay for itself" in 35 years. Of course, it isn't exactly a good fiscal decision to freeze $40 million dollars for 40 years.

I have no idea how to quantify the benefits of shade for the cars. But overall I now have a basic understanding of why someone might build the Rutgers facility.

It also seems likely that as energy costs rise, solar panels become less expensive and more efficient, then these canopies will make much more financial sense. It seems like it would take a lot for it to be a "good money investment" though.

I also have no idea how to quantify the benefits of shade for cars, but want to point out that they're non-negligible. Everything ages faster when exposed to sunlight and heat -- your paints will fade, the rubber bits will lose their flexibility and crack, your vinyl seats will slowly evaporate. There should be a measurable difference in how long a shaded car lasts versus an exposed car and a savings for taking better care of your car.

"On the flipside, energy costs are rising at much more than 1% a year."

http://www.nasdaq.com/markets/natural-gas.aspx?timeframe=10y

huh?

Perhaps electric rates would be more relevant than natural gas...

http://www.eia.gov/electricity/data/browser/#/topic/7?geo=g&...

There seems to be more to it than that. The article also says: "At the end of a 15-year lease term, Rutgers would purchase the facility at a fair market value – an estimated $3.6 million." And "The combined value of the SRECs and electricity savings are projected to net Rutgers $28 million over a 20-year period, exceeding all costs to the university."

So I'm guessing that about half the cost entails (re)paving the parking lots themselves --which they would have to do regardless of the solar canopy.

We had a wonderfully spirited debate about this inside of Google when I was there as Google was putting panels on their parking lots and the question of payback times came up.

Disclosure: I've had 5.2kW of solar panels on my roof since 2001.

You can do the "simple" computation, which is to take the cost of the installed system, add annual maintenance, use the expected generating capacity, multiply by the kWh charge, and then point at the place they cross zero.

The first problem you have with that is the price per kWh is not constant, it is higher during the day (peak) and lower at night, you can choose to use the peak power rate as panels in California generate their rated power during the period the power company considers "peak" time.

The second thing is that panels in the Bay Area generate rated power from about 10AM to 2PM, and depending on conditions some amount before and after that. My panels "come on" when the sun comes up and depending on fog hit their rated power between 9AM and 10AM in the summer, closer to 10AM in the winter (Sun is lower on the horizon).

When we installed the calculation was 5 solar "hours" (peak production) * net capacity (about 4.8kW) to get 24kWH per day of generation (nominal) which matched our nominal daily power usage. In the fall our panels do 18 - 20 per day, in the spring 28 - 32 per day. At $0.20/kWH about $1750 in power per year and about 11 years for the costs to meet at 0 (they were $19,000 installed after rebates and what not).

So that is the "simple" version. Other things we might have considered (but didn't actually)

Had we invested the $19,000 in 2001 in the S&P 500 would we have doubled our money by 2012? Answer nope. Although we're getting close these days.

How much "more" is the resale value of our home with $20,000 of panels on it? $20,000? $0? Hard to tell in the Bay Area because prices are just crazy anyway. We have had a couple of solar equipped houses in the area sell and the realtor that lives across the street seems to thing there is a premium but can't really say if its washed out by changing opinions on the public schools.

Cost of Maintenance? Our panels are "grid tied" which means they push power into the grid when the home is using less than they are producing. Other wise they contribute what they can to the existing house load. So maintenance consists of going up on the roof and hosing them down every 4 - 6 months to removes dust, and trimming a tree in our front yard which would shade them if it got any taller.

AC Costs? We don't have an air conditioner (we insulated the crap out of the house to maximum thermal efficiency) but the panels do cut down significantly on the heat load in the attic. Prior to their installation we had an attic fan that would being cycling the air if it got about 100F in the attic and it would run probably every other day in the summer but runs perhaps 6 to 12 times per summer these days. Not a "cost" but the house is more comfortable.

Carbon Footprint? No even though we've been less responsible (via fossil fuel electricity) for generating CO2 it isn't easy to compute the cost of that and figure out how it contributes to the break even point.

