earthfault?

[LindaSecker]

Hi all

I've had a PV system on my house roof around 8 years. Excess goes into the grid. Professionally installed. Recently, I'm getting a red light and 'warning - Earthfault' coming up on the inverter. I've tried to find out about grounding and I'm not aware there is any, unless they grounded it to the house somehow (we have a cellar) It only happens in wet weather. What could this warning mean? Should I be worried?

 

[hwy17]

It sounds like a GFCI/RCD trip. But what is the exact model of device giving this error?

 

[LindaSecker]

goodness that was quick... it's a SunnyBoy inverter. I looked it up in the manual and it just said call the installer. They are no longer in business

 

[kommando]

Which Sunny Boy inverter ?

The TL's are a lot more sensitive to grounding issues than the earlier plain SBXXXX's

 

[LindaSecker]

SB 1200

 

[kommando]

That's an early one so much more likely there is a fault either in the external wiring or inside the inverter rather than a TL just being too sensitive.

So Riso / Earthfault means you likely have a fault in the panels or their wiring, this is high voltage DC which is more dangerous than AC so best checked by an electrician. Do not touch the panels or their wires but you could see if any are rubbing against the frame of a panel. If the electrician checks it out as being ok then the inverter must be at fault. SB1200's are available on ebay.co.uk at reasonable prices so just swap it over.

 

[RCinFLA]

Not the only cause, but a common cause of ground faults on PV arrays is delamination of backing plastic seal to glass near edges of panel.

Moisture intrusion into the delamination creates a path for electrolysis to build a conductive dendrite between grounded PV panel frame and PV cell connections within panel.

There are flat wires strips very close to the edge of panel on short side of panel closest to backside junction box. This is often where leakage path develops.

You can find this by disconnecting panel and measuring resistance from positive and negative terminals of panel to panel's metal frame. Should get an open circuit, or at least greater than 200k ohms resistance.

 

[LindaSecker]

thanks so much for your replies.... I'm clueless, so I think I'll have to call a professional.. looks like scaffolding going up again

 

[SeaGal]

looks like scaffolding going up again

Just playing devil's advocate here, as I'm not familiar with SunnyBoys (before my time ), but before incurring scaffold costs, could the inverter report an earthfault due to an issue on the AC-grid, rather than PV side... @kommando ?

 

[Hedges]

Maybe just a glitch. Go through the commissioning process to reset it.
Does it have a GFCI fuse? Maybe not for this model.
If like my SWR 2500U, there was a sequence with fuse removed, then replace it and proceed per instructions.
See what the manual says for your model. (looks like just turning it on is all yours needs.)

With both PV+ and PV- of array isolated from inverter, measure voltage between PV+ and ground, PV- and ground. It might read a few hundred volts but should decay to zero, small capacitance discharging into 10M ohm meter.

If voltage remains, there is a fault, e.g. damaged wire or leak in PV panel.

See page 36, 37. There is mention of a varistor that can go bad, maybe used rather than fuse for this model.

https://www.solartradesales.co.uk/Cache/Downloads/SunnyBoy-SB1100-1200-1700-Installtion-Manual-3.pdf

What model PV panel? A few have been noted for developing leakage to frame. Trina had that problem at one point and recalled it.

If you rule out PV array, could be picking up a used replacement inverter is easiest fix. Or look for a newer hybrid compatible with same PV array, or reconfigured array, and go for a battery backup system.

 

[kommando]

An 8 year old install would not be a new SB1200 but was a used one as they were out of production and the TL's were the current model then. The old SB1200's were with transistor's unlike the TL's (TL standing for Transistor Less) and unlike the TL 's are very earth fault tolerant especially AC to DC. I have 5 SB1200's with 2 running at any time and never seen an earth fault, my SB3600TL-21 can throw earth faults at the drop of a hat. The normal faults that take out plain SB's are the DC relays and the Varistor. They are now so cheap 2nd hand you don't bother repairing them but swap out old for less old.

And in the UK its rare to see the panels earthed anyway.

 

[LindaSecker]

thanks Seagal, Hedges and Kommando... I've no idea what panels they are but as I was looking out all the bumf for the system, I find it was installed TWELVE years ago! Where does the time go? Did I mention I am clueless? Anyhow, before I order scaffolding (again...) I'm gonna get in touch with someone locally who does PV installs and see if he will have a look at it. Hopefully he can check out all this stuff from indoors before he has to go on the roof

 

[kommando]

Yes someone with PV experience can do some basic trouble shooting at the Inverter. If it is the inverter then there is one for £55 in Northwich where you would have to pick up.

SMA Sunny Boy SB1200 Solar PV Inverter 1.2 KW 1200 Watts | eBay

Sunny boy sb1200 in good condition.

www.ebay.co.uk

plus others for more but delivered.