RCD tripping

[Nora Battery]

Hi, could I ask for some advice following installation of solar panels, inverter and battery earlier this year? Since the system has been installed and commissioned, the master RCD breaker trips frequently/randomly.

What happened prior to the install?

We’ve lived in the house c.10 years and the RCD seldom tripped. The only time I can remember the RCD tripping was when an old kettle reached the end of its life. New kettle solved the problem.

How old is the house?

Built 2002, extended 2007

What was installed?

12 No. Jinko JKM400N 400w panels

1 No. GivEnergy hybrid inverter

1 No. GivEnergy battery 8.2kWh

What’s happening now?

The master RCD breaker has started tripping intermittently since the install and commission. It mostly trips when we turn on the washing machine in the garage, but sometimes trips for no obvious reason. Sometimes we can turn on the washing machine in the garage and everything works fine. The problem seems random/intermittent.

Any remedial action taken?

I raised the issue with the installers when it started soon after installation. Their electrician guy tightened the screws on the breakers in the garage (there is a separate consumer unit for the garage) and checked the breakers on the main board. He also pulled the washing machine out and checked the plug/socket behind it. That didn’t seem to resolve the problem.

Who did the install?
Local company, who are reputable. I’d rather not name them.

What happens now?

I don’t really know where I stand. The RCD problem wasn’t there before the solar panels were installed, so I would hope the installation company will fix it. But the installation wasn’t exactly problem-free (long story but happy to divulge if it helps) so I don’t have huge confidence in them. Should I call out a different electrician and ask for their help/opinion? But why should I be paying someone else to fix a problem which the solar installers seem to have caused? Getting hold of the solar installers is hard now as they are so busy with other installs.

Is there a warranty?

Yes, manufacturer’s warranty on the kit and ten-year warranty on labour.



I’m not very electrically tech savvy (wiring a plug is about the extent of my skills) but any advice gratefully received. Thanks NB

 

[John Frum]

If you are comfortable removing the cover of the consumer unit please post a picture so we can see if anything looks odd.
Also what grounding strategy is your house using.
Common options are TT, TNS and TNCS.

 

[Nora Battery]

A few photos attached. I'm not sure what the grounding strategy is sorry, I've included pictures of the garage consumer unit, main board, meter box and outside if that helps. Many thanks.

 

[Mattb4]

Just a guess. Your hybrid inverter does not play well with the RCD. Converting DC to AC can involve some strange current paths. Your solar installer might have to change the setup to prevent nuisance tripping.

 

[SeaGal]

Did you get this resolved? Just asking as am on another thread with similar issues - thanks.

 

[Steve Fractals]

I'm also getting nuisance trips. With mine (completely DIY) it seems to just be once a week or fortnightly. Its like something builds up over time but checked all wiring and cannot find any poss fault. Sometimes it trips the main breaker and other times the inverter throws an F51 fault.

 

[SeaGal]

@Steve Fractals - main house RCD? Where is your inverter connected?

 

[Steve Fractals]

@Steve Fractals - main house RCD? Where is your inverter connected?

I have my solar circuits completely separate from grid except that I have a grid in to inverter to use bypass. I get the trips on either the F51 fault on the invertor or the main solar distribution box breaker trips. I am suspecting some kind of earth leak and this is somehow building up over the days until it trips one or the other.

 

[meetyg]

Maybe a ground loop? Does your inverter automatically bond N-G ? Or maybe it has an internal bonding screw that needs to be removed ?
I know some recommended to install Invert AC IN before the main RCD, but after main breaker, with its own MCB.

 

[Steve Fractals]

Maybe a ground loop? Does your inverter automatically bond N-G ? Or maybe it has an internal bonding screw that needs to be removed ?
I know some recommended to install Invert AC IN before the main RCD, but after main breaker, with its own MCB.

I can see no ref in the manual to bonding of N-G or anything to remove etc. The AC-In is fed from main consumer/distribution panel and that never trips. All my circuits out from the inverter are completely separate to any other house circuits and on their own disto panel. It is the main breaker of this solar distro panel that trips but only once per week or less. My inverter is the MPP PIP6048MT and is off grid in the respect of that the AC-in for it is supposed to be only in and not bi-directional. I am however sharing the grid earth with the invertor so maybe I need to install a separate earth/ground rod for the invertor as maybe it is some kind of ground leak.

 

[SeaGal]

The AC-In is fed from main consumer/distribution panel and that never trips.

Interesting that it doesn't trip, even when exporting.

All my circuits out from the inverter are completely separate to any other house circuits and on their own disto panel. It is the main breaker of this solar distro panel that trips but only once per week or less.

Assume that is 30mA RCD then? Any pattern to when it trips?

so maybe I need to install a separate earth/ground rod for the invertor as maybe it is some kind of ground leak.

