I live in sunny Tucson, Arizona.
A solar power paradise, payback very fast I should imagine...
Yeah, but you use a lot of that power just running the air cons.
Like I said, we were running the swamp cooler through May. (OK, I realize that the whole concept of an evaporative cooler makes no sense in the UK.) We turned it on in late May because, well, why not, it was hot.
We were sending back to the grid between 400 and 500 kWh for the months up to May. For the May bill we sent back 216 kWh. The bill ending June 25 we used 422 kWh in excess of what we generated; that is, that month was the first month since the panels were installed (started up beginning of last September) that our use exceeded our generation. We used about the same amount of power this June as last June, about 1600 kWh, which cost almost $250 last year.
Even though May and June are hotter than July (June has many days over 110 degrees F), July is typically the month with the most energy usage here. That's because the humidity becomes unbearably high, as our monsoon season starts. We don't get monsoons in the tropical sense; the native word for the storms is "chubasca," but basically every day starts out hot and dry and as the day progresses, moisture in the air builds up and in the late afternoon we get thunderstorms and a lot of rain, and an hour later both the temperature and the humidity drop significantly. But during the day, before the storms, it's hot and sticky so we run the A/C, and that's our energy use.
Monsoon "season" lasts from July to the middle of September, and its start is defined as when the dew point exceeds 54 degrees F for three consecutive days.
Of course, today it was rainy and the temperature never got above 80 degrees and we opened the windows.
ANYWAY, we have nearly 1300 kWh in credit (what we've generated in excess of what we've used) and my guess is that even with another month of high-ish humidity and temperature, we will end up not paying anything to the utility for our electricity usage.
I really think that in the desert southwest, not having solar panel installations for both residences and businesses is a mistake. The problem is that the incumbent utilities are wholly against residential solar power and probably don't want businesses to have solar power, either. But rather than invest in solar farms and even installing the panels for customers, they'd rather continue to push the natural-gas-fired turbines as the only source for electricity.