In April 2013, I went 'solar" with a 9.9 kW array of 41 240/245W Silfab solar panels installed with SolarEdge module optimisers and connected to two SolarEdge inverters, for a cost before tax of C$44K. The system was eligible for Ontario's microFIT program where I am treated as a power generator and paid C$0.549/kWh for twenty years, while still being charged for any energy that I consume.
Based on the slope of my roof and trees that might block the sun, the installer estimated the panels would produce 12,850 kWh per year - the equivalent of 3.5 hours of full production per day. Unfortunately, actual yearly production has been 10,258 kWh/year, about 20% less than the estimate.
The graph shows that the panels produce within 5-8% of estimate in May through September but fall short by 52-64% in December through January - even a centimeter of snow effectively shuts down the panels. The installer claimed the snow would slide off, but unfortunately that only happens if the air temperature rises above 4C on a sunny day. In the winter of 20213-2014, the snow and ice became so heavy that the panels started to bend. Since then, I have been clearing the panels with a snow rake, a somewhat risky procedure that only makes sense if the forecast shows an extended period of sunshine.
The good news is that the panels have performed reasonably consistently, delivering 73-86% of estimate (the first bar above) without any clear trend that the panels are declining in efficiency. Panels 1.1.4 and 1.1.8 at the left of the first image are shaded by the middle roof section, while panels 2.1.6/12/18 on the right were shaded in 2017 when a sunroom was added.
The solar array has had very few issues. One module optimiser failed in late 2014 and was replaced under warranty. The shaded panels are reporting "module voltage mismatch" which SolarEdge claims is a panel issue which the panel manufacturer denies. I can have the panels removed and shipped at my cost to/from the manufacturer for testing. but I am going to wait until panel production is clearly affected. One of the inverters would not wake up from 'night mode' on September 12th but I was able to recover it a few days later by power-cycling the inverter.
The solar array was fully financed by a Home Equity Line of Credit with all income earned applied to the loan. I had estimated it would take eight years to pay off the loan, but the lower energy production meant that the loan was not paid off until August 2023.
So far, the solar array has generated 104mWh while my house (and the electric car in the last three years) used 66kWh with a net contribution to the grid of 38mWh. I have not done the calculations but that helps offset my vacation travel carbon emissions.
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