Inverter AC Supply RCBO Tripping

muckyba

Hi all,

Been following these renewable threads for some time now, and there is always some great advice and guidance provided by the many great contributors, and unfortunately I am needing to tap into that right now.
I had a 7.4KW PV system with battery installed last August, but what I have noticed is that, when there is extremely windy weather, that the inverter AC supply RCBO trips. This has happened regularly throughout the winter when the weather has been stormy, think of all of the orange wind alerts throughout the winter/ spring and the tripping usually aligns with these. Even in the heaviest rains, this did not trip the RCBO, it only seems to happen when there are strong winds.

My next door neighbour had the exact same system installed by the same installer at the same as mine. We have experienced tripping at the exact same time on occasions where there are high winds (and have recorded evidence of this twice, once over this weekend and another time in Sept 2023, when looking at the app or UI, they appeared to trip and lose connection to the PV system at the exact same time, e.g. 15:00 on Saturday).

Another neighbour who had a recent install, pretty much the same system but a different installer, didn't have any tripped RCBO on Saturday.

Could it be the inverter AC Supply RCBO itself? This is an Hager AD925J B25. Inverter is Solax x1 hybrid g4

Any guidance or insights into what could have caused this?

Thanks in advance for any assistance.

S'

I had the same issue in wet windy weather. The RCBO would trip. Changing out the 30mA RCBO to an 100mA version sorted the issues, hasn’t tripped the last few months

10-10-20

It the panels were wet at the time then it's probably the parasitic capacitance issue. It's probably worth a thought as to how wind might also affect capacitance between the panels and the frame as the movement of wind might add a factor in the equation.

https://www.boards.ie/discussion/2058326679/parasitic-capacitance

I don't think that the 'official' answer is to up-rate the RCD from 30mA leakage to 100mA, but some on here have suggested that this is probably going to be the default protection level anyway from some point forward, so maybe it's an acceptable solution for many. The recommended workaround from the manufacturers is to bias or compensate the RCD by fitting a suitably sized capacitor as documented on page 6 of the SMA guide attached in that thread above.

Hope if helps.

allinthehead

https://www.boards.ie/discussion/comment/121992450#Comment_121992450

I would add that adding a capacitor to an rcbo is something that I wouldn't do without checking with Safe Electric first.

SD_DRACULA

https://www.boards.ie/discussion/comment/121992450#Comment_121992450

Not sure Irish regulations allow the use of 100ma instead of 30ma so would need to check with a proper electrician.

muckyba

Thanks all, this is all very helpful information.

I won't be making any of these changes myself, I intend on getting the installer to look into and remediate the issue for me.

However, I am reluctant to take his word for anything at this stage as everything has been extremely drawn out, and I don't trust he will debug correctly and wil try to blag me off.

I am slightly confused in the way this is set up to be honest, my understanding is that there is a RCMU within the inverter, so is there need for a RCBO? Based on SEAI guidelines,

"Where an RCD is used for protection of the PV a.c. supply circuit, The RCD shall be of type B according to I.S. EN62423 or I.S. EN60947-2-, unless:

- the inverter provides at least simple separation between the ac side and the dc side or
- the installation provides at least simple separation between the inverter and the RCD
by means of separate windings of a transformer; or
- the inverter does not require a type B RCD as stated by the manufacturer of the
inverter."

The RCD used on my install is a type A (this is the type recommended / approved for use by Solax), however the recommended rating is at 100ma. Obviously the regs won't allow for 100ma so not sure how this can be handled.

I have attached guidance from Solax on this also for reference.

The installer might say that its installed as per regs and design, and therefore is nothing further he needs to do.

I'm a total novice on this so don't want to get the run around by the installer, would like to give myself the best chance possible of getting it resolved without incurring any costs (if possible), or the minimum costs if necessary.

Aprreciate all contributions, and apologies if what I have stated doesn't make total sense. Thanks.

RCD’s principle & basic application.pdf

SD_DRACULA

https://www.boards.ie/discussion/comment/121995160#Comment_121995160

You should have both an mcb and rcd, I have 32a mcb and 40a rcd noark brand and never had any issues with either solis or sunsynk inverters

micks_address

i have inverter power supply tripping the rcbo as well.. still do but its very intermittent. First time it started happening was last june after we had a prolonged period of dry weather and then downpours of rain - happened few times.. got onto the installer and they came out and checked all the wiring connections on panels etc and no water ingress. They did upgrade the 25 amp rcbo to a 30 amp one.. that seemed to solve the issue but it has tripped twice since.. no major weather going on at the time. Had an electrician over recently and he was wondering why they didnt go to 40amp.. he said he'd change it over for me at some point. Might get him to if it becomes an issue again. Our system is givenergy 5.5kw inverter and 7.2kwh panels.. i dont mind it tripping when we about - just always seems to happen when we away from home so end up losing out on a days solar generation.

Mr Q

https://www.boards.ie/discussion/comment/121992450#Comment_121992450

I changed mine from a 30mA to a higher rated leakage version to fix some tripping, hasn't tripped since.

But I also based this on what is in the SMA manual. So even they must different views on it in different documents

micks_address

https://www.boards.ie/discussion/comment/121997553#Comment_121997553

can i ask what you went to? 100ma seems a big jump as others have done

Mr Q

https://www.boards.ie/discussion/comment/121997700#Comment_121997700

I would need to check but I think all the wholesaler had in 32A was 300mA.

I'm adding another inverter shortly so will be changing it again if it is not 100mA.

muckyba

Thanks all. I think I’ll change it to 100ma and see how I go, hopefully this will solve the issues.

10-10-20

https://www.boards.ie/discussion/comment/122025558#Comment_122025558

Would you/your electrician consider doing the capacitor modification as a test? I think I can help with the calculation and it would be a good test.