Solar on a Strata – 2015 Summary

Note: This is another entry in the ‘Solar on a Strata’ blog series. 

This chart summarises electricity output for each month of 2015, starting with when we turned on the system June 11. 

The blue bars show how much electricity the ‘pvwatts’ website from the National Renewable Energy Laboratory predicted we would produce, and the green bars show how much we actually produced, as reported by the Fronius inverter in spreadsheets mailed from the Fronius website each week and month (the inverter reports on AC actually going into the grid, after internal losses). Our very sunny summer – especially June and July – started out with much more than predicted, and the rest of the year was about even. 

In all, I’m impressed with the accuracy of pvwatts, and pleased that it was a bit conservative, meaning that so far we have produced a bit more electricity than promised. 

pvwatts uses sunshine recorded by Environment Canada at Victoria International Airport for its predictions. There are now many more weather stations around Vancouver Island in the School Based Weather Network, and all of their data is available to download, including solar insolation – sunshine in watts per square metre which is the standard measure of sunlight intensity. Perhaps someday pvwatts will start using their data and we will have slightly more accurate predictions for solar PV generation around the CRD and even north on Vancouver Island. But for now, I’m happy with our results. 

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