Solar Electric Vehicles

My calculations and experience show that you need a *minimum* 5 Watt-sized the solar panel in order to get any charging to your battery (and even then, it's a very s-s-l-l-o-o-w-w charge)... This takes into account average daylight hours, the parasitic drain of the vehicle's electronics, and also the loss through the windshield glass.. Anything smaller than 5W is just a waste of time and money..

I don't think UV is a big loss for solar panels; the very glass they are made from blocks most UV, so the additional layer of car glass isn't going to make much more difference in that regard.. Where you do lose is on the IR side because windshield glass (in particular the Toyota glass) typically contains iron in the formula which blocks a lot of the IR light frequencies.. The old crystalline panels are least affected by this because they tend to have a peak response in the visible light region and are also still the most efficient solar technology, although they are expensive.. The newer amorphous panels are less efficient but have more of a response in the IR region, so they take a greater hit sitting behind windsheld glass.. Because of this, small amorphous panels sold as "car battery maintainers" are really nothing more than a scam because they lose so much of their already small efficiency that the best that they can do is slightly delay the ultimate demise of your 12V battery.. Amorphous panels are best purchased in large panels with lots of surface area and set up in arrays on your house where you can take advantage of the large area and low initial cost of the amorphous panels..

 

<div class='quotetop'>QUOTE(c4 @ May 27 2007, 07:10 PM) [snapback]450827[/snapback]</div>

Yeah, I was a bit hasty in my reply. I should have just said that the glass filters much of the light energy (and this includes UV, IR and even visible since they are mildly "tinted" as well). I've tried the test (and should do it again) with a small PV panel. Holding it in the direct sun, and then behind a windshield makes a significant difference in output. It will also likely get hotter being inside the car which will derate the output even more.

 

<div class='quotetop'>QUOTE(daniel @ May 27 2007, 09:52 PM) [snapback]450901[/snapback]</div>

I'll go with the subtle addition:

"The most logical *production* gasoline-burning car on the planet."

 

<div class='quotetop'>QUOTE(daniel @ Apr 17 2007, 03:31 PM) [snapback]424802[/snapback]</div>

I think the ideal situation is to have PV panels on BOTH the car and garage. When the car is in the garage (in shade), the car still charges. When sitting out in a parking lot, it is topping off. End result, best of both worlds.

 

<div class='quotetop'>QUOTE(GadgetMan2 @ Jun 3 2007, 03:38 AM) [snapback]454307[/snapback]</div>

Well... no - as has been mentioned. It is a very energy-intensive and expensive proposition to put panels on a car if they will only be used to a small fraction of their potential. The panels on the roof of your house are collecting power at all times, when it is available. The ones on your car are being wasted much of the time. Eventually it would be great to have them cheap and simple enough to use them in such a "disposable" way. But certainly not today. Would you really pay $5,000 for the chance to *possibly* harvest about one mile of extra range in a day? Your net pollution footprint would likely go up when you compare the gasoline-burning savings to the energy input needed to make that under-used PV panel.