single or more panels

[wls]

I was doing some thinking, say you have a 200 watt panel, and puts out 8 amp, in great sun (just a number I came up with). Amps I assume is what charges your batteries. So you go with the thought, more is better, put another 8 amp solar panel and run it in series, short run to your controller etc. So you double your volts, which may work with your controller better, but still charging the battery with 8 amps. Same panels, but run parallel, so the volts stay the same but amps double to 16. Doesn't it make sense to run parallel as much as possible, no shade, and running 10 gauge wire. just wondering. I will keep this to just 2 panels. I'm sure there are probably 100's of reason, more is bigger. Oh ya, I'm not talking about the 1000+ panels you see in a farmers field, but stationary, for like a RV, or RV roof top. Thanks

 

[miataroadster]

It depends on what type of fridge you have: absorption (ac/dc/propane) or compressor (dc only).

If you have the the first one, you probably won't need a solar panel at all. At least, that was my experience. Just make sure you have a good battery, preferably LiFePO4 due to a lower cost now than years ago. Okay, If need be, yeah, one solar panel and a good mppt charge controller would be nice additions.

If you have the power hog 12vdc fridge, you definitely need a 200ah battery and at least 400 watts of solar power and a good mppt charge controller.

The above is base on boondocking.

IF you'd like to splurge- buy an inverter or portable inverter generator to have120v available or alternator/solar DC charger to charge your battery or batteries.

Lastly, you could also buy a solar generator/powerstation(ex, Ecoflow, Oupes, Pecron, etc) so you have 120 VAC and 12vDC to power common rv appliances(coffee brewer or toaster or electruc grill) and to charge phones, use CPAP machine.

Yeah, I went overboard with having a backup for another backup. Lol.

Have fun with your DIY rv project!

 

[GolfingDave]

I am going to go with the parallel crowd. You can not always be in full sun and from what I have read parallel is better for shaded areas. With that in mind I then figure it works best in lower sun days(winter) too.

10 gauge wire on a camper, I do not think you have to be concerned about excessive voltage drop so the extra voltage is not really required.

Numbers are not too far off. I think the best I have seen is 23 amps with 600 watts of solar wired in parallel in an open field. Maybe some day I will be sure to check at full sun on a clear day.

Maybe the better informed here and can chime in on this? It kind of is along the same lines.
3 panels in parallel on my roof slope two on one side.
What would be the benefit of adding a 4th panel and wiring it in series with a panel on the opposite slope and keeping the same 30 amp 10 gauge wiring I have. Not wanting to go in parallel and have to upgrade the wiring. No plans on doing it but just something I have wondered about also.

 

[TitanMike]

I was doing some thinking, say you have a 200 watt panel, and puts out 8 amp, in great sun (just a number I came up with). Amps I assume is what charges your batteries. So you go with the thought, more is better, put another 8 amp solar panel and run it in series, short run to your controller etc. So you double your volts, which may work with your controller better, but still charging the battery with 8 amps. Same panels, but run parallel, so the volts stay the same but amps double to 16. Doesn't it make sense to run parallel as much as possible, no shade, and running 10 gauge wire. just wondering. I will keep this to just 2 panels. I'm sure there are probably 100's of reason, more is bigger. Oh ya, I'm not talking about the 1000+ panels you see in a farmers field, but stationary, for like a RV, or RV roof top. Thanks

Remember that a 200 watt panel delivering 8 amps ( your number) will produce different numbers at the output of the solar charge controller. The output from an MPPT charge controller will be more like 14 amps at ~14 volts.

A single 200w (RV type) panel will only deliver ~18-22 volts. Two 100 w panels in series, 36-44 volts which is very beneficial when using an MPPT controller.

Remember, Watts into a solar charge controller and watts out into batteries is what you should look at, not just volts or amps separately.

Lastly, shade is shade. If you're parked in trees solar is handicapped, period. If that's your preferred style, consider portable panels.

As an alternative CIGS panels have many more bypass diodes into their construction so partial shade doesn't have as drastic an effect on panel output as ordinary panels with only two bypass diodes. The CIGS panels are more expensive but they also do more.