System Background

The arrays face south-east and south-west respectively. The system has a rated capacity of approximately 5.9 kWp - this being the maximum instantaneous output under  ideal conditions.

The system was made possible thanks to the former Low Carbon Buildings Programme (Phase 2) and generous grant funding from the ScottishPower Green Energy Trust.

The predicted energy yield of the system, based on known panel performance and orientation, was 5,036 kWh per year - a specific output of 856 kWh/kWp. The PV system reached that milestone more than 3 months ahead of schedule in its first year, and has now comfortably exceeded it in both full years of operation. Specific output of 950 kWh/kWp was achieved in year 1, and an even better 952 kWh/kWp in year 2.

Output Monitoring

Performance over this spring and summer has been disappointing, in line with the very unsettled weather. Total output is about 10% behind where it was in the previous 2 years, but there's still time to catch up as the weather improves. Typical year-to-year variations can be up to 15%, so the overall tight consistency in our first two yearly totals is perhaps coincidental. In terms of high-output weeks, it is notable that 2011 yielded only one week with output above 200 kWh; in 2010, there were 4 such weeks, and in 2012, there has been just one.