Protecting your solar investment from lightning is not as complex as one may think. It is also not as simple as just grounding the solar panels. Lightning can damage your solar system in one of two ways; the first is the most common and involves a nearby indirect lightning strike inducing transient voltage (a surge) into your solar systems panel’s or electrical wiring. The other source of damage would be from a direct strike or side flash to the solar array itself which can cause physical damage to the panel or panel’s themselves as well and send excessive voltage into the system.
The only effective way to protect a solar system from the damaging effects of lightning is a 2 step approach.
Step 1: Install a traditional lightning protection system on the structure in which the solar array is located within the zone of protection protecting it from a direct strike and with proper bonding protecting it from a side flash.
Step 2: Install surge protection on the electrical panel and between the PV array and inverters, batteries and other controls or monitoring equipment which may be employed into the system.
A good read is the linked bulletin from UL: Lightning Protection for Solar Panels Protects Your Investment
Lightning Rod Systems For Residential, Commercial and Equestrian Structures