mcgivor ✭✭✭✭✭✭

Each module should have its own protection to prevent backfeeding from the other modules in the event of a short in an individual, a DC circuit breaker like this https://www.amazon.com/Low-voltage-Mi…

So 6 sq.mm? Dose each module have its own protection, typically ~15A fuse or circuit breaker? 

What size do you have and how long is the run? Going by your signature the modules are in parallel, do each have overcurrent protection before the combination point?

The purpose of the fuse is to protect the conductors, therefore the gauge, or cross sectional area, is required to determine tha appropriate fuse capacity.

They are diodes, used to bypass shaded cell strings within the module, this allow partial output rather than no output. They are very cheap, I would replace them, the panel will operate with them byp…