The warranty on the panels is 25 years (although I've mentioned elsewhere that we had to swap one with a Chinese panel as Sharp cannot replace like for like and that would impact the entire system). The inverter warranty was 10 years, they are going strong. So do we run it for another 10 years and then use the money to buy replacement panels? Maybe. I've been considering redoing them now (current generation panels are quite a bit more efficient than the ones I have, so moving most of my current system to a ground mount and replacing the roof panels I could probably get close to the PG&E cut off of 10kW)

Given the lower cost of current panels (especially pre-tariff!) I expect that if they are grid tied they pay back their investment in under 15 years here in the Bay Area. But until I price the replacement system I won't have solid numbers for that.

I was in Qatar this summer and noticed them. Anyone know how long this has been installed there?

http://www.qf.org.qa/content/the-foundation/issue-68/qatars-...

QF’s solar project has also brought parking lot shades covered in solar panels to Education City – the first in Qatar – and achieved the first agreement to be signed by Qatar General Electricity and Water Corporation (KAHRAMAA) that accepts a private commercial energy project’s connection to Qatar’s central power grid.

looks like the following company has been providing this type of construction since, at least, 2012 when this article was published (the company looks like it's been around since 2006).

http://envisionsolar.com/press-releases/envision-solar-annou...

Our local government has leased the rights to build solar panels over their parking lots to a private sector company. They've covered most lots at this time.

The panels have all of the advantages outlined in the article.

The only downside not mentioned was snow and ice falling from the overhead panels. At least one person has been hurt.

Putting solar panels in the road/parking-lot = bad idea. But putting them over seems like a good idea from my limited knowledge.

Yeah, the problem with the hype for solar roadways is that this alternative exists. Even if it were a good idea (which it isn't), this would beat it every time in terms of maintenance, energy efficiency and cost. And frankly additional benefits, shade is better than LEDs.

So even if the economics works, and it doesn't, it wouldn't make sense to start with solar roadways until the carparks are all done like this, and that's a long long way away.

You are not factoring in the added savings on asphalt. Asphalt roads are expensive. For example, the new I-4 expansion in Orlando will cost $2.3 billion for 21 miles of 4 added lanes. The reason solar roadways make economical sense is because it replaces the road itself and thus adsorbs the cost of the asphalt that would otherwise have to be used. Solar canopies only make sense for parking lots and only in hot regions.

That $2.3 billion figure is for a lot more than the road surface.

But aren't solar panels vastly more expensive than mere asphalt, per unit of area?

Why yes they are. You need more than just solar panels though. You'll need thick tempered glass, power inverters, monitoring and management systems, transformers and high voltage power lines. Once installed, your glass blocks will provide the ride comfort, noise, safety, of brick or cobblestone roads but less durable and more slippery.

I seem to remember that cobblestone roads were almost as slippery as ice whenever it rained. I grew up in a town that actually had cobblestone streets (long story, Europe).

You almost certainly still need a concrete or asphalt road bed under the panels, no?

Yes. The asphalt is probably the cheapest line-item in the $2.3B budget. Not sure what OP is on about..

If there are any materials you could choose to use that are vastly more expensive than asphalt, glass and solar panels are right up high on the list. The price of a solar roadway would be staggeringly higher than a regular one. (Currently, most of the cost of roads is labour, earthworks, concrete piling, steel structures, etc.).

But solar roadways are ridiculous for another reason - first, putting a solar panel under a thick layer of glass will lower its efficiency greatly - because the thickness of the glass will reduce light transmissibility through it, making the panel far less efficient than a regular one on a roof etc... Secondly, the glass is really slippery, and the only way to fix that is by texturing it or coating it in something, both which will reduce transmissibility even more. Next, if you've ever dropped an ice-cream on the road and the picked it up again, you'll know that roads are ridiculously dirty. The dirt and grime will build up, just like regular roads, reducing the efficiency even more. Then, the cars driving over it will grind that dust into the glass, and any abarasive material will put tiny scratches in the panel - which over time will build up and again reduce efficiency further.

Dave Jones from the Electronics Engineering Video Blog (EEVBlog) did some calculations in one of his videos - assuming optimal efficiency. Even then, a panel would not make enough electricity to pay itself back (can't remember the time period exactly - over 20 or 30 years? Or perhaps it was the estimated lifetime of a panel).

But with all these extra losses, there is no way it would ever work without huge advances in solar technology and materials science.

