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

[jez234]

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]

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

 

[jez234]

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]

Can you show a picture of your consumer unit.

 

[jez234]

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

 

[westward10]

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]

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]

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]

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]

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]

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]

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]

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]

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]

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)?

 

[SparkySy]

The easiest and cheapest work round option from what I can see is to remove the right hand RCD and mcb's and replace those 3 with RCBO's then use the two slots from the RCD for the solar and charger so only costing you for 5 Hager rcbos. This would then solve the issue with the wrong MCB that has been fitted!
Personally I would do what @westward10 suggests earlier and replace the whole lot with a new SPD protected type A rcbo populated board with some spare ways in for future expansion!
Sy

 

[solarpvman]

On the subject of Hager RCBO's specifically for Solar PV, they are not bi-directional. Meaning they can not be reverse fed and shouldn't be used. I had this confirmed by Hager technical support.
For my solar install I am going to use a separate RCCB (RCD) and MCB specifically for the solar PV circuit.

 

[Tim-Cx]

On the subject of Hager RCBO's specifically for Solar PV, they are not bi-directional. Meaning they can not be reverse fed and shouldn't be used. I had this confirmed by Hager technical support.
For my solar install I am going to use a separate RCCB (RCD) and MCB specifically for the solar PV circuit.

Do you have any recommendations for RCCB and MCB combination and CUs that you would recommend in this situation?

 

[solarpvman]

Do you have any recommendations for RCCB and MCB combination and CUs that you would recommend in this situation?

As you can appreciate each setup is unique in what you need to specify for over current protection and whether RCD protection is required.

If you are unsure, you should seek the advice of a professional!

That said, if RCD protection is required you need to establish if there is simple separation between the AC and DC side of the inverter(s). If there is not, a Type B RCD will need to be specified to respond to DC currents >6ma.

The RCD will also need to be double pole, so that protection of the circuit is not reliant on the shutdown characteristics of the Inverter(s).

The manufacturer of the Inverter will be able to provide specifics on the inverter characteristics which will inform the protection required.

The solar setup I propose uses Enphase IQ7A microinverters. They do have separation between the AC and DC circuits.
So, 11 IQ7A inverters will need a 20A MCB and a 2P Type A RCCB. These will likely be Hager branded.

It is worth checking with the manufacturer of the devices to ensure they conform to the requirements of the instillation.

 

[Tim-Cx]

As you can appreciate each setup is unique in what you need to specify for over current protection and whether RCD protection is required.

If you are unsure, you should seek the advice of a professional!

Indeed and I am, but a lot of electricians are not familiar with inverters either.

That said, if RCD protection is required you need to establish if there is simple separation between the AC and DC side of the inverter(s). If there is not, a Type B RCD will need to be specified to respond to DC currents >6ma.

I have confirmed that there is some internal protection, the manufacturer states that IF an RCD is required then it should be Type A but with a higher trip current.

The RCD will also need to be double pole, so that protection of the circuit is not reliant on the shutdown characteristics of the Inverter(s).

The manufacturer of the Inverter will be able to provide specifics on the inverter characteristics which will inform the protection required.

The solar setup I propose uses Enphase IQ7A microinverters. They do have separation between the AC and DC circuits.
So, 11 IQ7A inverters will need a 20A MCB and a 2P Type A RCCB. These will likely be Hager branded.

It is worth checking with the manufacturer of the devices to ensure they conform to the requirements of the instillation.

I think I misunderstood your original comment that Hagar RCBO's were not suitable, I assumed you meant Hagar in general but I think you just meant their RCBOs.