I had a sparky out to quote me on tying my inverter into my DB box. He included installation of an earthing stake @ >R1800-00. He says the batteries have to be grounded close by. The thing is, the batteries are in my garage. I said I’ll do it myself. I started to drill a hole close to the wall which naturally
hit the foundation. I had a very long drill bit - about 700mm - and still couldn’t get through - which is when the bit snapped in the hole…
That let me to wonder, how effective would a spike be when a large part of it would be surrounded by concrete? If the answer is, not very, then I’d have to move the spike far enough away so that I don’t hit the foundation. That’ll leave it well into the garage, probably 500mm or so. Having a spike sticking out of the floor is obviously not an option so I’d have to put it below the floor level, chase a slot to the wall and cover it back up after the spike and earth cable are installed. Not an ideal solution.
Is all this really necessary in order to get a COC?
Does your house already have an earth? As far as I understand, you need a single earth for the house. Isnt there already an earth bar on or near your inverter?
I had another electrician here just now. He confirmed that an earth stake is not necessary, since the inverter is earthed to the house earth and the batteries are earthed to the inverter. Which makes sense to me.
Everything is earthed to one equipotential point, namely the earth provided by the supplier. If there is a path (of some sort, even if a fault condition is required to make that path available) from the grid supply to the PV panels, then the PV panels must be earthed to the same earth.
Batteries are not earthed, unless the inverter maker tells you to.
Just to confirm. That means that the PV panels can be earthed to the supplier’s earth such as the earth used by the house from City Power in my case. No earth spike needed.
If you don’t currently have an earth spike I would still install one, and bond it to the earth from the council, just in case something goes wrong with the supplied earth. The more earth spikes the merrier.
Just make sure you do the bonding outside your house, so that if lightning strikes the ground and generates a potential difference between the various earth spikes that the bulk of the current does not flow through your DB board.
I installed a separate earth spike for my PV panels and bonded it to my existing earth spike. If my roof gets struck by lightning it might just save some of the equipment in the house.
My Pylontech 2000C is earthed to the one earth point in my AC connector box, which goes to house earth. Victron Inverter. @JacoDeJongh assisted with installation, so I assumed I’m right in this.
Should I be concerned?
EDIT:
In trying to do research and asking on forums about earthing I quickly learnt, as Jaco suggested I would, that people stay away from the topic, seems an arcane magic almost
When you say “earthed”, you mean the earth stud on the outside of the case? That should be earthed, yes.
Sometimes people mean “the negative pole on the battery” should be bonded to DB earth / earth spike / etc. That is potentially (!) needed, but ONLY IF your inverter installation manual says so.
In almost all fixed-installation cases the negative pole should NOT be earthed.
Any metal enclosure that forms part of the greater installation should be earthed / bonded to the DB earth.
Indeed, but you most certainly don’t need to drill a hole through the floor and install your own spike! I think that was the more important thing that had to be said.
For lightning protection you would want a low impedance path to ground which implies an earth electrode as close as possible to the array.
This earth electrode should be bonded to your AC earth electrode to ensure an equipotential voltage between your earth electrodes during fault conditions.
If you don’t bond the earth electrodes and you have a potential difference between them due to lightning, you may have an unintended current path through the interconnecting cabling.
