Featured Toyota testing new solar powered Prius

This brings up the point that cantilevered mechanized solar panels are
“quite expensive “

The point that panels on a car are more than on a roof of a house is true but the devices pictured over parking spots are an order of magnitude more expensive than the panels mounted to them.

 

Expensive cantilevered single-pole mounts are by no means mandatory for that approach, that is simply an example I have personally seen during my travels. Most any ordinary solid carport or shade structure will do.

 

Doesn't Windex have a product for cleaning exterior windows that just attaches to a hose?

If you only consider them has PV holders, and ignore the other benefits, which are the same ones as any covered parking spot.
Another important consideration is that they don't need to be cantilevered. The ones I've seen aren't, so the structure cost should be about the same as a car port for a home owner. I'm guessing cantilever was chosen for the panels in that photo because it was cheaper to install than tearing up pavement and repaving the lot.

Specific sites will vary, but I think it will help overall with snow. The installation I saw wouldn't interfere with plowing the lot. In some cases, it might be possible to arrange the panels so shoveling and plowing takes less effort. A portion of the snow falling on the panels will melt before getting to the ground. Then less snow falling on cars means less digging needed to get them out, with less of the accompanying idling of them.

 

the local high school - maybe 4 blocks down the road put several of these bad boys up.

You might say they are dual cantilevered because you have panels hanging off both sides of the single main structural poles. It seems like it wouldn't be any more expensive to have a single pole, rather than mounting poles on both sides, one side being shorter, the other side taller. Either way - the tilt allows for better drainage as well as sun capture. A single pole means high school kids have 50% less chance of smacking into them.

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Where there’s strong demand for electricity plus shade and zero demand for solo-operator snowplowing, that looks like a good fit.

 

In snow country, just leave the snow along the pole line. Cars aren't suppose to be driving through that space to begin with.

 

I think if you want it to last 30+ years it is less expensive to have poles 4 poles holding corners, plus perhaps some additional structural poles if the top is too heavy. Then these don't need to be as strong. 4 poles for 30 years is a lot cheaper than 4 tires as those tires will never last that long and must be changed. I believe your photo had 3 poles in left, right, and center of the structure. This saves 1 pole, but really the poles and attachment have to be stronger for similar longevity, still 3 is not much different than 4.

Its probably an accetic thing. our local schools got retrofitted with geothermal hvac which has saved a great deal on air conditioning costs. Still not as much is spent on local education, and schools here could run on wind ;-)

 

Unfortunately if you are thinking of these we use them for trim:


But we use two of these to get rid of the snow in our parking lot:


South facing "solar canopies" wouldn't cut it because if they were angled in the winter toward the south, there would be almost no protection because our snow generally comes from the West, North and Northwest. We have a north wall and parking lot egress is west and east for 800 of my co-workers. So guess where the snow goes?

 

Shopping centers may use the latter here. Mounting the panels higher is always an option, and so is simply building a covered parking structure.

Of course, in areas with such snow conditions, PV mounted on cars isn't going to fare any better. The angling of fixed PV panels means the snow slides off as it melts, so power generation can continue at some pace without intervention. Generally not the case for cars in heavy snow.

 

We use this

 

That would not be PV friendly.

The one I've seen parked behind a store during the winter uses iron oxide instead of paint to protect its surfaces. Its age is probaly measured in decades.

The snow and ice melt off the PV panel. Like the slate roof of my garage. The only snow possibly left past morning after a snow fall is in the shadow of the lower north side. Otherwise there is a bank formed from where the frozen water slid off. Other buildings with slate install 'feet' to keep the snow on where its falling off could hurt someone.

The panels are designed to absorb the sun's energy, so little is reflected away. Then only 20 to 30 percent is being converted to electricity, which leaves a lot of energy to become heat. On top of that, the PV cells produce heat as they work. So a tiny bit exposed starts heating up in the sun, and heat spreads though out the panel.

Even when nothing is exposed, the melting of the top layer trickles down to the panel, where it becomes a lubricant on the slick surface of the panel, and works with the slope to slide the snow or ice off. Don't forget, fixed panels should be facing the sun, so shade spared snow shouldn't be an issue.

