Generation meter failure

baldrick69

I had Solar Direct Savings do an installation in February. All working well until the fuse in the house tripped. A whole weekend of testing later and it seems to be the generation meter itself that is causing the fuse to trip. Solar Direct Savings have just gone into administration.

I can get a replacement from the manufacturers or get an electrician to handle it but either way it seems that I'll lose the current meter reading.

Any advice?

zeupater

Hi

Initial thought based on what I would do ....

Do you have details of the readings from the inverter and TGM at various points in time ? - if so you will have evidence of the relative accuracy and should be able to convince your FiT partner to base the TGM reading at point of failure on the inverter reading then have them reset the reading for the new TGM when installed ...

HTH
Z

Fruit_and_Nut_Case

baldrick69 wrote: »

Any advice?

Don't panic. Some/many/most/all (delete as applicable) modern generation meters have solid state memories which can be interrogated by someone who has the correct equipment. You may be able to retrieve the readings. Possibly try the manufacturer for help.

Martyn1981

baldrick69 wrote: »

I had Solar Direct Savings do an installation in February. All working well until the fuse in the house tripped. A whole weekend of testing later and it seems to be the generation meter itself that is causing the fuse to trip. Solar Direct Savings have just gone into administration.

Any advice?

Just for clarification baldrick, are you saying there is a fault with the meter causing the PV fuse in the consumer unit to trip, or is the CU main trip going, due to the input from the PV system?

Are you certain it's the meter, not the PV system itself? Apologies for being difficult, but I wasn't sure if you saying that the TGM itself is faulty/failed.

What size system is it?

Mart.

baldrick69

@zeupater - Thanks, I hadn't thought of that. Given that there is currently no power to the inverter, I can't tell.

@Fruit and Nut Case - Thanks, I'll try that.

@Martyn1981 - I find it difficult to believe that a newish meter (installed Feb 2012), good make - Landis & Gyr, which hasn't been tinkered with since installation could actually cause the fuse to trip. However, there is an isolator either side of the meter (only the meter is between the isolators). If the isolator after the meter is off then it can't be anything downstream causing the problem, and the fuse trips as soon as the isolator before the meter is switched on. So I'm concluding that it is the meter.

rogerblack

baldrick69 wrote: »

I find it difficult to believe that a newish meter (installed Feb 2012), good make - Landis & Gyr, which hasn't been tinkered with since installation could actually cause the fuse to trip. However, there is an isolator either side of the meter (only the meter is between the isolators). If the isolator after the meter is off then it can't be anything downstream causing the problem, and the fuse trips as soon as the isolator before the meter is switched on. So I'm concluding that it is the meter.

Do you mean a RCCD, a fuse, or a simple overcurrent breaker?

I would return it to the maker, for at least a refund, and ask them to recover the reading.

Martyn1981

baldrick69 wrote: »

@Martyn1981 - I find it difficult to believe that a newish meter (installed Feb 2012), good make - Landis & Gyr, which hasn't been tinkered with since installation could actually cause the fuse to trip. However, there is an isolator either side of the meter (only the meter is between the isolators). If the isolator after the meter is off then it can't be anything downstream causing the problem, and the fuse trips as soon as the isolator before the meter is switched on. So I'm concluding that it is the meter.

Hiya baldrick, apologies if I confuse matters, but I've got an idea that might need ruling out - hopefully those on here with some proper leccy knowledge (unlike me) can help:-

Is there any chance that you have an earth leakage causing your main unit to trip? Apologies for being vague but I've heard a few times that a largish (approx 4kWp) system can leak just enough earth during damp weather to trip a sensitive 30mA earth. The solution seems to be to change/wire the system through a 100mA earth.

Again, sorry if this is a red herring, or total nonsense, but that's why I was asking if the TGM had actually failed, and what your system size was.

Would you like me to try to track down where I read this?

@ Zeup / Roger - you're leccy guys aren't you, does this mean anything to you?

Mart.

baldrick69

@rogerblack - Sorry, we're getting to the limits of my leccy knowledge now. When I say the fuse trips, I mean the 40A RCD in the garage consumer unit.

@Martyn1981 - Thanks, I'll check for an earth leak. Solar installation is a 4kW jobbie.

Another, possible cause is that a 16A RCD (ok, I'll call it another fuse) was also put in by the original installers. This fuse is between the 40A RCD and the first isolator. It doesn't trip - I kinda assumed that being a lower amp rating it would go first - is that expected or a clue??. I'm going try replacing this one tomorrow as it's cheap and might be the cause.

Thanks very much for the suggestions so far.

Martyn1981

Hiya baldrick, found one post, but not the thread I think I'm looking for:-

"As someone with a GTI connected downstream of a type AC RCD shared with other house services, I started looking around for information regarding installation methods, histories of problems, etc. There isn't a huge amount out there, which could be seen as a good thing, or it could be that it's simply not being logged.
I stumbled across BEAMA, who ' provides leadership, expertise and independent influence in the areas of product safety, performance, energy efficiency and sustainability.' They represent a lot of makers of electrical switchgear. They issue a number of guidance docs, including the 'RCD Handbook - December 2010' - here http://www.beama.org.uk/en/publications/guidance-documents.cfm/RCD-handbook-dec-2010. An interesting read. Did you know a typical house wired in T&E will have a 4mA leakage current, and that 30mA RCDs typically trip at 22mA? Your 30mA RCD is now looking a but more sensitive!
Going pack to the original post, in section 9.3 of the handbook there's a piece about how RCDs can trip when items with double pole switches and internal capacitance ie filters, are energised. VDE 0126-1-1 (newer GTIs have this) is a double pole disconnection device. So a GTI turning on every morning tweaks the RCD a tad. And turning off in the evening.

Whilst this cant be the absolute answer, as most of us would be tripping left right and centre every morning, it's a pretty good contributor if you already have an elevated leakage current caused by a bit of damp."

What effect your isolators would have, I'm not sure. Also (if my memory serves me right) these discussions often relate to SMA SB4000TL inverters, something to do with being transformerless. But as mentioned before, I'm way out of my comfort zone here.

If you think this is at all relevant, let me know and I'll find those other discussions.

All the best. Mart.

baldrick69

baldrick69 wrote: »

Another, possible cause is that a 16A RCD (ok, I'll call it another fuse) was also put in by the original installers. This fuse is between the 40A RCD and the first isolator. It doesn't trip - I kinda assumed that being a lower amp rating it would go first - is that expected or a clue??. I'm going try replacing this one tomorrow as it's cheap and might be the cause.

It is actually a 16A MCB (not sure what the difference is). I've replaced it and I've still got the same problem.

Ectophile

MCB = Miniature circuit breaker - detects an overload and trips.

RCD = Residual current device (used to be called an ELCB or earth leakage circuit breaker) - detects current leaking to earth and trips. Does not detect over-current (the current printed on it is just the maximum it can handle).

RCBO = Device that combines an RCD and MCB in one.