You are 100% correct, but it begs an addition:

Industrial-scale rural solar power would beat this every time in the same metrics. Land isn't a scarce element of solar power - and transmission is cheap.

This seems to be a much better option than setting up large solar farms in the middle of the CA desert. Parking lots are eyesores anyway so cover them up with solar panels. Why ruin pristine nature with solar panels.

The difference is the deserts get serious insolation. Or put another way, the places with major sunshine do not also contain major cities. Another problem with cities is the structures shade the panels.

Depends on the cities... here in the Phoenix area most of the buildings are only 1-2 stories.. and most of the larger parking lots don't get any shade from the buildings... There are several of these covered lots here in Phoenix, and more going up. A lot of places have covered parking anyway, so throwing solar panels on them isn't that much more cost in labor, and payoff in 8-12 years usually, with some profites for 5-15 after (at least from the costs of the past decade as a forcast).

There's hardly any 'desert' near major cities with skyscrapers. Maybe LA but still nothing like NY. IMO putting serious money into solar panels anywhere other than sun belt of US is waste of money.

A major Midwest software company near me has these over their visitor lot (their employee lot being underground), and has a huge farm of solar panels behind the building. I think it's a great idea.

On the graph at the bottom, does anyone know why the estimation goes down after 2016, then only slightly rises in 2018? There has to be some reason why solar installs would take a major hit like that, but I didn't see it explained in the article.

The source of the chart data is linked just above it.

GTM Research forecasts that the market will continue to grow year-over-year until the drop-off in the federal ITC, peaking at 318 megawatts in 2016

The federal ITC is a tax credit.

> Asphalt and concrete absorb the sun’s energy, retaining heat — and contributing to the “urban heat island effect,” in which cities are hotter than the surrounding areas.

If the solar cells were coated with some layer that reflects all the photons that can't be harvested for electricity that might mitigate that problem even further

Or maybe they already are?

- All heat not reflected is absorbed.

- Solar panels operate more efficiently at lower temperatures. [1]

Based on these facts, I'd venture to guess that your idea is already being worked on.

[1] http://homeguides.sfgate.com/effects-temperature-solar-panel...

most are black because that's what absorbs photons. asphalt happens to be black, but it converts 100% of captured energy into heat, whereas PV systems decrease that value to 95-50% (source: http://en.wikipedia.org/wiki/Solar_cell_efficiency#mediaview...)

They're black in visible light. But as far as I know they cannot harvest IR photons. So it would probably be useful if they reflected IR.

Although I don't know if it's better for them to be reflective or black in the IR window where where atmosphere is transparent. Black makes for good emitters too and that way they could shed heat into space.

If we could arbitrarily designed reflectivity vs. transparency it would probably be transparent in visible, reflective in IR, black in the IR window

Despite all the positives - not everybody is a fan of these. This is a battle being waged in Connecticut over solar carports:

http://www.fairfieldcitizenonline.com/news/article/Neighbors...

That sounds more like someone is sour over their own zoning permit being denied than any actual opposition to the panels themselves.

I think the panels might block the road visibility of his business (which I don't have a lot of sympathy for, but it's at least a less petty motivation).

I sure hope such investments have enough time to make their money back. I expect robotic cars to do away with the need to own personal cars. Shared by many people, a robotic cab will spend a lot less time sitting around and many parking lots will disappear.

This strikes me as the perfect political investment. It passes the "new one on me" test, and it passes the "green is hip" test, and it would be a constant reminder of the politicians involved (ala Boris Bikes for Londoners).

It also promises to kick start a maintenance industry and lower costs as stnadrds are formed.

Overall I would expect this one to be subsidised and persued more hungrily than any offshore projects or windfarms

In Europe and Asia, I'd expect so. In the States, fossil fuel interests have already mobilized their media campaign, pushing for new taxes to penalize local solar energy generation. They've had some victories and some losses, but as another poster mentioned, they don't have to win every battle - just enough to sow uncertainty on whether it'll be a good investment.

Our local high school (bay area) has solar panels over the parking lot. Seems to be working out.

This is nice but this is also 99.99% of solar related energy "solutions".

If we put <some solar tech> in <some place> we could generate enough energy to power <many things>; however it is still not cost-effective to do so.

Yeah right... this is not true at all.

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