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

 

[Wilko]

One idea is to charge a local battery using power that can't be exported and use that to run the invertor when the sun has backed off. This could work, but be careful of claimed return on investment

Edit - oops SpecialistEnergy beat me

 

[Gary K]

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?[/QUOTE]

Was it PV+?
There is a thread about it on the main forum page.

 

[SpecialistEnergy]

They might be talking about optimisers - but they won't increase the performance by 25%. Unless there are several panels in shade. Its a pretty expensive thing to do as it involves putting a unit on each panel with shading issues, plus usually some kind of internet gateway. So scaffolding plus optimisers (£40-50 each) plus gateway plus labour plus markup.... £2000 - 2500 for a domestic system? Might be worth it, but you are left with optimisers on the roof which may fail in the future so you'd have to think carefully about the pros and cons

 

[littlespark]

PV+? I dunno.. I never get far enough into the conversation to find out who they are, or what they're selling... but ill have a read, cheers

 

[littlespark]

Mines is south facing roof, zero shade. I think I can get as best as I can get in way of returns. Mine been installed 6 years now, so decent FIT too.

 

[The Solar King]

There is alot of dodgy mis-selling of SolarEdge going on. It is currently unclear how the protagonists got hold of the names and addresses of people with PV installed. there is a suggrstion that the MCS database may have been hacked. The selling practices are dreadful. Most of the companies involved are not members of RECC and some are not MCS approved installers.

Other companies have been tempted to jump on this band wagon, some of whom should know better.

Only time to ever concider this is when your inverter fails. Even then, unless there are serious issues over shading etc, you would be unlikely to ever make your money back.

SolarEdge is absolutely brilliant kit when used in the right way and installed at the right time. If you want to know how good, just loook at the number of installers and industry professionals have it on their own properties.

The shysters will soon move on to battery storage where the opportunities to mis-sell will be legion.

 

[Gavin A]

I'm pretty sure that the databases used were simply built up by the previous cold calling companies who were selling solar who simply recorded every time the person answering the phone told them they weren't interested because they already had a solar system installed.

 

[Electrical]

Such cases result from power surges. I can't guess anything other than that.