Solar PV rooftop systems: Lightining protection
As all solar generators are mounted outdoors, they are exposed to lightning-current-induced power surges. To protect the modules and wiring against such surges, the clearance between (a) module areas that are electriﬁed by the module wiring and (b) lighting rods and down-conductors should be as small as possible. Moreover, suitable surge diverters (varistors, if possible either sufﬁciently oversized or equipped with thermal monitoring devices for ageing induced leakage current increases) should be integrated into the solar generator junction boxes (in relatively close proximity to the modules)
between the positive and negative conductor and ground.