Roof color for solar panel

[sxharr05]

I'm considering adding a small solar panel to the top of my truck's cap to act as a sort of a trickle charger for a second battery I'll be adding for small accessories. I'll be painting the topper shortly and was wondering if there is any benefit to a black or white roof. I know about the reflective properties of a lighter color vs the absorption of darker. But is one better suited for the function of a panel than the other? For what it's worth, the topper will be painted dark blue and I'll do the roof accordingly.

 

[dwh]

Doesn't matter. There are some special panels that can absorb light on both sides, but they're not very common and anyway, one wouldn't install those in a flat mounted configuration. Tilted panels can put out quite a bit of extra power on a snowfield, due to reflected light, but it wouldn't make any difference for a little trickle charge panel.

Solar panels get hot all on their own since they are dark color and pointed at the sun. For that reason, it's normally best to install them with an air gap underneath for cooling. Again, not a big deal on a small panel.

An extra benefit of the air gap on a vehicle install, is that it keeps the sun from hitting that part of the roof directly so it keeps the roof a bit cooler. Again, not significant with a small panel.

 

[sxharr05]

I figured as much, based on the small panel I'd be using. Just thought I'd ask to be on the safe side. Thank you for a very thorough reply.

 

[taugust]

I would recommend the lighter color. Solar panels loose efficiency when they get hot, so keeping yours as cool as possible is best.

 

[yaknowthatguy]

have to agree with taugust - color does have an effect. curiously enough, on a small panel with limited output anyway, it may be more pronounced.

Consider taking a look at the manufacturer's heat/voltage curves. Often around 115-120F panels take a big dive in efficiency, even if in full sunlight. the air gap prevoiusly mentioned will be a big help, but reducing heat around the panel is important to maintain overall output efficiently. This is why solar applications aren't quite perfect for the southwestern desert (ironically).