Solar panel on the bonnet

Derekoak

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I have a microcamper based on a doblo xl. It has 160 w semi flexible solar on the roof. That is ok in summer without driving for our use but with lower sun we must drive every day. The only large space left is the bonnet, due to a midi skylight. I think I could fit a 120w semiflexible on the bonnet, with a rear connection box cut into the bonnet, curved for and aft to the bonnet and fitted on strips of fore and aft putty, sides with stixall, that would allow some back ventilation. This is how the roof panels have been fitted.
I have never seen this done. Is there a problem that I cannot forsee? Heat from the engine greater than Spanish summer sun?
 
Maybe a portable folding panel would be an easier option for more solar, though may still not meet your winter requirements.
 
Heat would kill it and sticking anything onto paint is madness, apart from the fact stick down panels are not as good as rigid and have a shorter life, folding stand alone panel would be best, make sure you are using a mppt regulator, and maybe add an extra battery if you can find room.
 
Yes you can never have enough solar in some conditions, even thinking like "The Martian" .
I prefer to be self contained, to just drive away. Portable panels are not my first option, but thanks
 
I like that, as well as the bonnet one. We unroll an insulated black blind to cover the windscreen inside when parked in sun ,usually facing south. we could add a solar panel to that somehow. We would are already doing that so adding it would be less bother.
Still any opinions on the bonnet position?
 
Derekoak said:
I like that, as well as the bonnet one. We unroll an insulated black blind to cover the windscreen inside when parked in sun ,usually facing south. we could add a solar panel to that somehow. We would are already doing that so adding it would be less bother.
Still any opinions on the bonnet position?
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Heat from the engine, increasing the bonnet temperature :unsure:
 
Bonnet sounds OK it'd wouldn't be facing the sun every where you stopped don't think heat would be a problem as when driving the air passing would keep it cool and keeping the sun off the bonnet would help cool the engine a little. Where ever you put it it could be stolen or damaged a portable one would need to be stored when not in use and you don't have a large van
 
I can see the attraction of a 'fit and forget' panel over a folder.
As others have posted sunlight reflecting off it might be a problem, I would be very wary of doing it due to this.
As for the heat, running the beads of adhesive front to rear so air can channel under whilst on the move should help, just make sure it is well held down so it doesn't get lifted by air pressure, my old semi flexible had bolt holes in each corner.
 
Derekoak said:
I have a microcamper based on a doblo xl. It has 160 w semi flexible solar on the roof. That is ok in summer without driving for our use but with lower sun we must drive every day. The only large space left is the bonnet, due to a midi skylight. I think I could fit a 120w semiflexible on the bonnet, with a rear connection box cut into the bonnet, curved for and aft to the bonnet and fitted on strips of fore and aft putty, sides with stixall, that would allow some back ventilation. This is how the roof panels have been fitted.
I have never seen this done. Is there a problem that I cannot forsee? Heat from the engine greater than Spanish summer sun?
Click to expand...
I like the idea even with the potential problems. But semiflexible panels generally don't like being flexed in two opposing directions. I don't see heat being a problem as long as the underside of your bonnet is insulated. Air gaps under semiflexible panels is silly, you need the panel at an even temperature to prevent micro cracking. I think what you would need is a CIGS type panel that is adhesive backed. Expensive and limited in the range of sizes. As mentioned it will be directional and in view of tampers. But then if someone is going to mess with your van they'll do it any ways. Don't forget you'll need another mppt controller to get the best out of it. Personally I'd be looking at hanging another panel on the side.
 
trevskoda said:
Heat would kill it and sticking anything onto paint is madness, apart from the fact stick down panels are not as good as rigid and have a shorter life, folding stand alone panel would be best, make sure you are using a mppt regulator, and maybe add an extra battery if you can find room.
Click to expand...
I've been using flexible panels for years without problems, you just need to fit them right and just like the "heavier" rigid ones you only get what you pay for although a "budget" rigid one is easier to change when it goes belly up. Buy quality stuff and fit it right no matter your preference. My current ones consistently give near enough their rated watts in the summer months and the weight saving helps with the all important payload when you're fulltime. ;)
Screenshot taken on 22/06/2020 while running the fridge off the inverter just to try it, 4 x 150 watt flexible panels, the next day I ordered a fifth panel and fitted it after moving the Snipe over to make room for it :)

2020_06_22 Solar_with_fridge_on.jpg


Kind regards,
Del
 
I am not an expert but if you lift the bonnet, Fiat have seen fit to install a plastic engine cover? Under and over this is fan ventilated. I cannot imagine, thinking about it, that engine heat can be worse than solar on my black car? I will carry out an experiment drive a good distance in full sun stop and feel the bonnet compared to other external car surfaces.
I think the figured (dimpled) plastic top cover of the panel is less reflective than the bonnet paint. I think that plastic would cope with a stone thrown by a vehicle better than my windscreen?.
Little fingers would not harm themselves poking, as all the wires would be under the bonnet. I was not quick to see what big fingers were but yes theft is a little more likely except they will not get semi flexible off in a useable condition quickly. My 160watt of semiflexibles on the roof have lasted 3 years with no problem. You can flex a semi flexible as a gentle cylinder or a gentle cone, not 2 ways at once. My bonnet is nearly only curved fore and aft, if I only use the middle metre. Any difference the other way is taken up with butyl putty strips of different thicknesses. Bolting the leading edge, (and trailing edge) down to stop aerodynamic lift and make theft harder is worth doing.
I think butyl putty and black stixall have stood the test of time. I do not know of more heat resistant spacer/glues. I would really struggle to get a failed panel off if stixall was used other than on edges, where a knife can reach?
I have a problem with an over used battery after 3.5 years, but a larger lithium battery should solve it and give an effective 25% increase in solar area, due to better charging efficiency. If that is not enough I may add more solar, my preference is the bonnet.
I like the light from the midi skylight so dont want to cover it. I might get a 50 watt thin panel alongside the skylight raised to top of skylight height to avoid shading but that is more difficult than the bonnet, or the moveable panel inside the windscreen, so that is my least best option.
 
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