Year three's ups and downs

I'm astonished that the third year of solar generation has been completed. I have another fistful of numbers with which to contemplate and compare the generation of electrical power in cloudy West Central Scotland. I'm really pleased to have continued logging my power generation faithfully for over a thousand days and I've no thought of stopping. It's too interesting. So how was 2013/13?

Well, it was almost exactly the same as the year before, beating it by a mere 16.2 units at 2,414.2 kilowatt-hours of electricity generated. Compare this with year 1 which was better by nearly 200 units. Also compare it with the predicted generation figure, 2,480 units, that was given to me by the Installation Company. Actually, if you average across the three years, actual generation has been almost identical to the predicted value.

A favourite method I have of visualising and comparing each year is to graph out the accumulated generation:

You can see how a 200-unit offset between the first (blue line) and subsequent years really came about thanks to a good autumn that we must have had in 2010 (or maybe two rotten autumns in 2011 and 2012). Year 3 is indicated by the yellow curve and you can see that towards the latter part of the year, a sunny April was beginning to close the gap on year 1. Then there's a sudden kink that takes the line back towards that for year 2. This kink coincides with 2 May 2013, which just happened to be the day my son, Kevin, had chosen to begin a bid to climb all of Scotland's Munros in 100 days. (There are 282 Munros, Scottish mountains over 3,000 feet height so it is a considerable challenge.) He immediately got hammered by wind, rain, hail and snow; and my panels suddenly saw little light.

A new green-coloured line that represents year 4 is beginning to show on the left but it's too early to determine any trend. However, one week into the year, the panels recorded their highest ever single day's generation figure of 22.4 kWh and we're still a month away from the summer solstice. The next nearest figure came on 17 June 2010 when the panels were a month old and that was only a few days from midsummer. This gives me reason to believe that the panels are showing few signs of deterioration.

In summary, the panels are doing exactly what was expected of them and I'm very happy and settled with the return thus far. What is interesting to see is that having a set of panels adorning the roof is no longer unusual. I see them all the time now. Despite the huge fall in payments for generation, interest is obviously still high, helped no doubt by the rising price for retail electricity and the plummeting cost of panel installation.

On another connected note, my liking for environmental toys has been tickled by the purchase of a hybrid car; a Toyota Yaris T4 Hybrid. As I have always done, every drop of fuel that goes into the tank and every mile travelled with be dutifully logged and entered into a spreadsheet to see if real figures match my expectations and the manufacturer's claims.