Let's keep going with this blog while I have the interest.
I knew that the 41.3p FiT would only apply to systems below 4 kWp. I asked why I had been quoted for a 3.5 kWp system when another panel would increase its output further and still be under 4. Turns out that for systems rated over around 3.7 kWp, the electricity company have to carry out a feasibility study to check the cabling can carry the load. This may seriously delay the project and possibly cost heavily. OK. I'll stick with a 3.5 kWp system.
A note on terminology regarding panel ratings. A solar panel will produce electricity when light lands on it. More light, more power. The most power a typical panel can in reality generate will be when it is directly facing a very high Sun through a clear sky. The power then being generated will be its peak power and this is stated as Watts-peak. I've been quoted for twenty panels each of which are rated at 175 Watts-peak, or 175 Wp. Put 20 of these together and the rating of the entire system is 3,500 Wp or 3.5 kWp.
Of course, my system will almost never generate its peak power. It might approach it on the odd fortuitous late-June day. We get a lot of cloud in Scotland. That will be a big drop. Our roof pitch at the back of the house faces 20 degrees south of due west so will generate most electricity in the afternoon and will miss much of the morning sunshine. That's another drop. According to what I've read or heard, our location will cost 10% compared to the UK average. Our house's orientation will cost another 10%. Therefore, from government tables, we can expect to generate 2,900 units of power annually. It will be very interesting to see if reality matches the predictions. I can't wait to start taking daily measurements.