Can Solar panels cause tripping when isolated

[Eric12]

Anyone know if its possible for a rooftop solar array to cause an RCD trip even when the solar circuit is isolated at its rotary isolator ? I've had no dealings with solar atall so wouldn't know . The solar circuit is in a split load RCD board. I'm assuming the solar install was bonafide as its on a fairly newbuild. Stray earth current leakage from the panel/inverter perhaps ??? is this a known issue with solar ?

 

[PS Electrics]

Don't assume the Isolator is wired correctly see following video

View: https://www.youtube.com/watch?v=Tmgu7-5dlJQ
at 8:00

 

[brianmoooore]

Solar into a split load RCD board rings alarm bells as well, if it's a board with two RCDs and a main switch.

 

[littlespark]

you dont say if its just the DC isolator to panels, or the AC to the inverter...
what is the rating of the inverter, the cable size, ocpd size.....

Photos are good.

the problem with a "shared" RCD is that the feedback from the invertor may last longer in the event of an rcd trip than the specified 40ms, thus failing any rcd test.

 

[Eric12]

Thanks for responses, been away today hence no reply sooner. So yep the rotary isolator as mentioned is just above and fed from the CU mcb, so that would be the AC to inverter isolator. So if this was switched off then would/could the solar system still cause an earth fault to flow ? and yes its a split load board, not my install. Is it likely that a fault to earth could manifest via the panels or inverter (when the inverter feed is isolated) and find its way through the cpc feed back to the CU ?, or through any bonding of the solar system ? Do solar systems even have bonding ??? As I said im not familiar with solar.

Im not sure it is the solar causing this issue, the story goes thus:

I took a look at this when (customer - friend of a friend) reported nuisance tripping, the RCD in question tests fine on ramp test (19mA or so) and is feeding 4 or 5 circuits, one of which is the solar. Before removing the CU cover to look at the circuits I isolated the solar at the rotary isolator above the CU. with all appliances disconnected from the x2 rings on this side of the CU and all the lights on, my clamp meter was not picking up anything obvious from the cpc's of these circuits (clamp meter is a bit el cheapo thou). IR testing of these circuits was good aswell. However, one of the ring circuits was causing a trip when carrying out a 3 lead low loop test with all other circuits switched off. Switched off the boiler at the spur and loop test caused no trip, strange thing is my clamp meter was picking up no stray current to earth while the boiler was powered up via the rings cpc or any bonding. So, I said its likely your boiler has an earth fault that's intermittently tripping the RCD as earth leakage is accumulating with any other earth leakage from equipment and tipping it over the RCD's 19mA. I suggested getting all the equipment pat tested and your boiler looked at before doing anything else.

Since then and now customer has told me that her neighbours on her estate have experienced a similar tripping issue, and it seems that the solar panels have been causing it. Hence my original question. As the solar was isolated when I carried out the offending loop test assumed that it could not be a contributing factor; but thinking more the solar is always generating something isn't it , even when its isolated, so my question again, can there be leakage to earth from a solar panel array thats isolated on the AC side ??

Thanks in advance

 

[James]

I would be looking for a N to earth fault.
I have known this to be a fault that can cross between neighbouring properties that should have been electrically separate.

 

[littlespark]

I would take any suggestion from a customers neighbours (friends dogs sisters) with a big pinch of salt. Can lead you away from the actual cause. This is a different property.

You have said you found a ring tripping with other circuits turned off…. Try this again with the neutrals of those circuits disconnected as well as the lives.

 

[brianmoooore]

You have said you found a ring tripping with other circuits turned off…. Try this again with the neutrals of those circuits disconnected as well as the lives.

This! I would also explain to the customer the dangers of the PV being fed into a shared RCD. If the RCD tries to do its job by cutting off the power to someone who is being electrocuted, the PV will keep the circuit live for some time after the RCD has tripped.
This is one I've come across on many more than one occasion.

 

[Eric12]

I would be looking for a N to earth fault.
I have known this to be a fault that can cross between neighbouring properties that should have been electrically separate.

Possible, but unlikely really tbf. New builds are not that bad are they