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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,
 
Are you thinking that the supply to the P.V busbar never comes into contact with the other C.U busbars?
see this is what i mean, it was a daft question, of course, if its on its own busbar its still connected to the main switch, which is in turn connected to the RCD covering the first half of the board by the split load cable and in turn to the 2nd half of the board from the top of the first RCD to the top of the 2nd.

in which case should the solar mcb be on its own rcd/rcbo?
 
Your testing the fixed wiring, not the invertor.
Treat is as any other circuit up to the isolator before the invertor.
You will have to note that there are 2 incoming supplies in the appropriate check box
 
Our company have that problem on a new build site in that a pv company and I use that term loosely have just fitted a 20 amp mcb on the dual rcd board and fed the inverter via the AC isolator and metering from one side of the rcd.
Of course when someone gets an electric shock and the rcd trips within 40ms then the poor sod can still receive an electric shock until the inverter cuts out , which I believe can be upto 5 seconds.
Im required to write an email to the builder stating why the work carried out by the pv company is unacceptable
 
... when someone gets an electric shock and the rcd trips within 40ms then the poor sod can still receive an electric shock until the inverter cuts out , which I believe can be up to 5 seconds.
Hi - completely agree, but I wonder if the invertor might just keep on inverting while the sun shines? How does it know to stop, ever?
 
Hi - completely agree, but I wonder if the invertor might just keep on inverting while the sun shines? How does it know to stop, ever?
The inverter detects that the AC supply has disconnected and then shuts down.
I believe it’s called islanding but don’t quote me on that term.

Potentially dangerous in my opinion if connected to an rcd on a dual rcd board
 
An RCBO is no good if it’s providing additional protection as it’s a micro gen set and all live conductors require disconnection. Will be ok if the RCBO is SPSN but these are rarity. The only SPSN RCBO’s I’m aware of are SBS compact RCBO’s, Garo or Wylex compact RCBO’s. Of course you could use a double pole RCBO but not really designed to fit in a standard high integrity board.
 
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.
 
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.
 

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