Help! Solar Pv System Question

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Hello All,

I'm seeking some advice about a solar PV system we had installed in November 2014 please. After 18 months, we seem to be consistently short of the predicted generation figures. I tried taking 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 of owning a possibly dodgy system.

They installed a 4kW system comprising 16 off 250W Canadian Solar CS6P-250M panels. The roof pitch is only 22.5 degrees, and we're in southeast England (Hythe, Kent). The array is in a single plane facing WSW, and it's connected to a SunUno TL3KB inverter from SAJ, who've been very 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? I assume the array can generate more than 3kW on a sunny day. Will that damage the inverter? And perhaps most importantly, is it safe?

The inverter is in the loft, where it's connected to the panel outputs via two isolators. The inverter output is a 2.5mm T&E cable that runs to the airing cupboard, where there's another isolator. That's wired to a 16A MCB which was added into the Shower consumer unit. The shower CU contains a 63A RCCD main switch, and is fed by a 10mm cable from a 50A MBC in the main CU at the other end of the house. There is clear labelling on both CUs. Is that good practice and is it safe? Incidentally, the shower itself is a 10.8kW affair on a 45A MCB in the shower CU.

There are a lot of errors in the inverter log has collected a lot of error messages most of which are grid (codes 02 & 11) or isolation (code 10). While SAJ say they'll help interpret those, is the way the system's connected up a possible contributing factor to these errors? Could it be a function of the array producing too much power for the inverter?

Here's a table with what we've actually generated. The system seems to be working, just not as well as predicted. We're consistently 6% down on the pre-sales estimate. Would an adequately sized inverter correct that?

I'm sorry to arrive here as a newbie with all these questions. I know a little about electrics (qualified to the 16th years ago and then never used it...), but nothing about solar. I'm keen to find out as much as I can because there is one glimmer of light; our 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

Thats why I got out if it. Too many cowboys came in and ripped people off, yet MCS who were supposedly there as the installation police did bugger all. Your panels are fine, its your inverter that has not been matched to it. If it was installed at the peak when you couldnt get kit for love or money then chances are they have installed what they could grab hold of. Get in touch with MCS they are supposed to be the ones who oversaw all of this. Who was it registered with Napit or NICEIC? Get onto them too.