Solar on the hood?

[Wandererr]

I currently have a 160W solar panel which I use to recharge my second battery that runs the fridge in my jeep. The panel is folding style which I deploy when parked for any length of time. The upside of it is that I can place the panel out in the sun. Downside is that it's not secured and at times I just don't feel like putting it out there because sometimes it makes it impractical.

The roof on my vehicle will be covered up by a cargo container and a roof basket. This leaves me with the hood, but that leaves me with a few questions: will the heat from engine affect negatively the flexible panels? Any issues that I should think about?

Btw this would be going on a Jeep Wrangler.

[SunEagle]

Short answer is yes the engine heat may hurt the output of the panel.

[J.P.M.]

I'd guess engine heat may be a problem, but less so than one might think. I'd be more concerned about what something on the hood did to the driver's field of vision.

I do know the former chief of research at what was Harrison Radiator (The subsidiary of GM that made all their heat transfer products) They had some serious research facilities with ovens that held multiple vehicles that were used for testing. But I don't know if the hoods were instrumented. I kind of doubt if anyone has measured the hood temp. of a moving vehicle. When I go to Death Valley in July every year, it's common to see heavily instrumented test vehicles for new models blasting over the desert and at the gas stations or the crews holed up at Furnace Creek Ranch.

I don't know if anyone has measured the hood temp. of a moving vehicle, but when the vehicle is moving, air will circulate behind/under the panels at ~ the vehicle velocity +/- a bit. That'll keep the hood and the panels cooler. When stationary, the hood will begin to cool off and in any case probably won't be much, if any warmer/hotter than a roof the panels might have been sitting on in any stationary application.

My wife owner an unkillable Jeep Cherokee for 18 yrs. and I don't remember the hood being excessively warm when garaged after a trip, but that's anecdotal. I do seem to remember the under hood insulation being rather thick.

[Wandererr]

Regarding vision: it seems that the flex panels are less reflective then a clean hood. The damn thing is like a mirror at times. So from the perspective of glare I think I'm good.

Regarding the heat - I didn't think about the cooling effect while driving. The issue though is if I have to idle and not move..... Is the heat effect that you're thinking off one that causes damage to the panel or is it that with raised temp the panel efficiency drops down and when they cool back to normal they go back to normal?

[SunEagle]

I wasn't thinking of driving with the panel on the hood of the engine compartment. Yes the wind rushing over it will cool it but another issue is that when the panel is laying flat then it may only produce it's full charging amps for a short time when the sun is directly over head. That will cut down on the daily charge rate and may be nothing more than a trickle charger for the battery.

While a trickle charge will keep a battery up it will hardly be able to replace a deep discharge that your loads will put on it during the day.

[Wandererr]

Yes - I'm aware that the hood panel will be limited in production to when the sun hits it at the proper angle, but the panel would be there for when I'm doing sight seeing during the day. Stopping for lunch, etc. I will still deploy the folding big panel when appropriate.

[Mike90250]

While you are driving, the engine alternator will produce much more power in an hour, than your panel would in several days. I see no way to justify a panel on the hood to charge battery while you stop driving for an hour to eat lunch. Maybe while parked for a couple days, it would be worthwhile