PV/RCD problem

[MorganPVI]

You may want also to consider your voltage drop on a 10mm cable. The manual says 38.8m max on 10mm and your doubleplus. Even with a 100ma I think you may have the odd trip as your feeding into a very busy and distant CU on a cable that is spec'd for half the distance your streching it over.

 

[Spherenergy]

Morgan- Normaly we would do but in this job there is no room as the ecxisting board is in a small cupboard. I'll replace the main RCD for a 100 amp double pole main switch and put a small split load DB in the outbuilding. Hopefully this will solve the problem? Still not sure why the PV works with the other breakers off?
Thanks Morgan

 

[Spherenergy]

Sorry I posted that before I read your most recent post. I'm planning on not having any RCD protection on the PV. Half the split load for the RCD essentials the other half for the PV, garage DB and swimming pool supplies.

 

[JohnBoyZ]

Sorry I posted that before I read your most recent post. I'm planning on not having any RCD protection on the PV. Half the split load for the RCD essentials the other half for the PV, garage DB and swimming pool supplies.

I would have thought the garage and pool would have to remain RCD protected!.
One thing to bear in mind is that by connecting the inverter to currently protected circuits effectively makes them unprotected as the inverter has up to 5sec disconnection time.
From what you said, originally everything was protected by an overall 30ma RCD in the main building and i would suggest you keep it that way. I think you really need to find a way to run the PV through a small 2way CU with a 100ma RCD and connect that into the tails feeding the existing overall 30ma RCD. If you can't easily get new cabling through to the main building then could you change the main RCD for a 2 pole switch and move the 30ma RCD into the existing CU so that remains fully protected as it was originally. Put a henley on the supply to the existing CU in the outbuilding and connect in the PV via the new 100ma RCD CU into the henley.