Solar PV system fault developed

countryman_2

Hi all,
We had a solar PV generation system fitted on 10th July 2014 by a company from Lancashire. A fault has developed whereby in really bright sunshine the invertor (device which converts DC electricity from the roof panels to AC electricity for domestic use within the home) will shut down displaying a fault code OVR (Over Voltage according to the handbook) this will induce a 30 second restart period and will continue to cycle so long as the sunlight is strong.
I have tried to contact the company which installed the system and they do not answer their phones or messages I leave for them to call back, looking at another thread on here it would appear they have gone out of business.
I contacted the manufacturer (UK distributor/agent) of the Inverter, who were most helpful, emailed me a warranty claim form, the claim was accepted, a replacement inverter dispatched the following day which has been fitted, however the same fault still exists.
I notice that the inverter is rated at 3680 Watts but my system is capable of 4000W and regularly achieves 3800 - 4000+ Watts so it would appear to me that the inverter is not rated enough for the systems maximum output.

I seek your best advice for where I should go next to try to redress the situation please?
Just to add I paid almost half of the cost of installation on my TSB credit card.
Many thanks in anticipation of some good advice.

bris

This isn't a manufacturing issue as the inverter is working as intended.


Your best bet is to seek a resolution from the CC by way of a S75 claim.


Looks like you need a bigger inverter so your claim is the one you have is not fit for purpose.

countryman_2

bris wrote: »

This isn't a manufacturing issue as the inverter is working as intended.


Your best bet is to seek a resolution from the CC by way of a S75 claim.


Looks like you need a bigger inverter so your claim is the one you have is not fit for purpose.

Thanks Bris, that's the answer I was hoping for to be honest, I just wasn't too sure on whether Section 75 claims were more for goods or services not supplied, for example tickets for a show ordered but never arrived etc.

I agree it looks as though the inverter is not fit for purpose and requires one of a higher power rating.

maninthestreet

Have you queried with the manufacturer that the inverter is of insufficient capacity, rather than being faulty?

Martyn1981

countryman wrote: »

Hi all,

I notice that the inverter is rated at 3680 Watts but my system is capable of 4000W and regularly achieves 3800 - 4000+ Watts so it would appear to me that the inverter is not rated enough for the systems maximum output.

Most (almost all) 4kWp systems installed in the UK in the last few years will have 3.68kW capped inverters.

If you want the potential, even theoretical, to export more than 3.68kW (16A @ nominal 230V) then you need prior permission from the DNO first. This may be hard to get.

With PV, the panels can be thought of a little like a battery, with the inverter choosing to take as much as it wants. That way it can cap generation at 3.68kW AC.

Temperature of panels will rapidly drop PV generation down to 90% of kWp rating, so capping on this scale should be minimal, and may be exceeded by extra generation at lower levels by having a slightly smaller inverter.

It's often recommended to undersize an inverter in the UK by 10%.

Moving on to your fault, you could have overvoltage if your inverter and panels haven't been matched properly. For instance running 4kWp of panels through a single input rather than two inputs might exceed voltage rating of inverter. But that fault should happen every time the unit fires up, and have been noticed on first testing.

If you can detail the make and model of your panels, and the inverter, it should be easy to check the voltage of each string, and the max voltage rating of the inverter. Your inverter display, will hopefully tell you what the panel voltage of each string is (DC), as well as the output voltage of the inverter (AC).

Could the overvoltage relate to grid voltage? Later installs should use inverters that shut down if the grid voltage goes to the upper limit of 253V (230V +10%/-6%). One of mine (the newest) did that last year, and I was able to look at one of my older ones, and see that it was still pumping out at 253V. The 'better' inverter came back on when the voltage dropped a bit.

To 'pump' leccy out as export, the inverters need to produce at slightly higher than grid voltage. They should shut down to prevent a spiralling rise when voltage is high. In my case it happened on a Sunday afternoon, when I understand demand is pretty low, so mains voltage can rise.

Mart.

Martyn1981

Martyn1981 wrote: »

If you can detail the make and model of your panels, and the inverter, it should be easy to check the voltage of each string, and the max voltage rating of the inverter. Your inverter display, will hopefully tell you what the panel voltage of each string is (DC), as well as the output voltage of the inverter (AC).

