The first year of operations for our 95-panel, 34.7 kW rooftop solar system was very successful. The short story is solar production was almost exactly what our vendor, Clean Energy USA, had predicted – 37,900 kWh, which is 25% of our electricity consumption. Aside from the obvious benefit to the environment we did save some money, but the exact amount is very hard to pin down because of changing Delmarva Power rates and variation in our year-to-year usage. An estimate is $4,500 plus $1,600 from selling solar renewable energy credits (SRECs) via the state-run auction system.

The 2 graphics available at this link provide some more details. Our bar chart dramatically displays the changes in solar production wrought by day length and sun angle while the table tells you all you need to know about our usage and the split between solar generation and what Delmarva Power provides. Another interesting tidbit that further illustrates the tremendous variation in the amount of sunlight falling on our panels during the daylight hours: the peak output* of the panels varied between 0.16 kW on a snow day in February and 28.8 kW several times in April through August, while daily production** varied between 0.39 kWh on that snow day and 203.07 kWh on a long day in June.

So far in 2023, we are producing about 15% less than last year because there has been more cloud cover; let’s hope for more sun in the coming days!

– Bill Hardham for the Solar Team