Geograph - photograph every grid square

Part of the Merchiston Campus of Napier University. A note at the base of the bank of solar panels [the right hand part - the left hand is simply 1960s windows] reads 'These solar panels power up to 80 computers in Napier's Jack Kilby Computing Centre. A joint partnership between School of Engineering and Energy Saving Trust. Spring 2005'.
On 3 March 2009 a monitor in the entrance hall of the building recorded that 34.16 MWh of electricity had been generated, presumably since installation, and 20.49 tonnes of CO2 emissions saved.
By 26 August 2011 these figures had increased to 47.46 MWh of electricity generated and 28.48 tonnes of CO2 emissions saved. Over the intervening 2.5 years this seems to be less, pro rata, than might be expected from the earlier figures - I wonder if they have ever been cleaned?
On 14 January 2015 I read the meters again - 66.75 MWh of electricity had now been produced, with a saving of 40.05 tonnes of CO2 emissions. Over the two periods [March 2009-August 2011 and August 2011-January 2015] the average amount generated was 13.9 and 15.5 kWh per day, respectively. With a low sun at mid-morning on a snow-showery January day, the output was varying between 3.3-6.3 kW.
By 19 January 2017 the figures were 78.22 MWh generated and 46.93 tonnes of CO2 emissions saved. Over the period since I first read the meters in March 2009 [just under 7 years ago] the performance has been quite consistent, with an average output of 5.6 MWh/year and a CO2 emissions saving of 3.35 tonnes/year. The output at the time of reading, early afternoon on a dull January day, was only 88.9 watts, which seemed very low.