Doh! Just read your outosig.

The Samil 3.68kW inverter has a max DC voltage of 550V. Max DC power rating of 4000W.

SolarWorld 250Wp mono black (not sure if yours are black) have voltage outputs of approx 30 to 40V (pretty normal) so that should mean 2 strings each at around 240 to 320V. This should be displayed on the inverter screen.

Mart.

Martyn1981

countryman wrote: »

I notice that the inverter is rated at 3680 Watts but my system is capable of 4000W and regularly achieves 3800 - 4000+ Watts

Just a thought. Is that a sustained figure, or just a very short spike. If sustained then that might suggest the installer didn't set the cap on the inverter. Or ..... some of the older inverters were capped at 16A (not 3,680W) which if local voltage is higher than 230V would allow a higher figure ........ but this shouldn't happen anymore as inverters should now cap at W's not A's.

Mart.

countryman_2

Thanks for the detailed reply there Martyn1981, I recognise you from the "Generation" thread.

Mine are the Solarworld black 250 panels in two strings of 8 panels.

Yes, these are relatively short spikes in general that I have noticed when watching the display. I've just checked the grid voltage on the inverter and its showing 255v AC, Pv voltage showing 226- 228v and 11.9 - 12.7A, these figures are constantly fluctuating of course.

My overall output remains good with 26.5 Kwh generated yesterday for instance but the inverter cutting out periodically is annoying to say the least as I am tending to avoid putting on high draw appliances at peak generation times now for fear of importing energy to run them.

It's just where to go now for redress as it seems that something is not quite as it should be and the installers are nowhere to be found.

Martyn1981

countryman wrote: »

Thanks for the detailed reply there Martyn1981, I recognise you from the "Generation" thread.

I've just checked the grid voltage on the inverter and its showing 255v AC, Pv voltage showing 226- 228v and 11.9 - 12.7A, these figures are constantly fluctuating of course.

It's just where to go now for redress as it seems that something is not quite as it should be and the installers are nowhere to be found.

Hi CM. Yes it is I Leclerc!

So your DC voltage seems fine, and well within the limits of the inverter. Whilst I'm 99% sure, from the info given, that this is a high grid voltage issue, I have to doubt myself slightly, as I'm amazed that you got a replacement inverter, when it was doing exactly what it is supposed to do?

So if grid voltage is showing as 255V then you've got a problem. Your inverter will/should shut down each time voltage creeps up to 253V+.

You need to contact the DNO and ask them. They have a duty to keep voltage nearer to 230V and between 216 - 253V. However, voltage can rise if demand is low, or there are loads of local SSEGs (small scale electricity generators) in the area, all running at the same time ...... with little demand.

Another issue, looking at your title, is property location. Are you at the end of a long supply line, sometimes that means dialing up the voltage. [Edit: sorry worded that completely wrong, try again. Are you part of a particularly long supply line, as it may have been dialed up to ensure adequate volts at the end, but mean high volts nearer the start. M]

The DNO may (sorry for such a vague may) be able to make some quick changes if there is a transformer or similar nearby that can be altered/upgraded.

A major issue is that despite us having a nominal 230V grid now to bring us closer to the rest of Europe, in reality it's still a hangover from the 240V grid, closing the gap with that dratted 253V figure.

If this keeps happening, then you need to contact the DNO.

Best of luck.

Mart.

bod1467

I though the UK voltage range was actually 240V +6/-10% (216 to 254V)? I know the official specification may be 230V +10/-6% (216 to 253V), but the reality is that no real changes have been made to achieve it, and the specification was a deliberate fudge.

Martyn1981

bod1467 wrote: »

I though the UK voltage range was actually 240V +6/-10% (216 to 254V)? I know the official specification may be 230V +10/-6% (216 to 253V), but the reality is that no real changes have been made to achieve it, and the specification was a deliberate fudge.

The relevant regs are now:

The Electricity Safety, Quality and Continuity Regulations 2002

Section 27 (3) (b)

Mart.