Ping the solar installers

[Red'n'Black]

My Mum has just had a solar install done, not sure the exact spec but it covers one pitch of a 2 bed bungalow, so I'm guessing a couple of kW?

They finished wiring the inverter last week. Since then she's been having random RCD trips. I've said it could be a failing appliance or water ingress, but she's been there a year so far and no problems up til now, so it seems a bit suspicious.

I know we have a few members on here who do this for a living - any experience of high-frequency noise from the inverter causing RCD trips?

It'll be a week before I'm able to get over there and take a look myself, I've asked my sister to take some pics of the CU in the meantime so I can see how it's set up.

If it was a hard fault I'd tell her to just get a sparky in, but intermittent faults have a nasty habit of disappearing the moment a pro shows up.

 

[MetalMonkey]

Pictures would help. Is it one RCD covering all the circuits?

If so, sometimes you get a situation where tiny amounts of earth leakage from various devices adds together as a cumulative effect and then it only takes one extra piece of equipment to push it over the trip threshold - so it might not be one specific thing contributing.

 

[brightspark]

advice on here cant be given. its like how long is a piece of string. an insulation test on the wiring is needed and take it from there where to go next given the results on the circuits

 

[Red'n'Black]

advice on here cant be given. its like how long is a piece of string. an insulation test on the wiring is needed and take it from there where to go next given the results on the circuits

Yes I'll take the Megger with me when I next go over, I was just wondering if this was a known problem with some solar inverters as the timing was a bit suspect.

 

[brightspark]

Yes I'll take the Megger with me when I next go over, I was just wondering if this was a known problem with some solar inverters as the timing was a bit suspect.

the lousy part of testing is when nothing shows up on the meter another is unplug sky box and electronic equipment or the test at 500v will trash them . make sure you unplug surge protected leads as they will give false readings to earth . been there done it and got the tee shirt

 

[minimutly]

Doesn't have to be the inverter, could be the panels. But would need the whole cu to be on a leakage trip?

 

[Misterg]

It'll be a week before I'm able to get over there and take a look myself, I've asked my sister to take some pics of the CU in the meantime so I can see how it's set up.

Is it a split load board (i.e. part RCD protected / part not)?

If so, there's the old chestnut of returning the neutral to the wrong half of the board which will cause load related RCD trips.

 

[MetalMonkey]

If it is an issue with the neutral on a split board, the fault shouldn't be randomly intermittent, assuming what they have said is correct - which it may not be of course!

Problem on the DC side could be possible if it is a transformerless inverter, if so worth checking if it correlates with rainy weather. Cabling in gutters etc. Also it is possible to get a capacitance effect with the frame of the panels.

If doing IR checks, to be safe start at 250V - then if it tests clear proceed to your 500V, that way anything accidentally left in circuit will show up as a low reading, and you can then find and remove it before you have sent 500V up its chuff. If they say they have unplugged "everything", assume they haven't unplugged everything.

 

[Gareth J]

From experience, yes, they can do that. If not on a dedicated circuit, some inverters can throw trips. Often in dull/drizzle weather in my experience. So ideally, the inverter will be on its own supply from Henley blocks. Some inverters require 100ma RCDs, check the manual for it to see if yours does and that the install matches.

 

[minimutly]

From experience, yes, they can do that. If not on a dedicated circuit, some inverters can throw trips. Often in dull/drizzle weather in my experience. So ideally, the inverter will be on its own supply from Henley blocks. Some inverters require 100ma RCDs, check the manual for it to see if yours does and that the install matches.

Exactly what mine does - wet weather for days and it usually trips once at least.Needs a 100mA rcbo instead of the 30.

 

[gaz1]

My Mum has just had a solar install done, not sure the exact spec but it covers one pitch of a 2 bed bungalow, so I'm guessing a couple of kW?

They finished wiring the inverter last week. Since then she's been having random RCD trips. I've said it could be a failing appliance or water ingress, but she's been there a year so far and no problems up til now, so it seems a bit suspicious.

its the installers issue as you have only seen it since the system was fitted and wired in

so really its a call back job to sort it

 

[J1nx]

Does it have a rotary isolator fitted on the inverter AC supply? If so does this stop any tripping when off?

Photos might help.

 

[brightspark]

Is it a split load board (i.e. part RCD protected / part not)?

If so, there's the old chestnut of returning the neutral to the wrong half of the board which will cause load related RCD trips.

true but it would trip instantly due to imbalance every time you try to reset it

 

[Dave-sparks]

Exactly what mine does - wet weather for days and it usually trips once at least.Needs a 100mA rcbo instead of the 30.

If a 30mA RCD is required then no higher rating will do the job.

 

[Gareth J]

If a 30mA RCD is required then no higher rating will do the job.

Two bits from two different manuals.

I don't know why. But before I got them changed, the 30mA would trip often. Changing them solved it.

As it's been installed, definitely worth checking the installation manual to see if the recommended value RCD has been used.

 

[Red'n'Black]

its the installers issue as you have only seen it since the system was fitted and wired in

so really its a call back job to sort it

You might well be right. But I'm going to find out what exactly has been installed, go away and RTFM, do some basic checks of my own and get all my ducks in a row, before I start pointing fingers.

Pics to follow tomorrow, hopefully. The same company put in an air source heat pump back in January, that looks a neat professional job and works great so far.