Earthing of Solar Panels and Rails (what is required?)


I’ve installed galvanised Roof Hooks and Rails on my Garage Roof, now going to mount 8 x Jinko PVs and would like to find out what is required in terms of earthing the PVs and Rails.

Do I have to earth both (PVs as well as Rails) separately to the ground? Or can the earth wires be combined (PVs to Rails and Rails then earthed to the building wall or into the ground) and does the thickness of the earth wires make a difference?

I can understand that it would protect against electrical faults and short-circuit etc. but for a lightning strike even a thick earth wire would probably mean nothing :slightly_smiling_face:


You need to earth your panels.
I’ve read that the earth needs to be routed directly to an earth spike (but that was some time back on another forum :slight_smile: )
If its a IBR roof then make sure this is earthed as well…
As far as lightning is concerned if your garage isn’t the highest point of your house then it has a better chance of survival in the unlikely event of a strike.
But remember that lightning arrestors don’t divert a strike: Their function is to ionize the air around the arrestor thus preventing the likelihood of a strike (citation needed)
PS: But above all ensure your system is covered by your bondholders insurance!

This is a general overview: Dehn PV Rooftop Protection

Lightning Protection/Earthing guide
A Great guide you can download


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Thanks Sarel for the comprehensive Manual, but wow, there’s a lot of granular detail and specific info there that goes way over my head.

In layman’s terms I am trying to establish what would be the minimum requirement for earthing one’s Solar Panels. It is only 8 x 470w Panels (for now), in series, mounted to 2 x galvanised steel rails using galvanised steel roof hooks and and galvanised steel clamps (all 8 panels in 1 row).

Would it be adequate to run a 16sq mm naked earth cable from the one end of the string to the other end and having it attached with earth clamps to each panel’s frame and then from there it runs down the side of the building and earthed into the ground with a copper-plated earth spike, or can it also be attached to the building structure (thick steel pipes in roof that is earthed to the walls and ground at many places) + let it run to the earth wires of the Sub-DB box in the garage (in other works earth it to as many places going to the earth as possible, not only to the earth spike)?

Even a 16sq mm earth wire would probably only earth against electric faults on the panels themselves (the string will only carry 11.5 amps at peak sun due to being wired in series) but with a lightning strike not even an earth wire the thickness of one’s arm would survive, so I am guessing we are required to earth the PV array for electrical reasons and not for lightning, correct?

I do have the other equipment in place (Isolator + fuses + over-voltage protectors) in the DC Distribution Box where the Solarflex Cables goes to first (and from there go into the Inverter).

Thanks a lot.

We normally use 6 mm. In large installations we use 10. The galvanize rails complicates your situation. Galvanic corrosion will cause you loosing earthing properties between the rails and panels over time so your best option will be to install earth calmps/clips on each panel and connecting the earth directly to the panels. With Alu panels on Alu rails you can just earth the rails and it will be sufficient.