Solar tripped MCB

[monkey5]

Evening all, so solar been installed since Oct last year, all been good, been out today and had an alarm flag up on the app. couldn't get it to refresh and tell me any figures.
Anyway come and search for the fault to try to clear, turns out the 20A MCB had tripped. Not sure why, any ideas what might have caused it, and it wasn't at the height of the day when we were generating the most and battery temps looked OK.
Cheers

 

[Fleeting]

What caused it to trip, overcurrent or fault current.

 

[binky]

It happens sometimes, one of my installations trips once a year for no discernable reason.

Reset the MCB and see what happens, it maybe a faulty MCB, it maybe a marginal sized AC cable size/ MCB. What inverter do you have?

 

[monkey5]

It resets fine, but was after a few hours as was out when it happened. 20a MCB, solis 6kw (SOL-6K-RHI￾48ES-5G-DC). So it at 1545, carried on charging the battery until that was 100% but obviously didn't send anything to grid or use for the house draw. A working fine so maybe just a blip, just wondered if anyone knew if there was anyway of looking at different figures at the time rather than just the graph or any other ideas why it could have tripped.

 

[binky]

6kw is 24amps, you can double check max inverter output on the spec sheet. So I'm not too surprised the MCB has tripped, they will take an overcurrent for a while, but not ad infinitum.

 

[monkey5]

Cheers binky , but where has the 6kw come from? It was generating less than 15A for 25 mins up to the alarm and trip.

 

[monkey5]

I don't do solar and didn't install myself, juet enjoy it when it's generating and able to use little from the grid.

 

[binky]

Cheers binky , but where has the 6kw come from? It was generating less than 15A for 25 mins up to the alarm and trip.

Err, you just told us you have a 6kw inverter

 

[monkey5]

Yes but what I mean is that at the time 6kw wasn't being drawn for the MCB to trip. I could understandi it, if I was charging the battery up by 6kw from the grid but the slar was generating and sending direct to battery.
So can the MCB detect overcurrent the "wrong" way through it if I was sending over 6kw straight from solar to house circuits?

 

[binky]

So can the MCB detect overcurrent the "wrong" way through it if I was sending over 6kw straight from solar to house circuits?

Wouldn't be much use if they didn't, think electromechanical fuse wire...

 

[monkey5]

I've been thinking about it since i wrote it and sort of answered it my self.
So I'm now thinking the 20A MCB isn't ideal due to this scenario, sunny day, solar kicking out 6kW, batteries full and house drawing over 6kw, gonna get a tripped MCB. Time to revise I think.

 

[binky]

What size cable have you installed?

 

[monkey5]

6mm, 7m max so easy enough to higher MCB. Just never really thought about it, but obviously the trip has high lighted the problem

 

[binky]

6mm, 7m max so easy enough to higher MCB. Just never really thought about it, but obviously the trip has high lighted the problem

Change to a 32 or 40 amp with that cable.

 

[yozhughes170]

When my Growatt 6Kw system was installed it had a 16amp that kept tripping, the Solar Co sent someone out who changed it for a 32a. Different electrician, and now a year later still no more tripping