SAMPLE ELECTRIC BILL
Here is an actual electric bill from June 2009. See the red circled amounts below to figure energy use and associated cost. In this example energy costs was $125.84. The kWh useage was 1392kWh. Therefor:
$125.84 / 1392kWh = $0.09/kWh
Nine cents per killowatt hour is the actual cost of the electricity that is being bought.
The Bar Graph on the bottom left shows the monthly kWh use for the past year. The maximum use in August was about 2100kWh while the minimum use in March was about 700kWh. Based on this graph, an estimated average monthly use is approximately 1100kWh. So, a system that is designed to produce 1100kWh/month (about a 9kW system) would supply 100% of the yearly electric need. A larger system would be overkill. Any system smaller than that will decrease the electric bill proportionately.