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I wonder how they will hold up to big trucks.
They should have no trouble holding up to big truck... They have been load tested for 230,000+ pounds.

SolarRoadways said:
How much weight can these panels support? Semi-trucks get pretty heavy!

Originally, we were designing toward 80,000 pounds. That was supposed to be the maximum legal limit for a semi-truck. However, we live in logging country and a former logging truck driver informed us that they don't have scales in the woods and that he'd topped out at 124,000 pounds. So we decided that we should go for 150,000 pounds. We then learned that oil companies can get permission to move refinery equipment up to 230,000 pounds on frozen roads, so we decided to shoot for 250,000 pounds.

Both 3D Finite Element Method analysis and actual load testing at civil engineering labs showed that our Solar Road Panels can handle that and more.
 

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Discussion Starter #5
I wondered how well they'd hold up to snow plow trucks with chains .....


I'd love to have those things on my driveway and sidewalks. Beats the heck out of traditional paver blocks.
 

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I hate to pop a bubble here, but as nice as this solar electric idea sounds, it's not practical. It appears that the cost per watt seems to drop to about 1/2 every 10 - 20 years (it varies). The price per watt has come down a lot, but it's not low enough to get a reasonable pay-back period.

Solar Power's Massive Price Drop (Graph) | CleanTechnica

Forecast: Cost Of PV Panels To Drop To $0.36 Per Watt By 2017 | ThinkProgress

If you just look at the cost of panels, you're missing most of the story. There's installation costs, conversion/storage costs, and other things.

Putting the panels on the road increases the cost of the panels, increases the installation costs, increases the maintenance costs, and so on. It would be far cheaper and wiser to put them as shade above parking lots.

Another factor is that the angle of a panel should face the sun. Laying flat is the second worst choice to make, the amount of sunlight is reduced. Using Los Angeles as the the example, a panel sitting at 0 degrees would see an average of 4.9 kWh/M^2 per day. Tip the panel to latitude and the number jumps to 5.6 kWh/M^2 per day. Laying flat, you're losing 12.5% of the energy, but it gets worse as we move north.

http://rredc.nrel.gov/solar/pubs/redbook/PDFs/CA.PDF

See any Map: Solar Radiation Data Manual for Flat-Plate and Concentrating Collectors

In Spokane Washington, the numbers would be: 3.8 kWh/M^2 per day vs. 4.5 kWh/M^2 per day. That's a loss of 15.6%.

http://rredc.nrel.gov/solar/pubs/redbook/PDFs/WA.PDF


Another factor you have to consider is that a road picks up more dirt and crud than a panel off the road. Any dirt, crud, or pain applied to the road reduces the efficiency of the panel. The drawing shows panels with paint on them, that's NOT a good idea, because the paint blocks the light.


Bob Diaz
 

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The drawing shows panels with paint on them, that's NOT a good idea, because the paint blocks the light.
Actually, the drawing shows panels lighting up the strip under them, not paint. Many of the items you noted were covered in the article and on the site. You may want to actually read the info instead of glancing at the pictures...

There are still issues to resolve, that's true. And this may not be the optimal use for this technology. But they've seemed to have come up with some rather inventive and useful ideas. Even if it's not applied here, it may find use elsewhere.
 

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Impractical idea, why not just make a solar farm.

Also, most asphalt roadways come from recycled/repurposed materials versus manufactured solar cells.
 

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The following video shows why this is impractical:

https://www.youtube.com/watch?v=H901KdXgHs4


Bob Diaz
And, they've already responded....

I love the non-factual facts, like "glass is a pretty soft material compared to asphalt". Doesn't exactly inspire you to believe most of the rest of the "debunking" facts used.

Again, not saying this is fool-proof, or even great for what they're touting it for. Personally, I see this happening more for personal drive ways, airport runways, and/or parking lots at apartment complexes or other parking complexes which are often empty during the day (movie theaters, for example).
 

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One big problem from my POV is this country's disinterest in maintaining, let alone upgrading infrastructure. It costs money, tax money. So long as Congress is only interested in reducing taxes for the 1%, with no interest in falling bridges and such ... this proposal doesn't have a chance. Technological barriers or no.
 

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And, they've already responded....

I love the non-factual facts, like "glass is a pretty soft material compared to asphalt". Doesn't exactly inspire you to believe most of the rest of the "debunking" facts used.

Again, not saying this is fool-proof, or even great for what they're touting it for. Personally, I see this happening more for personal drive ways, airport runways, and/or parking lots at apartment complexes or other parking complexes which are often empty during the day (movie theaters, for example).
Look I understand, they are telling people something they want to hear, but let me point out that the arguments against this happening are far stronger than the arguments for it happening. Consider their point, "False Claim: we can't afford to heat roads", while he quotes a number of issues, he does not address how this is even possible.

The standard for solar is to assume that we get 1kW per square meter at maximum sunlight. However this condition does not exist anywhere on Earth. At best we're a bit under that amount, but the number is the standard we use for calculations.

In an ideal solar system, the panel must be facing the sun, not flat on the ground. According to the US Government's Data on solar radiation, a panel at zero degrees (flat on the ground) in Portland, in December, should get around 0.7 --> 1.3 kWh/M^2/day or 1kW/M^2/day average. Assuming you have every square inch of your 1 square meter covered, that comes to 1,550 square inches. Take 175 watts for 1 hour / 1,550 square inches and you have 0.11 watts per square inch for 1 hour to melt snow. In simple terms, it's not going to happen.

http://rredc.nrel.gov/solar/pubs/redbook/PDFs/OR.PDF

Now cover that same panel with say 3" of snow and the power level will drop considerably. Why is it that black asphalt, which had a higher efficiency of turning sunlight into heat than solar, can't melt a layer of 3" of snow during the winter? If you understand this, you'll start to see that their claims are foolish. For Portland, it would cost far less to put the panels beside the road and turn them to face the sun at 45.6 degrees, not 0 degrees, but even this is not enough power to melt snow and ice.


There's a saying, if it's too good to be true, likely it isn't.



Bob Diaz
 

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You may want to read what I wrote when replying.

In an ideal solar system, the panel must be facing the sun, not flat on the ground.
No one is claiming these are ideal collectors. Non-motorized collectors in general are not ideal, but tons of homes have them installed and are getting great benefit from them. This is about using the *space* more efficiently, not about doing the most efficient thing.

Would road-side panels be better for highways? Probably, assuming you have space on the side of every road to put these. Not all roads have that.

As I said above, it's probably not suited for what they're claiming. But that doesn't mean it's not useful for some things. It's like saying "Eating pasta with this rake is less efficient than using a fork... We should not have rakes." Rakes have advantages in different forums, just as these could have advantages in some areas.

Take 175 watts for 1 hour / 1,550 square inches and you have 0.11 watts per square inch for 1 hour to melt snow. In simple terms, it's not going to happen.
Now cover that same panel with say 3" of snow and the power level will drop considerably.
Yes, if you calculate it based on what it takes to melt a block of ice, which is what most people are using for this argument. The problem is they're not talking about 3" of snow or ice. They're talking about keeping the surface just warm enough to prevent the snow from collecting in the first place. Those are different numbers. It takes significantly more energy to melt a large block of ice than it does if you break up that block into 20,000 small chunks.

And yes, asphalt does that quite well, but it's also rather expensive to maintain. Would this be less expensive to maintain? I have no idea, but now they have the funding to start a small test bed. If it works, great. If not, then we learn from that. Would you rather have them spend the money on lobbyists to force this tech into laws the way ethanol did?
 
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