PV install

[amo]

Evening all

I went to see a job today an electrician has fallen out with the client and we have been called in to complete the works. 90% of the works has been done, new rings, smoke alarms, kitchen, CCU, etc. It was a fly-by visit as the builders were finishing up for the day.

There is a PV install on the roof, this is fed down to a generation meter next to the CCU. The generated power will be used to supply CCU only, not to be fed back to the grid. The way it has been connected is through the 16a mcb of a split load RCD board. So the generated electricity passes through the mcb and powers just the circuits connected to that busbar. Is this allowed? I haven't really read much into PV and I can't find too much on-line.

In a hurry I didn't even take any pics but will be swinging by again on Monday so will take a few then. Didn't get a chance to go into the loft to look at the inverter either.

Will the install need to be signed of by a mcs qualified person? My main concern is if the RCD does trip, whats to stop the generated power still being fed to the circuits?

Thanks

 

[wersolaruk]

i think you need to read up about inverters etc they are all fitted with islanding devices, when grid voltage is lost inverter will automatically cut out, as for the supply going into the rcd side this is also ok as the energy will be pushed via the to either a different circuit fed of any circuit on that db or alternatively back to the grid, hope this helps

- - - Updated - - -

@inverter@

 

[Gavin A]

The way it has been connected is through the 16a mcb of a split load RCD board. So the generated electricity passes through the mcb and powers just the circuits connected to that busbar. Is this allowed?

Thanks

bad practice at best, likely to cause nuisance tripping, potential to cause the RCD to stick (depending on the inverter), potential to result in power from the inverter continuing to flow for a short time after the RCD has tripped in fault conditions.

ie it should really be connected to either a none RCD protected way, or on its own dedicated RCD / RCBO. There are lots out there that aren't, but there's a thread on here from customer who's rcd has kept tripping out, which should indicate why this really is a bad idea.

 

[SolarCity]

A PV system connected to a communal RCD is a bad idea for a couple of reasons. Nuisance tripping and safety issues.

If the RCD operates for whatever reason, the PV system will still be powering the circuits it is shared with for a brief moment. In a worse case scenario, a faulty inverter may even fail to go into islanding mode, thus creating a potential dangerous installation.

In actual practice, it's not likely to ever be an issue, but PV systems should be kept separate for those reasons.