THE BEST SIDE OF SOLAR PANEL HAMNESS MANUFACTURER

Along with the growing variety of apps for PV technology, there was a necessity for a safe and easy-to-use solar panel connector, This can be when MC3 solar connectors had been produced. this is the dumb query but I’m not solar panel savvy. What do the rubber plugs at the end of solar panels do? Are they needed? I have 3 that are missing and I