The horizontal surfaces of a car generally aren't conductive to letting snow or ice slide off under its own weight. In my experience, if the snow is left on the car, the melt collects in the bottom layer and refreezes at night, becoming more difficult to remove. Properly installed fixed panels will clear themselves, while ones on a car roof require you to clear them. Which, judging by the cars around here, isn't going to happen.

 

Yes, winter is the pits for solar energy, due much more to severe overcast cloudcover than to snow and ice in my climate zone.

But that is why I installed enough solar capacity on the house to make up the winter shortfall during spring, summer, and fall, to get to net-zero on an annualized basis.

The people who declare that solar doesn't work because of our nasty winters, should have told me so before I went and actually did it. It is too late now that I have first-hand experience to show otherwise.

Yes, I still need to be tied to the grid. But solar power seasons and hydropower seasons are somewhat complementary, so they work together reasonably well.

 

There are quite a few tricks to keep snow off of roofs, especially in & near rain gutters & lower roof pitch extremities where ice dams form. Here's the type that we use;



The dialogue here got me to wondering what would be the trade-off, if one were to have a more extensive system during harsh winters ... weather one were using recirculated warm water on the back side of panels - or heating elements like ours. Appliances like these could make them duel dual-purpose, instead of just for preventing ice dams.

 

I'm assuming you say this in jest...but have you ever been thru a Minnesota winter? The 'pole line' would turn out to be the entire parking lot by the end of the winter.

 

There are also roof rakes that let a person clear off snow from the ground.

When I worry about ice dams, I make snow balls mixed with salt or fertilizer, and toss them up there.

When the parking lot here is plowed, the actual spaces are cleared by the plow going across them. Only the end spaces are cleared by the plow driving into them.

So the plow drives parallel to the poles, leaving a thin wall of snow between the the poles. That is easy to knock down and clear, but it really doesn't need to be. It also isn't a big deal to have the poles far enough apart to let a plow that can fit under the panels between them.

The panels should reduce the total amount of snow that is on the pavement under them. A portion of the snow that falls on them will melt before reaching the ground. The rest will collect in a pile along the lower edge of the panels, which can be away from the poles. If wind driven snow is more common, perhaps install some fencing or hedges for a wind break.

 

Well back to the topic....

If they could put a small one of these on every hybrid, it would help with running the HVAC, or even ventilation like the old Prius IV solar roof. Heck even if it would help with the defrost or maybe a heated windshield. Double the battery, with half being a buffer for the solar roof, then it could be used for topping off the traction and 12v battery, as well as HVAC. This would definitely speed up falling costs of these exotic materials (GaAs triple junction thin film solar cells) through mass production.

It is easier to amortize the cost through another cost vehicle than to try and create a market for an extraordinarly expensive product on it’s own.


iPad ? Pro

 

Ok mr. expert... However, I can guarantee you the plow drivers would F'n hate it. And that is also why you never see anything like this in MN....It just wouldn't work well.

 

Pssst, using the term "never" in your arguments typically ends poorly.
Stop by the Great River Energy headquarters in Maple Grove. You will see that setup.
Done with care and forethought, it can work well.
Certainly not in all situations, but definitely in some.

 

Seeing how plow drivers purposely try to remove speed bumps and bury cars, why should we care about how they feel?
Yeah, it will add some effort to plowing than a flat expanse of tarmac, but so do median strips and sidewalks.

As for why you haven't seen such parking lot panels in in, well, maybe you just haven't traveled around enough. The MSP airport also has them. MSP airport ready for the sun with new solar array – Finance & Commerce
Or maybe PV is getting installed onto existing structures first. MN and NJ both have strong solar incentives. In my travels through NJ, I've seen one parking lot install; a new school, I think(area hit by Sandy). I've seen more square footage of panels attached to utility poles, before we get to counting roofs.
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Which is basically how the current PV system on the Prime works. For $3000 using cheaper cells, it is a tough sell for US buyers.