Kostal Piko inverter - tripping RCD

[SolarCity]

Hopefully I can get some information on a problem I am having at one of our installations.

We are getting nuisance tripping on our PV system: 3.75kWp system with a Kostal Piko 3.6 inverter.

TT system, connected via it's own 100mA RCD. Every now and then, it will take the RCD out. My tests are all good so I'm at a loss to work out what is going wrong.

Kostal Piko's technical helpline is great if you like listening to 'soothing' music with intermittent interruptions to inform you that the line is busy in both German and English. After 45 minutes it does get a bit irritating.

 

[powervan]

u no ur stuff!! so i would think only thing to do is swop rcd with another make and HOPE!

 

[SolarCity]

We'll try that but I'm interested to know if any other installers have had similar issues and then sorted them?

If we were getting very rare tripping then I'd say that changing the RCD may be the answer - as it is, it is quite common and I'm thinking that it may be something about the inverter which the RCD doesn't like. 100mA is a lot of earth leakage.

 

[powervan]

existing house rcd (modern and tests ok) ie no tripping?

 

[powervan]

we once had a prob (not solar) where the old rcd from shed/garage to rod conflicted with the new rcd/rod we put in for the hse?

 

[SolarCity]

Yeah, no problems on the existing installation.

 

[Von Vardo]

I'd be interested to know if you find a solution. I have a Pico 3.6 to install tomorrow, also on a TT system.
I thought the inverter has a 30mA RCD built in?

 

[JulianC]

Apologies as I'm sure you know all this already but hey-ho.....

Are you saying the PV is on its own RCD, separate to the rest of the installation? If so, and your wiring's OK, it can only be a duff RCD or a duff inverter. RCD is cheapest so swap that first.

If it's a shared RCD, then it's most likely an accumulation of leakage throughout the installation, tipped over the edge by the addition of the inverter. Usual suspects are kettle, fridge, iron etc.

What's a ramp test show the RCD trip at? I've had brand new 30mA RCBOs regularly trip at 15mA before now....

Just out of interest, what happens if you disconnect the array frame bonding?

 

[moggy1968]

interested to know as I also have one booked for a TT system

 

[powervan]

kostal piko translates into (never again

 

[SolarCity]

The RCD is seperate to the rest of the installation. We had it originally on a 30mA RCD while we waited for the 100mA to arrive. It tripped out a couple of times on the 30mA but this didn't concern me too much. Taking out the 100mA is a bit more concerning. Repeated ramp tests suggest that the RCD is ok but we will maybe change it for a different manufacturer and see what we get.

Disconnecting the array bonding is my thought also. Our insulation resistance tests suggest that we should have no problems but it is definitely something we will look at. I had been pondering the possibility that a short circuit from the panels onto the frame could take the RCD out but I'm not sure if this would happen.

 

[The Solar King]

Interesting to note that Power-One call for 300ma RCD on their TLs

 

[d8189661]

No longer tripping at the moment and the sun is out.

Great Install, Professional Team, well done.

 

[d8189661]

Another 6 kWh produced again today. Terrific install guys.

Have a good holiday lads and look forward to seeing you soon.

Kev

 

[Von Vardo]

I installed on a 30mA rcd - It's been installed for 2 weeks and hasn't tripped yet. What make of rcd were you using?