Re: IOG and EV charging with Solar/Battery installation
Posted: Mon Mar 09, 2026 9:38 am
So, my theory in practice...
Recap:
The problem I have is that the EV charger is wired to the CU, so the Fox hybrid inverter sees this as just another load. It then tries to supply power (a max of 3.6kW for my pathetic car) when Octopus tells it to turn on. This drains the Fox batteries.
Solutions:
Suggested solutions are to add another (smaller) CU just for the EV and tap this off the tails before the inverter's CT.
Or, to add another CT placed on the EV cable and wire this in reverse back to the inverter.
My suggestion:
Disconnect the EV live cable from the RCBO in the CU. Add a (sufficiently thick) single core from this RCBO and through the CT clamp in the reverse direction, then connect this cable back to the EV charger. Effectively, just adding a longer live wire from the RCBO through the CT clamp to the charger.
Results:
Normal operation for the inverter when the EV was not taking power.
I initiated a bump charge from the Octopus app and, after a short delay, my IHD popped up saying 3.6kW. The Fox app reported no change to normal operation and was supplying power to the rest of the house.
Conclusion:
I have no reason to suspect that this is not a workable fix for anyone in the same position. The cost of fixing is one electrician to do it properly, and about 1 metre of thick cable. Thoughts?
I should mention that if you are competent, then a 6mm2 WAGO and a metre of 6mm2 brown conduit cable, plus a little trunking is all you need.
Recap:
The problem I have is that the EV charger is wired to the CU, so the Fox hybrid inverter sees this as just another load. It then tries to supply power (a max of 3.6kW for my pathetic car) when Octopus tells it to turn on. This drains the Fox batteries.
Solutions:
Suggested solutions are to add another (smaller) CU just for the EV and tap this off the tails before the inverter's CT.
Or, to add another CT placed on the EV cable and wire this in reverse back to the inverter.
My suggestion:
Disconnect the EV live cable from the RCBO in the CU. Add a (sufficiently thick) single core from this RCBO and through the CT clamp in the reverse direction, then connect this cable back to the EV charger. Effectively, just adding a longer live wire from the RCBO through the CT clamp to the charger.
Results:
Normal operation for the inverter when the EV was not taking power.
I initiated a bump charge from the Octopus app and, after a short delay, my IHD popped up saying 3.6kW. The Fox app reported no change to normal operation and was supplying power to the rest of the house.
Conclusion:
I have no reason to suspect that this is not a workable fix for anyone in the same position. The cost of fixing is one electrician to do it properly, and about 1 metre of thick cable. Thoughts?
I should mention that if you are competent, then a 6mm2 WAGO and a metre of 6mm2 brown conduit cable, plus a little trunking is all you need.
