Parasitic Capacitance.

He means blinded by way of having a bypass current over the RCD so that the overall trip current is therefore greater as some bypasses the measuring coils within the RCD.

Anyway the answer in my opinion is yes it can as it's only offsetting for a parasitic current anyway, so the difference is negligible when the compensation current calculated correctly.

The relationship given is:

Differential current = leakage current + residual current - compensation current

• Differential current = the trip current observed by the RCD and identified to be 15mA to 30mA for a 30mA A-type RCD.
• Leakage current = the cumulative parasitic capacitance of the panels overall.
• Residual current = the circuit/inverter residual current loss.
• Compensation current = The calculated offset current to offset the leakage current.

If the compensation current is oversized then it's my understanding that it's hiding some of residual current and potential fault-current, so the RCD is less sensitive to a true fault condition.

So 150nF would be suitable for offsetting 11mA if the cumulative parasitic capacitance of the panels is 11mA but not if it's less.

That's my take on it.

Not an electrician and not sure if this is related, but I had my installer out a few months ago to look at something like this. I was replacing an end cap on one of my roof mounted rails when i got a small tingle of it, it was a very wet day. They measured about 90V ac when checked with a multi meter between the ladder and the rail. The installer has no clue where the ac current was coming from. After a few visits, they eventually grounded the mounting frame and I have no issues since. I didn't get any inverter trips or faults before, only really noticed as I was replacing the end cap.

Thanks, just read that now and I recalled that they were also getting a voltage between the wet slate roof and earth!

Whilst I absolutely agree RE Earthing, the funny thing is IS:10101 does not require earthing of metallic array components unless they're in contact with metal components that are connected to the building earth (e.g. metal roof and drain pipes, structural steel etc.). Even many metal shed roofs get away with it according to IS:10101 as many aren't earthed...

I have noticed this intermittent tripping of the RCCB when it starts raining since I swapped out a Solis inverter for a Deye/Sunsynk. Would the type of inverter be causing this?

BTW, I have a Hager 63A 30mA RCCB

The issue is very similar to non-earthed 2pin mains connector Switchmode power supplies. With very close coupling of the high frequency tranformers, the output would tend to float up to 300v dc value of the mains input.

The 2 pin reversible connection means the manufacturer cannot designate either of the pins as Neutral and then so discharge the output leakage to neutral. So what they do is create a rough midpoint voltage with capacitors between L and N, which usually measures about 90-110v, and link the output to that. So its a lot better than 300v.

TV,Video equipment is notorious for this, and lots of othe small mains powered devices, usually ITE. Ever notice all laptops now have a 3pin plug..

Theres nothing to stop users from adding a bigger capacitor to neutral, and thats effectivly what the extra capacitor does for your solar system. It does bring in some other issues tho..!

Hi All, just to flag on this RCD/RCBO parasitic capacitance tripping issue. The wiring regs have now been updated as of this week to allow 100ma RCDs for microgenerators specifically.

I was double checking IS:10101 to confirm that the regs definitely demanded 30ma as my array and a neighbors were both tripping over the summer (I even put a residual current monitor on the line and correlated the parasitic leakage current to the rainfall rate at my automatic weather station 🤓). As I already had a copy of the standard, I got an email from NSAI when it was amended, so I checked that clause to see if they'd updated. In summary, I need new hobbies.

Has anyone swapped out the 30ma for a 100ma RCBO and has it resolved the issue?

Mine original 30ma has tripped 5-6 times over the weekend due to the weather.

Thanks have you found any supplier that has a 32amp 100ma RCBO? I know this is not a DIY job as its connected to the consumer unit and needs to be fitted by a RECI.

I fitted a higher ma RCBO a couple or years ago when having this issue. Hasn't tripped once since then.

Does someone have the hager model number for the Hager 1P+N 6kA 100ma version of the 1P+N 6kA 30ma?

Just wondering did you get to double check this?

I believe this one should be correct.