Solar PV system question

Hi All,

I'm seeking some advice about a solar PV system we had installed in November 2014 please. I would take it back to the contractor, but they've ceased trading, and it turns out that they never provided our details to the so-called insurance backed guarantee firm. That means we're tucked up a treat, but still paying for the privilege.

They installed a 4kW system comprising 16 off 250W Canadian Solar panels. After 18 months, we seem to be consistently short of the predicted generation figures. That's when I discovered the installer had gone bust. The array is connected to an inverter made by SAJ, who've been quite helpful so far.They tell me the inverter is rated at 3kW, and that regardless of how much power the panels produce, the inverter will cap the output at 3kW. Is it normal practice to install a lower rated inverter than the max power that the panels could produce? Is that likely to be the reason our generation seems lower than we expected, or could it be a duff panel? And perhaps most important, is it safe?

As far as I can tell, the output from the inverter is linked straight into a ring main. Is that good practice? The inverter log has collected a lot of error messages most of which are grid or isolation related. While SAJ say they'll help interpret those, is the way the system's connected to our mains a possible contributing factor to these errors?

The only good news is that the finance provider says we can make a Section 75 claim to get it put right, if indeed it's wrong.

I'll be really grateful for any advice.

Many thanks in advance

Mark

 

Thank you for all your replies. I was trying to convince myself that it was just the changes to the FIT scheme that made trading too difficult for the installer, but it sounds as though we were well and truly had
I guess alarm bells were ringing from Day 1. Their sales pitch said that they'd erect a scaffold. When they booked the job, they said the scaffolders would be in the day before. We rang them to say no one turned up, but they said it was all in hand. On the day, the installers turned up with a couple of ladders... My wife says their electrician spent only about 30 minutes here, and a big chunk of that time he was filling in an inspection report!

Stugadget - Our CU has a number of spare ways on it, so they could have run a separate circuit back, but that would have involved laying cable all the way to the other end of the building! Since my original post I've traced their wiring. They brought a 2.5mm cable out from the inverter into a separate MCB on the shower CU. That's fed from the main CU by a 10mm cable, which sounds like overkill until I tell you it's a 10.8kW shower. On a sunny day, there's a steady red light on the main meter, which means we're generating more than we're using, but overall, we're about 8% lower than predicted. It's not huge, and I suppose it could be simply that it hasn't been the best summer so far. Perhaps another factor is that the roof faces southwest, and it's a very shallow pitch at 22.5 degrees, but surely that should have been taken into account in the original calculation? We're tucked away down in the southeast in Hythe, Kent.

HandyAndy - The installation was financed through Barclays Partner Finance. I've been in touch, and they've already logged it as a potential Section 75 claim, whatever that is. They asked me to first ascertain whether there was any insurance, which seemed fair. It turns out that it was never logged with the insurance company, so it's back to Barclays. In fairness, they said they'll help me resolve the issue and that's one reason why I'm keen to gain as much insight as I can. My guess is that it will be a once only shot. If the panels are working OK and it just needs an uprated inverter, that might be the lowest cost solution for them. We're getting FIT payments and a fair amount of 'free' electricity, just not as much as we'd expected. On that basis, a reduction rather than a write off would be fair, although I won't complain if they decide to write it off.

DA - That's a very useful link and I'll follow up there too, thank you. I agree that it sounds nuts, and that's what made me ask here. I'm glad it wasn't just me! I'll report back in due course with any more info.

I've done some background checks and as far as I can see the installer has genuinely ceased trading. There's no sign yet of the directors popping up anywhere else; having said that, they only went down the tubes in April this year. If they reappear in this sector I may start asking some awkward questions very publicly.

Thank you all again for your comments and advice

Mark

 

All,

Reading back my last reply, I see I missed one other thing. The installers put the inverter in the loft. I'm not sure whether that's standard practice, but it seems odd given that the manufacturer gives very clear instructions about the importance of air circulation around the device. There's a whopping big heatsink on the back, which tells me that it generates heat as it converts DC into AC. The shallow pitch on our roof means there's not much space up there, and it gets unbearably hot in summer. Does that mean the inverter is under even greater stress?

Thanks again gents

Mark

 

Hi Stuart

Thank you again for your advice. I'm a little confused because the pre-sales estimate was 4020kW per year, which falls in between your two figures. Perhaps that's another sign they misled us.

In actual performance terms we're seeing better than your estimate. We produced 3786kWh in the past year, which is 6% down on the sales prediction. In the last 30 days we produced 482kWh. Here's a summary in more detail: -


So, am I right in thinking we're actually doing better than we should be, given the constraints of the inverter, but not as well as we could be if a correctly rated unit had been installed? We're definitely down on what we expected.

On your other points, there is a lockable isolator next to the generation meter, which is where they tapped into the shower CU, and there's a label by the main CU to alert anyone that there is a Solar PV installation. The shower circuit is protected by a 50A MCB and labeled "Shower/SolarPV". There are secondary MCBs in the shower CU, one for the shower & one for the Solar PV. The electrician gave us a NAPIT Electrical Certificate and a circuit diagram, and we have an MCS certificate, but I'm still uncertain whether the circuit was compromised by the addition of the Solar PV.

There's no sign that they told the DNO. If I understand that term correctly, would that be UK Power Networks in my area? Should I advise them of the installation?

SAJ tell me there's a networking facility on their inverter, which would make interrogating it simpler. It's a long way from my router so they're sending me details of how to connect via wifi. They seem very responsive and keen to help at the moment, but as you say, that may change if the unit fails because it's underrated.

Thank you again

Mark