The end of 2016 marks the end of the first full calendar year of solar PV operation in this house since the system was installed in late September 2015. In 2016 we’ve generated 4,129 kWh – 12.5% more than the 3,668 kWh annual output estimated for the system.
Income for 4,129 kWh generation with 50% deemed export is £641, with further savings made from the self-use of the electricity rather buying electricity or gas. Detailed monitoring of these savings only started in March 2016, so there’s less than a full year of data, and my ability to use generated electricity improved through the year – particularly with my electric car charger control project. From March to December 2016 we used 44% of the generated electricity replacing bought electricity, and a further 28% of the generated electricity replaced bought gas for hot water. Back in September at the anniversary of the solar PV installation I estimated these energy savings as a combined £200 (link).
The chart above shows the minimum, mean and maximum daily generation for each calendar month since installation.
As one might expect, significant seasonal variation is evident month-to-month and well as day-to-day variation within any month. June 2016 looks a bit disappointing compared to May and July. The last few days of September 2015 immediately after the panels were installed were obviously quite good for September, but within the spread for September 2016. October looks quite similar for 2015 and 2016, while November 2016 is rather better than November 2015. December again looks quite similar for both years.
Solar panel power outputs deteriorate with time. My panels are supposed to have at least 90% of the original minimum power output after 10 years, and 80% after 25 years. Generally mine seem to be performing well with annual generation significantly higher than estimated, and no evidence of performance deterioration in the late September to end of December period for which 2 years of data exists.