grahamsmythe

I was one of the early solar adopters with the FIT scheme. I think I've still got about ten years left to run, and it's been a great source of income for us. With the huge rise in electricity costs, I've decided to get some more panels installed. A local company has given me a quote on the basis that they'll leave the existing installation alone so it won't interfere with my FIT payments. This new installation will be completely separate. I've been quoted £10,500 for 20x410 Watt JA Mono Crystalline Panels, 1 x Solis Inverter, Roof mountings, DC cable, Generation meter and isolation switches. I've decided against any batteries for the time being, as I'd like to see what MyEnergi come out with towards the end of the year before I jump in any particular direction. To summarise - 8.20kW for £10,500. Reasonable?

How should a DC Inverter be protected in a Consumer Unit? Currently our inverter has a 16amp MCB on the non-RCD side of our Consumer Unit. 1. Should it be moved over onto the RCD side? 2. Should the MCB be replaced with an RCBO? Would the electricity flowing the opposite way cause an RCBO to behave differently? 3. Should it just stay as it is? Any suggestions would be gratefully received.

Yes, I'll try to do that once I've finished it.

Thanks gents. Much appreciated. I did change the wiring on the isolator in the loft, but as mentioned by @ProDave I now only have one isolator for DC isolation, so I'll get another DC isolator to do it properly. My multi-meter goes up to 1000v DC so was able to prove it was dead. However, I did take the precaution of doing the work at night!

Is it safer to do all the connections etc at night? ?

So, just to be clear, am I right in thinking: 1. Switch the DC isolator in the loft to off. 2. Switch the DC isolator in the garage to off. 3. Isolate the AC isolator in the garage to off. 4. Unplug the wire that goes from the loft isolator to the panel (x4). I'm then safe to alter the wiring as described previously?

This is the specification of the panels…

The panels are 195w (20x195w = 3.9kw). The inverter is a Diehl AKO Patinum 4300S http://www.raine-or-shine.com/dloads/PV/Inverters/Diehl-AKO-Platinum-Inverter-Manual.pdf

Some time ago, we had a PV system installed, and ever since, I've been unhappy with the way it's been wired, so would appreciate any thoughts that you may have. All DC wiring is 4mm. As you will see from the image below, we have two strings of ten panels, and these are connected together via a DC isolator in the loft. When the cable exits the loft isolator, both positive and negative go down into the garage via four 4mm cables. When the cables reach the garage, they go through another DC isolator before exiting through a single cable and then into the inverter. Currently all works fine. However, our inverter has two sets of inputs to facilitate two strings, so what I'd really like to do is take each string down to the garage separately, so we're able to connect the two strings separately into the inverter, so we can see how the strings are performing individually. The following diagram shows how I think it could be done using the existing wiring and isolators. As stated previously, I'd appreciate any thoughts that you may have.