Solar RCD tripping - no strings attached

[nxn]

Hi all. A year or so ago, our solar RCD started tripping in wet weather and in the last few months, it consistently trips every time it is reset.

I tried disconnecting one string at a time and then both, but it is still tripping. Is this down to the inverter (I understand PowerOne's are susceptible to current leakage), or could it be something else?

Installation: 2014
Inverter: 3.6TL Aurora Power One
Panels: 16 x Hyundai 250W Monocrystalline

 

[binky]

The earlier Power Ones were fine, I have one of those myself. The later ones were re-engineered by ABB after they bought out the company, and are dreadful for eath leakage. You need to fit a 300mA RCD according to ABB, personally, unless there's a very good reason for having the RCD, I would take the RCD out altogether, or change for a new inverter such as Solis.

Just to clarify, is the RCD shared with any other circuits?

 

[nxn]

No, the RCD is only used by the solar.

Changing to a 300mA RCD sounds like a cheaper/easier option, so I'll look into that one first.

Are Solis inverters what you recommend? I was looking at Solax X1 Boost as they come with a 10y warranty as standard, do you have any experience of them?

 

[nxn]

I've just checked, it looks like there is only a 30mA RCD fitter now!

 

[binky]

Solax are also OK, I'm not a great fan of Chinese inverters, but you can't argue with the prices.

I forgot to say earlier that if the problem is only when the weather is wet it would be worth checking over the cct to the inverter as it does sound like possible moisture ingress.

CHINT, other wise known as Chinese nasty trash! If the cabling to the inverter is run surface mounted in trunking, through underfloor cavities and generally deeper than 50mm from any surface you are likely to bang a nail into to hang a picture, then it is probably surplus to requirements anyway, and can be done away with. I've always installed cabling to avoid any possible requirements for an RCD to be fitted.

 

[Stuboy1]

Go and check every mc4 connector, i have one that when left on the ground pops the RCD, if i suspend it in the air it doesn't! Took it apart (at night) and you could see moisture had seeped past the o ring. It only needs a very small amount! Might be worth adding a smidge of vasaline around each o ring when u reconnect them. If it pops with nothing connected and I mean nothing at the actual inverter DC inputs then clearly its an inverter problem (if you find out what it is let me know as i have an ABB with exactly that fault in the warehouse somewhere!).
Good luck and let us know what the actual problem turned out to be.
Cheers

 

[binky]

Moisture in the DC side should show as GFI - little red light on the front of the inverter accompanied with the message Riso low on the screen. But those inverters were never the same after ABB bought out the company, they recommend fitting 300mA RCDs and I've seen them trip 30mA after only a year or two, ABB seriously messed the electronics up and I stopped fitting them as they caused too much trouble