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Solar panels - Series or Parallel wiring

September 05, 2020, 01:58:49 pm

Found a good explanation about wiring solar panels series or parallel with regard to partial shading:

Conclusion last paragraph from:  Wiring Shaded Solar Panels | altE Solar Blog

"So, this kind of shows you, that if you do have some partial shading, and it's on only one of the panels at a time, so say you've got a chimney that you really have no control over, or if it's on a sailboat, and you've got the mast that is kind of important, if you've got partial shading that's going to be changing, it's better to wire them in parallel to give the parallel path for the non-shaded panel. Ideally, and I know I say this a lot, ideally each panel should have its own charge controller, that way you will get absolute maximum performance, but if it's not an option, wiring in parallel with partial shading is your better solution."

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Re: Solar panels - Series or Parallel wiring

Reply #1 – September 05, 2020, 02:19:59 pm

All 7 of mine are in parallel as we only dry camp and there are always trees in the sierra campgrounds. One or more will be shaded at all times of the day. Four on one controller and three on another.

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Re: Solar panels - Series or Parallel wiring

Reply #2 – September 05, 2020, 05:50:34 pm

We also only dry camp and with four 36 volt panels, we have a parallel/series wiring and bring 72 volts in four wires down to a bus right behind the controller. Even with trees around, we are at float by noon. 1140 watt potential with just over 400 Ah batteries. RV propane fridge. Working well going on twelve years now with no changes.

Maximum wiring loss on any system should not be over 3 percent from panels to batteries.

Pierce

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Re: Solar panels - Series or Parallel wiring

Reply #3 – September 05, 2020, 06:48:52 pm

We have four 300 watt panels all in parallel. Everything I read says parallel wiring is the most tolerant of partial shade.  We just finished 7 days dry camping in the Tetons. Every night but two was in the 30s.  The other two were upper 20s.  One day (in between the cold nights) got to 45°, heavy clouds all day and rain most of the day.  We have a residential refrig, 600 amp hrs of LiFePO4 batteries.  Most the other days were partly shaded in the afternoon. We averaged about 4Kw production each day except fot the rainy day. We started the week at 100% SOC and ended at 76%. 

We have been here before in sites with zero shade and produced more than 5Kw.  Without the afternoon shade we would have been back to 100% SOC.  I have room for two more panels, time to start shopping.

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