Solar panels Tripping RCD when it rains

Alan_Brown

Does anyone have this problem? When it rains our panels trip the RCD which is a major pain because I then have to turn off the panels via the DC switch to avert the wrath of the missus. We had the panels fitted in January and they seem to have always done this.

The solar company who fitted our panels said that we should probably have them on their own RCBO instead of the main consumer unit. Would this fix it?

Incidentally, even though its just been installed since January, our power tracker shows a dip in our electricity usage for Jan & Feb for the first time in years (it has been steadily and gradually increasing, despite my best efforts with LED bulbs and the like), so we're chuffed about that.

Martyn1981

Hiya Alan. This rings bells from a few years ago on another forum.

I seem to remember that wet/damp panels could do this in some cases, especially if connected to the consumer unit via a 30mA earth.

The solution if I remember was to make sure they were connected on the 100mA side of the CU if you have a choice (or via a 100mA).

I hope this makes more sense to you, than me. The numbers are in my head, but the understanding/explanation isn't.

Mart.

Edit: could be many reasons for the trips, but here are some threads I found on the subject including comments/discussions from PV installers:

http://www.navitron.org.uk/forum/index.php/topic,16318.0.html

http://www.navitron.org.uk/forum/index.php/topic,19046.0.html

http://www.navitron.org.uk/forum/index.php/topic,20332.0.html

http://www.navitron.org.uk/forum/index.php/topic,14792.0.html

http://www.navitron.org.uk/forum/index.php/topic,23073.0.html

Dave_Fowler

Alan_Brown wrote: »

Does anyone have this problem? When it rains our panels trip the RCD which is a major pain because I then have to turn off the panels via the DC switch to avert the wrath of the missus. We had the panels fitted in January and they seem to have always done this.

The solar company who fitted our panels said that we should probably have them on their own RCBO instead of the main consumer unit. Would this fix it?

Incidentally, even though its just been installed since January, our power tracker shows a dip in our electricity usage for Jan & Feb for the first time in years (it has been steadily and gradually increasing, despite my best efforts with LED bulbs and the like), so we're chuffed about that.

Putting the panels on their own RCBO would solve the problem of them tripping out the whole house, but they should not have a problem caused by rain in the first place.

If switching off the panels at the DC switch stops the tripping, then the 'fault' must be on the DC side - i.e. the panels and their connections before the inverter.

There could be a simple fault that is caused by one of the many connectors behind the panels shorting out to the roof or the metal frame of the panels when it gets wet. The connectors should be weatherproof - perhaps one has not been fitted together properly. Also, it is good practice to suspend the connectors away from the roof tiles and the frame using tie-wraps or similar.

Another possibility - a bit of a long shot - is that the framework on which the panels are mounted is not earthed and the rain causes intermittent connections of the frame to earth. It has been noted on the other forums that a voltage can build up on the frame (a minute leakage from the panels or just pure static electricity). Whilst not having the frame earthed is nothing unusual, an intermittent connection between the frame and earth could cause pulses of power to flow which could, theoretically, cause the RCBO to trip.

Dave F

Ectophile

I have the same problem whenever there's a storm followed by sunshine. It's down to the installer cutting corners and using a 30mA RCD.

Having the solar circuit on it's own RCBO may be enough to fix the problem for you, or it might not.

The instructions for my Power One Aurora inverter say that it should have a 300mA RCD. Presumably the manufacturers are aware of this problem. A 100mA one would most likely be an improvement, especially if it's a time-delayed one.

EricMears

I wouldn't consider it acceptable for Solar Panels to be tripping out on a regular basis and would suggest anyone so affected complains to their installer. Don't be fobbed off with "you should have asked for a better RCD" : they were selling you their professional expertise and should have realised their error(s).

Martyn1981

EricMears wrote: »

I wouldn't consider it acceptable for Solar Panels to be tripping out on a regular basis and would suggest anyone so affected complains to their installer. Don't be fobbed off with "you should have asked for a better RCD" : they were selling you their professional expertise and should have realised their error(s).

Absolutely.

If you read some of those Navitron threads, the installers on there (when referring to SMA inverters) state that the installation instructions require 100mA, not 30mA.

And Ectophile states 300mA for his inverter.

The installers should be following the manufacturers instructions.

Edit: And another thread started just yesterday:-

http://www.navitron.org.uk/forum/index.php/topic,26640.0/topicseen.html

Mart.

Dave_Fowler

The OP states that the tripping occurs when it rains.

I think the point that the tripping only happens when it rains is a point well worth investigating. If the tripping only happens when it rains then that is where the investigation should begin.

Whilst it is true that the RCB should rated above 30mA (i.e. 100mA or 300mA) for most inverters the tripping point will not vary with the weather.

Dave F

Martyn1981

Hiya Dave, I seem to recall that many of these issues happen during damp conditions. Is there some way that the panels would suffer earth leakage in wet conditions that wouldn't occur in dry conditions?

As you can tell I'm quite curious.

Mart.

Dave_Fowler

Martyn1981 wrote: »

Hiya Dave, I seem to recall that many of these issues happen during damp conditions. Is there some way that the panels would suffer earth leakage in wet conditions that wouldn't occur in dry conditions?

As you can tell I'm quite curious.

Mart.

Hi Mart,

The solar panels and connectors are usually rated as at least IP65 - most are IP67 - which means both the panels and connectors should withstand a high pressure jet of water applied to them from any direction without any harmful effect.

For rain to be a problem I believe there must be an insulation problem - probably a badly made or fastened connector behind the panels or perhaps a cut in the cable due to bad handling during panel installation.

Dave F

Alan_Brown

Thanks all for the feedback. I'll get in touch with the solar company that did the install. I'm going to get them to install a solar immersion device anyway, so will get them to sort out the tripping at the same time. The electrician attached to the solar company said that my consumer unit was a bit dated and the configuration a bit of a mess. I'll see if they're willing to fit a new consumer unit at the same time, and bring all of the various separate boxes (i.e. induction cooker) into a single unit. After several changes to the house, such as the induction hob, shower units, etc. each electrician has left a bit of a dogs dinner behind and I'd like to get this all tidied up and fed from the single consumer unit.

EricMears

Alan_Brown wrote: »

I'd like to get this all tidied up and fed from the single consumer unit.

There's a lot to be said for having a dedicated isolator with its own RCD to feed the solar panel installation. Live feed to that could either come directly from meter or the CU (but only if you have a split load CU). Having two separate RCDs in series is always likely to cause problems.

No reason at all why the SP contractor shouldn't be asked to undertake the rest of the work (or at least tender for it).