I connected them to my solar panels (with pre-installed connectors) and the charge controller and. Nothing! At first I thought my solar panel crimps/connectors didn't need to be compatible with the supplied connectors, so I cut the old connectors off my panels and replaced them with the supplied connector set. Connected the. Nothing! I took my multimeter and checked for continuity and found the wires were fine. Finally I took the great crimps I just cut from my boards, removed the pre-installed crimps from those wires and replaced them with my old connectors which worked and I finally had a connection! Two stars because the cables were ok, but whoever installed the preinstalled plugs didn't do me any favors. It would be better if the wires came unplugged, that would save me from unnecessarily removing good plugs from my panels.