Solar film - could it help power a vehicle?

[rmay635703]

Originally Posted by Christ

If you're out at night, the car is still sitting outside in the driveway during the day, in most cases... wouldn't it have the same effect? Just a thought...

good argument pro-cell though.

I'd love to see that link, so I know I'm not remembering things that aren't really there.

PS did you really mean "inefficient" up there? I would wonder why they would want to make something "inefficient" is why I ask.

Usually if they are like me and the car is at home it is being charged off the wall so the solar on the car would be moot at home.

Yes I did mean inefficient, the goal was to make it as cheap as regular paint, efficiency was a distant 2nd so there would be absolutely no reason not to impliment because the price would be the same as regular paint.

[Ryland]

I was thinking about this the other day, in relation to keeping your car charged and warm, as the batteries are under more strain in cold weather and mirrors with trackers are cheap and mounting PV on something like a flat roof is not a good use as they don't get full sun and in the winter it's even less so, but if you reflected the light to the PV and used that waste heat that is created to keep the engine of the car warm on a gas car, or the cabin of the car on an EV then it turns in to a win win with solar charging and solar heating of your vehicle, in the summer the light is more intense so that extra power could be used to run a fan to cool the car.

[Christ]

You mean by placing the PV inside the car (EV example) and allowing the mirrors to track the sun so there is always a direct light source on the PV, and the heat from the light going through the window heating the inside of the car?

Could you sketch an example layout?

[Ryland]

Originally Posted by Christ

You mean by placing the PV inside the car (EV example) and allowing the mirrors to track the sun so there is always a direct light source on the PV, and the heat from the light going through the window heating the inside of the car?

Could you sketch an example layout?

that would work in the winter, but not so well in the summer, no, my idea is to have a heat exchanger on the back side of the panel and have it on the roof, in the summer that heat would be piped to the radiator to keep the pv cooler, in the winter it would go right to the engine block to keep the engine warmer, electricity would keep the battery toped off, this would work because only 15-20% of the energy in light is turned in to electricity in a PV, most of what is left is heat, some of it bounces off of course (more the case if the PV was behind the windshild).

[Christ]

Originally Posted by Ryland

that would work in the winter, but not so well in the summer, no, my idea is to have a heat exchanger on the back side of the panel and have it on the roof, in the summer that heat would be piped to the radiator to keep the pv cooler, in the winter it would go right to the engine block to keep the engine warmer, electricity would keep the battery toped off, this would work because only 15-20% of the energy in light is turned in to electricity in a PV, most of what is left is heat, some of it bounces off of course (more the case if the PV was behind the windshild).

Question about PV cells... can a PV be made that any light will actually get through?

IF so, could those PV's be stacked so that the light passing through the first has to pass into the second one, scavenging more of the light's energy?

Obviously, the first one would be inefficient as compared to normal PV's, since it wouldn't be able to capture as much light energy being opaque, but the second layer could be a standard efficiency, which reflects light...

Using a one-way mirror effect, with the impermeable side facing the non-opaque PV cell, would that not allow for concentration of heat, that could then be vented/directed to any where you could put ducting?

What I'm thinking is kinda like this:

-----------------------------------------|
~~~~~~~~~~~~~~~~~~~~~~~~~~|
~~~~~~~~~~~~~~~~~~~~~~~~~~|
================================|

Legend:
----- - opaque-one way mirror PV
~~~~ - airspace
===== - Non-opaque PV
| - wall/cap

See what I'm saying? As the light passes through the upper layer of opaque photovoltaic cell membrane, it produces SOME electricity, maybe enough just enough to power vent fans.

It then reflects off the second PV, back to the first one, which has a "light comes in but don't go out" mirror effect (like the interrogation rooms at the cop shop), which would reflect the light energy back to the primary (non-opaque) PV.

The result of having the clear-ish membrane is, of course, a greenhouse effect, which would cause heat buildup, which could then be vented (after passing a wind-vane type setup, for reclamation of energy) into whatever area you could duct heat to.

Now, if it isn't obvious by now, I know almost nothing about PV cells. I just like to think that I can ask the right question to get someone who does know to think in a different way...

So if this sparks your million dollar idea, just give me credit somewhere, and we're cool. :P

[theunchosen]

When you think PV think a little over 3 watts per square foot. 1 KW =1.15 HP(ish).

Using the PV to add to your distance on EV is not worth it until Solar cells go from their current 19-20% efficiency to something like 50-60%.

I'm pro-PV though. If you are an 8-5er then your car can sit at work all day and charge. So. . .Let's assume your work is 30 miles. at 30 miles the Aptera would be right at the point it has to kick on its ICE to recharge batts. But. . .you had your car sitting outside all day and it was sunny half the time so. . .(My car can fit roughly 5 BP375's (12 square feet 3x4)) so thats 5*75 watts*4.5(the BP 375 produces 75 KW an hour of sunlight five of them and 4 and a half hours)= 1.687 KW. . or 2HP/hour. basically enough to keep your EV only mode on until you get home without the ICE kicking in.

Also. . .If you don't go to work it can charge for free at home. . .Not that its terribly expensive but its 10cents per KWH that you don't have to pay. . .

I would leave it unplugged during the day to afford the most juice from the panels and then plug it up at night(assuming you aren't going anywhere for a couple of hours.

As previous replies state it would also boost you a few miles while you drive(assuming you go 30 you might get 33)

[theunchosen]

Originally Posted by Christ

Question about PV cells... can a PV be made that any light will actually get through?

No.
Sorry.
PV works. . .because the photons that make up light "happen" to strike the electrons in the waifer as they pass through. The semi-conductor has an electron sharing quality that allows them to be popped out of orbit easily enough that a passing photon that happens to occupy the same space at the same time can bounce them out of orbit. The photon then passes the rest of teh way through the first membrane and strike the second and is absorbed as heat, or in the case it did not strike an electron in layer 1 it may still have enough energy to pop an electron loose in layer 2. PV is difficult because you are relying on the probability that a photon will strike an electron.

Of course we can improve our odds(originally PV produced far less like only 1% of the time did a photon bounce an electron out of orbit opposed to the 20% we see now) by using things that are better semi-conductors and allow for a more. . .evenly(?) distributed electron field to improve our chances of a collision. Thats what the big race in PV is. Find a semi-conductor compound that distributes electrons in a fashion that they are out there and get a "hit" 50% of the time. . .or actually just 25% of the time per layer for a total of 50%. . .different materials for different wavelengths of light otherwise it just sails right past.(Blue and Green are the most common forms of light in our solar system thats why they are blue and green(also why plants are green)).

[order99]

I'm curious-I know that the PV 'trickle charge' is pretty useful in extending battery life for Lead Acid, but does it help any for NiCad, NiMH or the Lithium families? Or do you just get the extra mile or so of performance?

[Christ]

Thats' a good question, I never really thought to ask... I second it.

[Thalass]

I like this idea. This way not only would the window tinting keep the car cooler by limiting the sunlight getting in, but it'd use some of that sunlight to power vent fans and further cool (or heat, I suppose) the car. Nice!