Upgrade a Grid-Tied Solar PV System with battery. Solis RAI

[sharpener]

I had hoped I had made it clear, the pictures show the isolation switch etc. as it was all professionally installed & commission & DNO paper work etc.

I cannot image that the inverter sold into mainstream the UK does not have those protections build in on the backup circuit.
In the case of power failure from what I read it immediately isolates just that one circuit so no way it can feed back to the grid.
Its not as if trying to do the whole house on UPS.

Looks to me that the isolator shown in post #15 pictured upthread is the isolator required for the connection from the PV inverter, it is not the same as the isolator required between the battery system and the CU, you need both. A lockable double pole mcb is arguably sufficient for the latter (though IMO is not really the intent of the IET CoP) and in practice many ppl fit another rotary one right next to the battery charger/inverter.

Are you going to change the wiring between the meter pictured and the isolator to avoid AC power derived from the battery showing on the meter? Or have I misunderstood the topology?

I am going to read Nowty's link but from my current position of ignorance I cannot see how a live to earth leak would affect an RCD by having two bonded earths.

Yes it is explained there but the key point is that for the RCDs to provide the protection but not nuisance trip there needs to be one and only one neutral-earth bond in the system. So when the mains is present the bond relay in the invert must be open, and if not then closed.

You are now allowed to have your earth electrode wired in parallel with the PME earth provided by the DNO but it does not change the position regarding the neutral-earth bonding.

[sharpener]

I had hoped I had made it clear, the pictures show the isolation switch etc. as it was all professionally installed & commission & DNO paper work etc.

I cannot image that the inverter sold into mainstream the UK does not have those protections build in on the backup circuit.
In the case of power failure from what I read it immediately isolates just that one circuit so no way it can feed back to the grid.
Its not as if trying to do the whole house on UPS.

Looks to me that the isolator shown in post #15 pictured upthread is the isolator required for the connection from the PV inverter, it is not the same as the isolator required between the battery system and the CU, you need both. A lockable double pole mcb is arguably sufficient for the latter (though IMO is not really the intent of the IET CoP) and in practice many ppl fit another rotary one right next to the battery charger/inverter.

Are you going to change the wiring between the meter pictured and the isolator to avoid AC power derived from the battery showing on the meter? Or have I misunderstood the topology?

I am going to read Nowty's link but from my current position of ignorance I cannot see how a live to earth leak would affect an RCD by having two bonded earths.

Yes it is explained there but the key point is that for the RCDs to provide the protection but not nuisance trip there needs to be one and only one neutral-earth bond in the system. So when the mains is present the bond relay in the invert must be open, and if not then closed.

You are now allowed to have your earth electrode wired in parallel with a PME earth that is provided by the DNO but it does not change the position regarding the neutral-earth bonding.

[openspaceman]

Yes it is explained there but the key point is that for the RCDs to provide the protection but not nuisance trip there needs to be one and only one neutral-earth bond in the system. So when the mains is present the bond relay in the invert must be open, and if not then closed.

You are now allowed to have your earth electrode wired in parallel with the PME earth provided by the DNO but it does not change the position regarding the neutral-earth bonding.

Okay I think I have got this now; because the output from the EPS of the inverter is isolated from the house neutral and live and is not normally earthed, in normal use it cannot be bonded to the earth (and consequently the neutral). Once islanded the neutral is bonded to the house earth for normal safety.

Is this because inverters are designed to meet regulations elsewhere ( perhaps with lower voltages like US) and as such do not fit in with UK arrangements?

Still reading the document, takes me a while to assimilate tech stuff nowadays.

[Bignose2]

Hi,

Thanks again, sorry been busy with some other stuff.

That looks almost exactly what I need to do, separate housing as no room in the CU.

I think a slightly different meter is now supplied but guess same principle & likely connections. Estron SDM630 mentioned.

And you refer to getting power from a lighting circuit I think answers my question ...
does the grid + & - connection into the meter really just for powering the meter itself & perhaps getting the voltage, i.e nothing is passing through to get the amps or anything so does not matter where it is connected to the grid.

[MrPablo]

That's exactly right, it'll be powered from the circuit (very minor load) and getting the voltage reference.
The current reading will be via the CT clamp.