Do you have TT earthing at your property?

 

[Steve Fractals]

TT earthing

Interesting that it doesn't trip, even when exporting.
I don't export anything = any excess solar is stored in batteries.

Assume that is 30mA RCD then? Any pattern to when it trips?
Yes

Do you have TT earthing at your property?

Interesting that it doesn't trip, even when exporting.

I don't export to grid.

Assume that is 30mA RCD then? Any pattern to when it trips?

Yes

Do you have TT earthing at your property?

No its a TN-CS system.

 

[SeaGal]

I'm not an electrician, but if it were me, I'd be wanting to identify the cause of the tripping, rather than plastering over the issue with extra ground rods. Tripping once a week is more than the typical "once-a-year-nuisance-trip-due-to-those-pesky-inductive-loads-all-switching-on-at-the-same-time".

Just adding ground rod by the inverter and keeping its grounding as TN-C-S sounds OK, as that is just PME, but I'd question whether it would be good practice to disconnect the grid earth from the inverter and convert that part of the circuit to TT, as you implied above. But, as I say, I am no expert, so might be good idea to get a sparky in to test for earth continuity and leaks etc.

 

[Steve Fractals]

I'm not an electrician, but if it were me, I'd be wanting to identify the cause of the tripping, rather than plastering over the issue with extra ground rods. Tripping once a week is more than the typical "once-a-year-nuisance-trip-due-to-those-pesky-inductive-loads-all-switching-on-at-the-same-time".

Just adding ground rod by the inverter and keeping its grounding as TN-C-S sounds OK, as that is just PME, but I'd question whether it would be good practice to disconnect the grid earth from the inverter and convert that part of the circuit to TT, as you implied above. But, as I say, I am no expert, so might be good idea to get a sparky in to test for earth continuity and leaks etc.

Thanks for the advice.

Having done some more research on the poss of a separate earth rod, it seems that to get full TT which wasn't my intention is very difficult to properly do anyway given the 10M away from any underground metal water pipes etc. I was thinking more of the extra ground rod and keeping TN-C-S but after further reading seems pointless in my situation. This what I am calling nuisance trips is more like monthly on the RCD but weekly to fortnightly the inverter throws an F51 fault which I'm working with MPP to solve. I have a feeling this is invertor related rather than any wiring as I've triple checked all the wiring.

 

[ns31]

Thanks for the advice.

Having done some more research on the poss of a separate earth rod, it seems that to get full TT which wasn't my intention is very difficult to properly do anyway given the 10M away from any underground metal water pipes etc. I was thinking more of the extra ground rod and keeping TN-C-S but after further reading seems pointless in my situation. This what I am calling nuisance trips is more like monthly on the RCD but weekly to fortnightly the inverter throws an F51 fault which I'm working with MPP to solve. I have a feeling this is invertor related rather than any wiring as I've triple checked all the wiring.

Hi was this inverter related? What was the outcome?

 

[SeaGal]

What was the outcome?

Yes... it's sad when we don't hear an outcome - it's good not just for closure on the people that spend time helping others, but also useful reference for other member/visitors in the future.

 

[RCinFLA]

RCD's trip when a small amount (<5 mA) of leakage current is passed through an alternate (safety ground) path. It checks for matching current on hot and neutral return. This pertains to loads downstream of RCD breaker.

There are two typical leakage paths to ground on PV / inverter systems. PV panels can have some leakage from PV cell connections to panel frame from delamination of plastic backing seal when moisture intrudes into the edge delamination.

Other leakage path is EMI (RF interference) filters put in inverter AC input and AC output ports to reduce switching noise escaping onto AC port wiring. The small value RF filter bypass capacitors are connected to inverter case ground creating a small AC leakage path to ground. You should not have RCD (GFCI) breakers upstream of inverter.

 

[Steve Fractals]

Sorry if I didn't come back with the outcomes earlier.

I had 2 issues. One was a faulty board on the inverter causing F51 or was it F52 faults and the other was I was using the wrong type of RCD. I was advised from this group on a PM to swap the breaker over to a Class Type A. I swapped to the type A and that immediately solved the tripping of the breaker issue and then a bit later on MPP sent me a replacement board to solve the F51 inverter trip faults.

 

[SeaGal]

Result!

 

[belgrano]

I also have same issue, small add on inverter is wired from the house 30m/a rcb trip. then a first light the inverter wakes up it tries to raise voltage to force generated AC into the circuit/grid. The sensitive trip, then activates on this imbalance.
Also found out that they should be on own supply and not through the main house supply. This was a heritage line that just was not changed.
Having a mains isolator and a henley block fitted soon to allow for seperate take offs, like solar, EV charging, and gives option to go off grid if it fails.
I'm now practically self sufficient on power.