[chbot] solar roads

[Charles Manning]

I pretty much agree with Geoffrey

While flat panel PV is now getting to around the $1/W mark and is getting
viable for more and more applications, trying to PV a road throws up a
bunch more challenges.

Engineering is the Art of Compromise. Whenever you have to take on new
operational parameters you need to give something else away. PV is hard
enough to make work on rooftops, let alone on the road.

A few points Geoffrey did not raise:
* These need to be rugged. That means thicker materials. That means
expensive and lower light penetration, therefore lower efficency.
* The ideas they put forth here are strange: (eg. Sidewalks covered in the
stuff, shaded by cherry trees.)
* Roads are dirty places.
* Roads and parking lots are busier when the sun shines. That reduces their
efficiency by a healthy factor.

Looks like a scam site really, gathering funding for something that has a
lot of "buzz" but is low in utility.

PV is fine for a few % of power, but really has little or no potential to
be a major (greater than 20%) contributor to power. As long as people want
power at night, there will need to be more mainstream generation. That
means the mainstream plants need to be built. Large thermal plants like to
maintain steady loads - to be efficient anyway - and putting PV on the grid
messes with that.




On Mon, May 26, 2014 at 6:49 AM, Geoff <sdfgeoff at gmail.com> wrote:

> It's a bad idea.
>
> This project has popped up on quite a few sites that I frequent, and I've
> answered similarly to all of them:
>  - The energy used to manufacture them and install them is very very close
> to the amount you get out of them over their operating life
> For a normal solar panel, it's energy payback time is about 7-8 years, a
> third of it's life. For a solar road compared to a normal panel:
>  - Shorter cell life (Wear and tear from driving)
>  - Lower cell efficiency (because it's flat, and scratches)
>  - Higher manufacturing energy costs (as it needs to be stronger to
> counter the first point)
>  - Higher installation energy costs (as there can't be seams, and existing
> roads must be pulled up)
> Using some approximations I figured that solar roads would have only a
> slight energy saving compared to just using fuel (Energy Payback was 11-13
> years of a 15 year life). Put in terms of money, it's not worth it.
>
> So I doubt we'll see them anytime soon. Maybe when fuel goes up in price.
>
> Geoffrey
>
>
> On Sun, May 25, 2014 at 11:15 PM, Peter Ellens <ellensp at gmail.com> wrote:
>
>> Hi.
>>
>> Off topic, but interesting.
>>
>> You guys that know a lot about solar, what do you think of these solar
>> roads ideas
>> https://www.indiegogo.com/projects/solar-roadways#home
>>
>>
>>
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