Is it ok to have PV system into shared (household) RCD?

jez234 · Oct 12, 2022

Is it ok to have PV system into shared (household) RCD?

So I've had a system installed, but not yet complete/signed off. The issue is that the PV (and a car charger) are wired into a shared RCD (with water heater, boiler and downstairs sockets). When all breakers are on, the system trips. It works when either sockets or PV system are off.

From what i have seen (from my light research), it generally bad practice to be putting the PV (and presumably EV charger) into a shared RCD. Secondly, if it were to be in a shared RCD, then it should be a type B.

Issue is that there isn't space to put anything more into the fuse box, so would require another external box. It may be possible to free up a space if I can replace the door bell transformer with a single size unit.

Inverter: solaxpower.com/x1-boost/

Battery: alphaess.com/smile-b3-plus-3kw-residential-energy-storage-system

Charger: myenergi.com/product/zappi-ev-charger/

westward10 · Oct 12, 2022

No it isn't okay because if the rcd trips it can feed back into the other circuits.

jez234 · Oct 12, 2022

westward10 said:
No it isn't okay because if the rcd trips it can feed back into the other circuits.

Ok thanks - whats the best course of action? Do I need a whole additional fuse-board to accommodate the additional RCD? And does the charger need its own RCD or can it share with the PV?

westward10 · Oct 12, 2022

Can you show a picture of your consumer unit.

jez234 · Oct 12, 2022

westward10 said:
Can you show a picture of your consumer unit.

Here! The 2 on the left are the new additions. The car charger was freed up by putting the downstairs lighting in with the upstairs on the other RCD. Thanks

[ElectriciansForums.net] Is it ok to have PV system into shared (household) RCD?

westward10 · Oct 12, 2022

What is FB2?
That 50A circuit breaker for the above is not compatible with that consumer unit.
They really shouldn't have put all your lighting on one circuit breaker.

jez234 · Oct 12, 2022

westward10 said:
What is FB2?
That 50A circuit breaker for the above is not compatible with that consumer unit.

That's the solar stuff. No idea why it's called that. What makes it incompatible? Would that explain why it's tripping?

westward10 · Oct 12, 2022

jez234 said:
That's the solar stuff. No idea why it's called that. What makes it incompatible? Would that explain why it's tripping?

It should be a Hager device not Steeple, FB2 would probably mean Fuse Board 2 but that isn't causing the tripping. Tripping could be an excess of leakage from the combined circuits or a fault.

loz2754 · Oct 12, 2022

The Code of Practice for EV charging states that "Every charging point shall be individually protected by an RCD...."
Page 53.
In other words, not by an RCD that also protects other circuits.

jez234 · Oct 12, 2022

westward10 said:
It should be a Hager device not Steeple, FB2 would probably mean Fuse Board 2 but that isn't causing the tripping. Tripping could be an excess of leakage from the combined circuits or a fault.

That's what he's been saying - that existing socket circuit had too much leakage and the PV system in addition is too much.
But you are saying it's unsafe and doesn't meet the regulations to be on the same circuit? I want to have a clear plan of what I need to ask for.
I think there needs to be an additional fuse board with an RCD each for the PV and charger? Is that right?

jez234 · Oct 12, 2022

loz2754 said:
The Code of Practice for EV charging states that "Every charging point shall be individually protected by an RCD...."
Page 53.
In other words, not by an RCD that also protects other circuits.

Thank you

westward10 · Oct 12, 2022

jez234 said:
That's what he's been saying - that existing socket circuit had too much leakage and the PV system in addition is too much.
But you are saying it's unsafe and doesn't meet the regulations to be on the same circuit? I want to have a clear plan of what I need to ask for.
I think there needs to be an additional fuse board with an RCD each for the PV and charger? Is that right?

No it doesn't need an additional board I would replace your existing board and fit separate rcbos. The PV should not be on a shared rcd the installer should know this although the fitting of the Steeple mcb suggests otherwise.

jez234 · Oct 12, 2022

westward10 said:
No it doesn't need an additional board I would replace your existing board and fit separate rcbos. The PV should not be on a shared rcd the installer should know this although the fitting of the Steeple mcb suggests otherwise.

Yikes, that sounds expensive, no? Is there not another (safe and legit) way? Or am I missing something?

James · Oct 12, 2022

Your installer should be providing you with a fully compliant installation.
If it is not suitable to connect to your existing distribution board, they should have come up with a plan that suits you, your budget and remains compliant.
if the 3 things listed above can't be done at quote time, the job should not have been started.

jez234 · Oct 12, 2022

James said:
Your installer should be providing you with a fully compliant installation.
If it is not suitable to connect to your existing distribution board, they should have come up with a plan that suits you, your budget and remains compliant.
if the 3 things listed above can't be done at quote time, the job should not have been started.

Thank you. Yes I agree and assumed that this was what was happening.
Just hoping there might be another compliant option which would be less costly. Would an additional board with dedicated RCDs not be compliant (and a lot less work)?