What can cause an invertor to trip the MCB?

[littlespark]

When visiting my parents, I noticed their PV invertor was showing zero W generated. On inspection, I found the MCB had tripped.
Is there any reason for an invertor to trip it? Powercut, or power surge?
The PV system is rated 3kW, and the MCB is 20A, type C.
We checked back the history on an app, and the mcb apparently tripped on june 11th. They've lost 8 weeks of cheap leccy and FIT.
Any ideas, solar experts?

 

[dmxtothemax]

With out knowing a lot more about your system it's configuration and the loads involved then it's just a shot in the dark.

 

[westward10]

Apart from being faulty only one thing will cause an mcb to trip and that is excessive current.

 

[Wilko]

Hi - are there any generation details from 11/6 ?
Did you reset the mcb and what's happened since?

 

[Leesparkykent]

Deleted....Must read thread properly....Thought inverter had tripped not mcb.

 

[littlespark]

Thanks all for replying...
As stated on OP, its a 3kW system, it cant generate more than that, and readings show its maximum output ever was 2.8.
20A Type C MCB in consumer unit. Supply up to invertor in attic run in 4mm T&E. Dedicated circuit.
There have been no recorded readings on the app since 11/6... After resetting the MCB and waiting a few minutes, it reads normally.
I'm not trained in solar PV, but I know that the invertor will not feed back into the house, if its not picking up mains voltage coming from the house.
I'll keep an eye on the breaker.. if it trips again, there could be a fault with the inverter.. costly replacement, unless its still under warranty.
Are invertors usually installed with a type C MCB? The rest of the house circuits are on a type B?

 

[SolarCity]

We've taken on the maintenance of a lot of systems and seen this a lot. Circuit tests fine, inverter looks fine, inverter log shows nothing unusual. Yet the breaker has tripped out. No signs of any faults at all.

We replace the breaker when we have this issue and ask the customer to keep an eye on it.

 

[SpecialistEnergy]

What brand of inverter is it? There are some pretty cheap pieces of kit out there... Personally I would say that as we know the only thing that will trip an MCB is a short circuit or overload, and if the wiring is fine, the only possible cause is a faulty inverter - assuming the correct MCB was used.

Type B MCB should be OK

Where are your parents based?

 

[littlespark]

Parents are in Scottish borders, same as me.
I don't know the brand offhand, but ill have a look today when I'm visiting.
Their neighbours had said there was a 'surge' on the power. They were on holiday, so didn't witness. I take it the neighbours meant a 'flickering' of the lights or something. No other circuits tripped in the house.

 

[SpecialistEnergy]

You'd have to hope that as an inverters job is to manage and synchronise fluctuating power that it would be protected against this sort of thing, and would continue operating afterwards. But if it is cheap kit then maybe not so good protection on the AC side... You are welcome to PM me with more questions, I specialise in troubleshooting PV systems

 

[littlespark]

thanks for the offer. My dad will keep an eye on the breaker in case it trips again... I can change the mcb to a type b if need be. The invertor is a Solax Power X1. Possibly on the cheap side of decent kit.
On another note. I have been getting phone calls about a bit of kit that can be added to my own solar pv array that can increase the energy by 25%. Pretty dubious, and I always tell them to go get a proper job. I assume there isn't anything out there that can improve the output of the panels?

 

[Wilko]

Do tell - we all love a good miracle, perpetual motion invention etc

 

[SpecialistEnergy]

errr - does it involve firing a nuclear bomb into the sun to make it brighter for a bit ?! Definitely a scam, name and shame!

Cleaning them yearly is more than adequate, and just use your window cleaner as long as they use a pole fed de-ionised system and not soaps - its safer and better for the panels.

Cleaning yearly is worthwhile especially on the higher tariffs from 3-4 years ago, gets a bit less worthwhile on the more recent tariffs but still good practice.

 

[littlespark]

Its when I say "I'm not interested", and they come back with "You're not interested in saving money?" That's when I hang up.
Only one time someone described it as a "chip" thats installed in the system.
Isnt there a way to store the DC in a battery so when the sun goes down, the invertor continues to generate AC for a time?

 

[SpecialistEnergy]

Only one time someone described it as a "chip" thats installed in the system.
Isnt there a way to store the DC in a battery so when the sun goes down, the invertor continues to generate AC for a time?

Yes you can get AC charging or DC battery systems that can either allow you to get use of extra power after sun down, or also give power during a blackout: the second option is more expensive than the first.

They are getting quite cheap (relatively speaking), but a lot of cowboys out there. Won't suit everyone