Insulation level of a photovoltaic system is low. Therefore，lightning protection design of photovoltaic systems is targeted for lightning-induced voltages as well as shielding effect of lightning rods. Photovoltaic generation is expected to play all important role to cut the peak electric power in summer，and number of photovoltaic panels rapidly increases. Lightning damages caused by direct lightning hit to photovoltaic system might clearly appear due to the increase of the panels. In this paper，an experiment of discharge between a rod which represents a final jump of a lightning stroke and a photovoltaic panel is carried out. The experiment shows a surface discharge occurs after a sparkover between the rod and the panel when a flame of the panel is grounded，and damage in the panel rarely occurs due to the surface discharge.