- 6655 kWh were purchased from Puget Sound Energy
- 3512 kWh were produced by the PV array
- 2322 kWh were put back into the grid
- 1190 kWh produced by the PV array were used on site
- ~1000 kWh were used by the propane range
How does the house compare with other houses in the US? The average US house of similar size used 29,893 kWh annually. The corresponding numbers for the western US and for Washington state are 22,683 and 24,360 kWh. Not taking the PV array into account, the house used 29% of the energy of the average US house. If we include the electricity produced by the PV array as an "internal" source of energy, the house used 18% of the energy of the average US house.
The graphs below, which are a great feature of the PSE website, show electricity usage on a daily basis for a summer month, August 2011, and for a winter month, January 2012.
The summer data is representative of all usage except heating, and averages about 7 kWh per day. The winter usage is significantly higher because of the space heating load. Because the days are shorter, the lighting is in more use in the winter than in the summer. Note how the energy used peaks around January 18, when the low temperature was about 22 F. The third figure shows the total electricity usage for June 2012 relative to other users in the area. I'm a bit puzzled by the big difference and assume that most homeowners had to heat their house even in June.