Solar combiner box questions
I'm looking for a solar panel combiner box for the RV's roof. I'm going to start with 2 panels with the option to add 2 more if needed. I've seen some that are stupid expensive and some that aren'...
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I've got my system set up with 10 X 100 watt panels on the roof, all wired in parallel in two 500 watt banks. Used a gray plastic combiner box on the roof, group of waterproof strain reliefs. Inside two fuse blocks combining off the panels into two 500 watt banks, two buss bars for neg wires. 6awg wiring from each fuse block to the two Bogart SC2030 controllers in the front compartment of the 5er. SC2030's are regulated by a trimetric. I spray painted the combiner box with white liquid rubber to protect from UV. System works great at handling the assorted partial shading I almost always encounter in the areas we like to camp. Of course the twin full height AC units, vents, TV antenna etc all tend to contribute to shading of some of the panels at certain times of the day as well, especially in the winter months.
With the panels you're looking at, you're going to have to use an Mppt controller, which don't do well in my experience with parallel panel strings when encountering shading. The way the bypass diodes work on the panels, they are basically panel strings even if you only have two panels in parallel, and with the mppt controller you'll loose pretty much the entire output of a parallel string that is partially shaded. None of the mppt controllers I played with seemed to be able to figure out a good setpoint under conditions where the parallel strings didn't balance out fairly well. I'd recommend a series configuration if you're going mppt, or a separate controller for each string.
With the panels you're looking at, you're going to have to use an Mppt controller, which don't do well in my experience with parallel panel strings when encountering shading. The way the bypass diodes work on the panels, they are basically panel strings even if you only have two panels in parallel, and with the mppt controller you'll loose pretty much the entire output of a parallel string that is partially shaded. None of the mppt controllers I played with seemed to be able to figure out a good setpoint under conditions where the parallel strings didn't balance out fairly well. I'd recommend a series configuration if you're going mppt, or a separate controller for each string.
