Ground wire size for a 340 Watt panel on a metal roof

[adriansantos]

Hi,

1. Wanted to ask for help for an off grid system im building. Am hooking a 340 watt Poly panel to my 24v system. Want to get your advise on what is the the accepted ground wire size ( Panel is about 4 meters away from the ground).

2. And another thing i would like to ask, if the panel has been installed on a metal roof that is sits on metal beam/post to the ground (with rebars), do you still need to install a separate ground wire?

3. anyone had some electrocution from a panel here? just asking

Thanks

 

[gnubie]

Q 1 and 2 are going to come down to the regulations in your area. Best advice. Check your local regulations or at least state where you are in case someone on the forum knows the answer for your area.

Here the requirement is 4 sqmm. The framing can be used but it needs to be properly earthed itself and the panels / racking / framing must be joined in such a way that won't corrode. Panel to racking is using those little crush plates with the bits that dig into the aluminium etc.

The worst I've ever heard of happening here has been people getting leakage tingle from capacitive coupling. This is normally only an issue with high frequency inverters. There was one person posting on the forum that claimed to have received a quite a jolt if he got between the panels and the earth. I don't think he ever posted the resolution of the problem... hopefully nothing nasty happened.

 

[adriansantos]

Q 1 and 2 are going to come down to the regulations in your area. Best advice. Check your local regulations or at least state where you are in case someone on the forum knows the answer for your area.

Here the requirement is 4 sqmm. The framing can be used but it needs to be properly earthed itself and the panels / racking / framing must be joined in such a way that won't corrode. Panel to racking is using those little crush plates with the bits that dig into the aluminium etc.

The worst I've ever heard of happening here has been people getting leakage tingle from capacitive coupling. This is normally only an issue with high frequency inverters. There was one person posting on the forum that claimed to have received a quite a jolt if he got between the panels and the earth. I don't think he ever posted the resolution of the problem... hopefully nothing nasty happened.

Thanks for the input!

Am located in the Philippines and we really dont have any clear regulation on the grounding requirements. Was able to buy the 3.5sqmm, the 4sqmm is not available locally, the next size is 5.5sqmm.

Wont be using any inverter in my system, just purely the 24v converted to 12v to run some pond pump and air pump and some lights at night.
Thanks again!

 

[gnubie]

So it's more for lightning protection? If it's under 32V there's no shock hazard unless someone starts sucking on the wiring.

 

[adriansantos]

So it's more for lightning protection? If it's under 32V there's no shock hazard unless someone starts sucking on the wiring.

Just trying to copy how everyone do their grounding. We dont have any lightning strikes in our city.