Solar system compatible with 7671 CU?

[nisioptimum]

I installed a dual RCD 10 way Wylex CU for a customer about 2 months (had 3 spare ways not used)ago now they are thinking of having solar pv 4KW system installed. The "surveyor"/salesman said they would need a CU change to have solar installed. I have read the green book and cannot see why they would need a CU change. It is a TN-c-s earthing system installed with isolator switch just prior to CU change. Any advice from PV installers etc most welcome

 

[Hawkmoon]

Thought this post was about astronomy at first...

Not particularly expert on PV but I AM experienced in the sh1te that salesman spew so CU change not necessary - 4kw pfft

 

[nisioptimum]

Thought this post was about astronomy at first...

Not particularly expert on PV but I AM experienced in the sh1te that salesman spew so CU change not necessary - 4kw pfft

My view is exactly the same but customer told the supply from PV system different from the grid. I said how can they install it if it is not compatible with domestic supplies. Customer looks bewildered "because one comes from the sun the other from the power station?" I pointed her to some websites Martin Lewis' does have quite a good explanation and she knows him. I will wait and see but I am happy with the install and she has the certs and so do I.

 

[Meggerman]

Some installers wont put PV onto a RCD protected busbar with other circuits. If a earth fault developed on one of the other circuits and the RCD disconnected then the inverter could still back feed for upto 5 seconds onto that busbar and onto faulty circuit via MCB.

 

[nisioptimum]

Thanks Meggerman but what CU do you install?

 

[Meggerman]

Either put on RCBO if High Integrity board with 3 neutral bars or split tails with Henleys and install small DB just for the PV.

 

[nisioptimum]

Surely it is the PV company to make their system compatible with the fixed wiring not me. Good customer with friends so do not want to be upset.

 

[Meggerman]

Surely it is the PV company to make their system compatible with the fixed wiring not me. Good customer with friends so do not want to be upset.

Yeah definatly, it's not your problem. Is Wylex DB you installed high integ?

 

[nisioptimum]

It is this board
Wylex 10-Way High Integrity Consumer Unit & 10 MCBs | Wylex Consumer Units | Screwfix.com

So what board do they want. As I said there are 3 free ways if they want to re-arrange it is unto them they can move to have RCD or not protection.

 

[jackhammerJIM]

its a high integrity board so install an RCBO on the mainswitch side .

 

[JulianC]

Don't put pv on a shared RCD. Can be put on the non protected way of a high integrity board no problem. No need for RCBO unless installation method calls for it. Sticking it on a separate 1 way board is the usual way of doing it. If the company aren't aware of this, walk away.

 

[Hawkmoon]

Not versed in PV as I have said but why not have contactor in PV output - coil controlled by RCD circuit - RCD trips, output shut down...

Don't see why it has to be so elaborate.

 

[Gavin A]

It is this board
Wylex 10-Way High Integrity Consumer Unit & 10 MCBs | Wylex Consumer Units | Screwfix.com

So what board do they want. As I said there are 3 free ways if they want to re-arrange it is unto them they can move to have RCD or not protection.

well this one's easy - explain to the customer that the PV company haven't got a clue what they're talking about, and best to find another company.

A High integrity board with spare ways on the none RCD side is absolutely perfect for solar PV, there is no better solution.

 

[Meggerman]

That would not help, inverter output is in parallel with the grid The inverters shut down output within 5 seconds (G83) on mains loss.

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Not versed in PV as I have said but why not have contactor in PV output - coil controlled by RCD circuit - RCD trips, output shut down...

Don't see why it has to be so elaborate.

That would not help, inverter output is in parallel with the grid The inverters shut down output within 5 seconds (G83) on mains loss