question about CU with solar PV

[nbhare]

Have not come across a consumer unit with solar fitted before, have been asked to replace the CU, at the moment the CU is a old plastic type with a RCD fitted covering half the circuits, I will be fitting a 17th amm3 CU, now, the question I have is, im presuming the 16A mcb that is currently coming from the solar needs to be fitted independently of any other circuits on its own busbar (because of the disconnection time) but the question is, and excuse me if im being dumb, the power from the solar enters the CU via this MCB, if its not on the same busbar as anything else how can the power be used?

there is a solar Iboost fitted also to the immersion heater/tank, surely if the solar isnt on the same busbar how will the power be utilised by the iboost?

finally, how is the solar MCB treated with regards to testing and filling in the EIC

thanks,

 

[Leesparkykent]

Any pv guru’s on here that can provide a more expert opinion on the shut down times of a pv inverter?

I haven’t got regs book with me but I believe it’s around 551.7.2

 

[Ian1981]

I haven’t got regs book with me but I believe it’s around 551.7.2

Spot on regarding the regulation number

 

[Wilko]

So as a learning exercise I had a look about and found a few numbers for "anti islanding" disconnection times. This is the Loss of Mains spec where the invertor recognises that mains has been lost and shuts the invertor down. The disconnection times ranged 0.5 sec to 2.5 sec (didn't sort out why, sorry). It appears this is tested on installation, but there is no periodic test that I found. I understood intention is to protect DNO workers. The householders rely on us to not connect the invertor in a silly way that defeats ADS disconnection times.

 

[Octopus]

So has this thread concluded that Solar should never be connected to a CU where the circuit is on a shared RCD or a single pole RCBO?

If so, that means nearly all the solar installations I have come across don't meet the requirements of the regs......

 

[Ian1981]

So has this thread concluded that Solar should never be connected to a CU where the circuit is on a shared RCD or a single pole RCBO?

If so, that means nearly all the solar installations I have come across don't meet the requirements of the regs......

Basically yes.
If connected to an rcbo then the rcbo needs to be double pole.

 

[Leesparkykent]

Basically yes.
If connected to an rcbo then the rcbo needs to be double pole.

Or single pole switched neutral?

 

[Leesparkykent]

Only if additional protection is required. Most I’ve done have been up the gable end wall in a bit of conduit.

 

[ChrisElectrical88]

Seen lots of PV installs in council owned houses. Every one of them on thir own SP RCBO from one of the two non RCD protected circuits available. Every board was a 2x5x5 duel RCD.

 

[Ian1981]

Or single pole switched neutral?

yes all live conductors require disconnection If an rcd is used for additional protection