Ground mount (galvanised poles) solar array - do I need an earthing rod?

[Bramco]

Hi,

 

Just about to mount the PV panels on a ground mount which consists of 16 metre long galvanised poles hammered into the ground with the structure attached above.  A very similar arrangement to the one @billt showed in @ProDave's post from 2018 

 

 

The question is, given the amount of steel in the ground, do I need an earth rod?

 

Simon 

[ProDave]

Driven in like piles?  I would say no, by comparison that will be a better earth than any little rod would be.

[Bramco]

13 minutes ago, ProDave said:

Driven in like piles?

Yes.

 

And thanks for the quick response.

 

Simon

[Dillsue]

9 hours ago, Bramco said:

The question is, given the amount of steel in the ground, do I need an earth rod?

That's a question for whoever's signing off your install as they know what and how things have been installed. But....

 

As I understand things if its just panels and their DC cabling on the mounting frame with the inverter and AC being elsewhere, then any earthing is pointless as the DC from the panels isn't referenced to earth. This means that there isnt a fault path to earth so having any earthing provision isnt going to do anything to clear a fault.

 

Take professional qualified advice to be sure, as thats not what Im offering.

 

Watch you dont fall off the steps when hammering the poles in!!

[Bramco]

13 hours ago, Dillsue said:

That's a question for whoever's signing off your install as they know what and how things have been installed.

 

It's a diy install, hence the question.

 

13 hours ago, Dillsue said:

As I understand things if its just panels and their DC cabling on the mounting frame with the inverter and AC being elsewhere, then any earthing is pointless as the DC from the panels isn't referenced to earth. This means that there isnt a fault path to earth so having any earthing provision isnt going to do anything to clear a fault.

 

From the panel spec sheets, the frames need to be earthed.  So it's really this aspect and they are connected very firmly to the frame which is mounted on the poles in the ground.

 

13 hours ago, Dillsue said:

Watch you dont fall off the steps when hammering the poles in!!

 

They're only a metre long, so no ladders needed but I did slip one of the builders a few quid for him to wield his massive sledgehammer.  Think as a pensioner, I'd have managed a couple a day....  He had it done in 15 minutes - he did look knackered towards the end!

 

Simon

[dpmiller]

Is the earthing then for galvanic or lightning protection?

[Bramco]

30 minutes ago, dpmiller said:

Is the earthing then for galvanic or lightning protection?

 

Lightning protection.

 

Simon

[Dillsue]

3 hours ago, Bramco said:

 

Lightning protection.

Is the array high up or particularly exposed? No experience with lightning protection but believe you need pretty chunky cable from each exposed conductive part to earth so could end up spending more on cable and earth rods than a blown module, which is unlikely to take a strike unless it's on top of a hill or tall building.

[Dillsue]

4 hours ago, Bramco said:

They're only a metre long, so no ladders needed

Ah, it was the 16 metre poles I was concerned about!!!

[Bramco]

29 minutes ago, Dillsue said:

Is the array high up or particularly exposed?

 

Not exposed at all - and there's a couple of big ash trees not too far away to the north.

 

27 minutes ago, Dillsue said:

Ah, it was the 16 metre poles I was concerned about!!!

 

But if we'd balanced the array on a 16m pole, then it would be a little more exposed - but I'd be questioning what to do about stability in a gale...   😄

 

Simon