Solar Performance - August 2014

Production in August was down from July, and roughly the same as April. This makes sense given the shorter, cloudier days of late. Use was also down slightly as the cooler temperatures meant I didn't need to run the fans and air conditioning quite as much.

Solar production, grid purchase/sale, and use.

As expected, the system continued to generate a surplus of power for the month. It's on track to have a surplus on an annual basis as well! Unfortunately, panels A13 and A14 were out of commission for the first half of the month until the defective Tigo unit was replaced. Combined with the days they missed last month they are noticeably lower than the rest of the system. Panel A2 is definitely lagging due to the afternoon shading.

Percent of household energy use produced by solar.

Cumulative production by panel (DC).

Production is a bit under the installer's estimate, mainly due to the bad panels, but is still pretty much on target.

Comparison with installer's estimate.

Breaking the data out by day there were only a handful of days that the system wasn't able to generate more power than I needed. Some of these were laundry days (the dryer is a killer!) while others were just very gloomy weather.

Daily solar production, grid purchase/sale, and use.

Percent of household energy use produced by solar.

At the panel level, shading is still having a noticeable effect on panel A2, while the outages on panels A13 and A14 reduced production significantly.

Energy by panel, broken out by day. The lack of output on panel A14 (covering the dots for A13) is very apparent.

Noticeable loss of output on panels A2, A13, and A14.

This demonstrates why I wanted to make this chart: under-performing panels are easy to spot.

Hourly production shows a peak level similar to April but is shifted about an hour later in the day. I should try to find a solar elevation chart to see if this correlates.

Production by hour for the past 6 months.

The financial performance continues to be quite good, with the Renewable Energy Credit (REC) from the state bringing in the majority of the income.

REC payments are dominating the net-metering savings.

Lastly, a few more esoteric graphs.

Total production by panel direction.

Production normalized by the number of panels (8 East, 6 West).

DC to AC conversion efficiency was pretty uniform. I've noticed in the past that it drops off noticeably for lower output levels.