Proof of the pudding

On paper the system looked impressive but our interest was in how much power it would generate in practice. Every location is different so there is no sure way to predict just how well it is going to work. The PVGIS site has a modeller that allows you to get a prediction of what sort of power your system should generate. Comparing the power your system generates against these predictions is a good way to see how well your system is doing.

Our system was installed on the 20 September so we only had 10 days of data for September to look at. The prediction for the whole of September was 338kWh so one third of that would be 112kWh, in fact we managed to generate 145kWh which was a very encouraging start. We have just had our first full month of data for October. The prediction was that we would generate 217kWh, in practice we managed an impressive 307kWh. This was over 40% more than expected. I think that we were lucky in that the weather for the last 10 days of September and the first three weeks of October was unusually sunny, we will have to see how we get on in the coming months. The last week of October was rather cloudy and the first week of November has continued in a similar vein so we may struggle to do as well this month. I will report on how we did in early December.