1st Annual Summary Report, Year Beginning April 2010

This summarizes our energy production and consumption over the first full year since we activated the solar electric system on April 1st 2010, through the end of March 2011.


Solar electricity produced: 6116 kW h (16.8 kW h per day)
Electricity consumed: 5475 kW h (15 kW h per day)
        Non-heating: 4100 kW h,  heating: 1085 kW h

Net electricity surplus: 641 kW h (12%)


We had hoped to end the year with a larger surplus than 12% but nevertheless we did export significantly more energy to the grid than we consumed. In addition we burned nearly a cord of firewood in the wood stoves so including the energy in the wood, our house still consumed more energy than it produced. But since the firewood was harvested on-site and is carbon-neutral except for a little gasoline to run the chainsaw, we were able to keep our home's carbon footprint close to zero. About 20% of our electric consumption was used for the back-up electric heat that we used during the colder winter months, and we hope to reduce that next winter. Here's a graph showing our cumulative production and consumption over the course of the year:

If we consider only the electricity that we consumed and not what we produced, our electric bill would have been about $600 for the entire year for all electricity including space heating and hot water. To buy the firewood we burned would have added another $100 or so.

Here's a graph showing the inside (blue) and outside (red) temperatures that we recorded throughout the year. Not surprisingly, the cold temperatures correlate with the sharp increase in the slope of the blue curve above because we used a significant amount of electricity for back-up heating during those periods.

On the whole we're happy with our home's performance in its first year, but of course we hope to do even better in the coming year.

This page was updated on Wednesday January 11, 2017