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I am looking for help as my knowledge of solar charging (and apparently physics) is limited.

I have a solar charger that plugs into the 12 V socket in the car. It's intended placement is on the dashboard (although I do consider placing it on the roof and threading the cable the sunroof). My car has a heat reflecting windscreen (I believe it's a metallizing layer laminated in the glass), which I presume would reflect IR light.

Would this also reduce the energy generated by the charger, compared to a conventional windscreen?

Voltage Spike
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user1018551
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  • Most likely it will reduce the usable light that hits the panel, yes. But I would still prefer to keep the panel inside the car rather than run a cable through. Personally. It is just so much more protected inside the car. – user57037 Apr 29 '21 at 16:49
  • Protected eg from the elements, or theft/vandalism? The plan was to use it on shorter stops in safe-ish places, plus no glass in the way should really improve output – user1018551 Apr 29 '21 at 18:05
  • Protected from the elements is what I was thinking. You are in a much better position than me to assess the theft/vandalism situation since it is your vehicle. ;-) – user57037 Apr 29 '21 at 18:42
  • It seems like it would not be terribly difficult to try it both ways. Let it sit long enough to come up to temp, then measure the charge current. Then move it and try it again. Besides incident light, panel temperature is the next important factor in determining power output of a panel. I suppose the panel will be hotter inside the vehicle with zero convection. But both places will be pretty hot. Heat reduces power output. – user57037 Apr 29 '21 at 18:45
  • Yep, I thought the IR reflective windscreen might help with the heat issue, but it would still be affecting it. I plan to use it on nicer days, so hopefully elements won't be a problem, but need to consider cost/benefit of having the panel out instead of just in the car behind front/side/rear (but heating wires) windows – user1018551 Apr 29 '21 at 19:45
  • Try both locations and see what happens. Even if you can't measure power output, you can just measure the temperature of the solar panel itself. Whichever location keeps the panel cooler will probably work better. The light filtering effect is probably smaller than the temperature effect. – user57037 Apr 29 '21 at 23:48
  • The roof of the car will likely be extremely hot. It may be hotter than the dashboard location. Hard to say. But the panel will be spaced slighly above the roof and have access to wind, if any. On the dash, there will be no wind. So I really don't know which location will be hotter. JUST TRY IT OUT. Don't agonize over it. It will probably work well enough in either location. – user57037 Apr 29 '21 at 23:50

1 Answers1

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Generally speaking, solar cells harness visible light for energy and do not make use of other parts of the electromagnetic spectrum (such as UV or IR).

As mkeith points out, the power generation could still be reduced depending on how much near IR light the cells can make use of and how much visible light is reflected by the windscreen.

Aaron
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  • They do use near IR. And it is very likely that the coating in the windscreen absorbs or reflects some visible light, too. – user57037 Apr 29 '21 at 16:50
  • @mkeith good point, I will edit my answer – Aaron Apr 29 '21 at 17:23
  • I couldn't find concrete data on light throughput difference between IR control and normal glass, but I presume it's out there – user1018551 Apr 29 '21 at 18:16
  • @user1018551 Corning (as in Corningware) makes different types of windows tintings, they may have data available. – Aaron Apr 29 '21 at 19:52