Just another question on Solar

CA Traveler wrote:
einstein,

The typical modern panel has bypass diodes so shading is a non issue. RVers with smaller arrays than yours would be better served with fuses vs a 0.5V drop diode since the typical solar controller provides night time blocking.

I agree on small systems like 2 or 4 panels in parallel the bypass diodes will suffice.

When you increase the voltage by series is when you start to go beyond the bypass diodes' rated power. Therefore, adding an additional diode rated for the full string will isolate each string of panels from the others.

Diodes not only help with shading but also helps with: improper installation, isolates manufacturers' defects, and isolates damaged panels from the others.

Example (more like a what if):

Two panel system in parallel: One panel is damage and water sets in and shorts out internal wires. The damaged panel acts like a load and draws from the other panel which will burn out if not protected.

If you isolate with a diode the power will never divert to the short and you get at least half of the power to your controller. If you use fuses the fuse pops on both panels and no power goes through. Diodes are as cheap as fuses now days.

Note: circuit breakers can be reset, but after it trips/pops, it is recommended to be replaced according to the manufacture. Just a tidbit :-).

Edit: Fuse works if you want to know if something is wrong. Diode works if you just want outputs no matter what.