So far, our solar power system has provided a little over 65% of our electrical needs. I’ve been keeping a spreadsheet of the daily electric meter readings (delivered, which is what we got from the electric company; received, which is what we shoved back to the electric company; and net, the difference, which what we’re paying for). Add on the power produced by the solar panels, and I can calculate what our consumption was and how much of that was covered by the sun.
We had a string of cooler and sunny days, and without the AC running, we were able to push that electric meter backwards a good bit. I calculate that we had about 11 days of “free” (in quotes, because the system still hasn’t paid for itself yet) electricity, with our surplus offsetting some days when we had a deficit.
As winter comes, the days will get shorter and that will eat into our production, but then again we won’t be running the AC, so we should come out ahead.