PV-panels and Lightning
Putting solarpanels on the roof doesn’t really change the chance of a lightning strike. Lightning usually strikes on the highest point and on a slope roof that will never be the solar panels. On a flat roof the solar panels might be the highest point, so in that case so precautions might be needed.
To “protect” the solar power installation, it is of importance that we try to prevent a “coil” in the solar panel wiring. If lighning strikes nearby, it creates an electro-magnetic field. A coil acts like a transformer. If panels are connect in series then it is easy to make an induction loop like that.
This “ring” is sensitive to a electro-magnetic field that is created by high voltage discharge that is caused by lightning. The coil works as a transformer and generates a high voltage on the PV-wiring. This spike might damage the whole solar installation.
To just use some extra cable that is kept close to the other conducter we highly reduce the induction area and there for lowering the risk of damaging anything when lightning strikes nearby.
Besides wiring in the right way it might be good to add an surge arrester in the solar installation. The arresters are available for both Direct Current as well as Alternate Current. Every DC-string should have it’s own surge arrester.