Since we purchased the Chevy Volt, I have installed five more solar panels on my workshop building to achieve a total array specification of around 5.8 kW peak capacity. On a good sunny day our solar array can generate over 30 kWh, while the Volt requires a little over 13 kWh for a full charge. In theory that should leave us with a significant surplus in the summer and allow us to drive the Volt for free on those days. In reality we have yet to see a zero or negative monthly electric bill, partly because it has been an unusually overcast year to date (climate change?).
I had hoped that the additional panels would help to offset the charging power that the Volt uses via the 240 V charging station that draws 3700 Watts for 3.5 hours to fully charge the vehicle. So recently I decided to go through all of my solar power data and the records I keep of weekly charging power for the Volt and calculate what our electric bill would be if we did not have an electric vehicle. Here is a chart that I created showing our calculated monthly energy bills:
The calculated average monthly bill would be $10.57. This was my original goal for the solar power system - to provide almost all of the power for our home. So essentially I have accomplished that, now I have to think about where to put additional panels to offset the power needed to charge the Volt! I have been eyeing the east facing roof of the house, but my concern is that it is so high that I would be uncomfortable doing the installation with the help of neighbors and friends. I really dislike paying other people to do things I should be able to do myself. So for now this is a stalemate.