Your utility bill tracks your energy use from month to month and therefore contains useful information for analyzing your energy use. Let’s say that you compile your monthly energy use for a year and get the following:
Jan: 850 kWh
Feb: 900 kWh
Mar: 830 kWh
Apr: 780 kWh
May: 500 kWh
Jun: 700 kWh
Jul: 950 kWh
Aug: 1070 kWh
Sep: 980 kWh
Oct: 790 kWh
Nov: 840 kWh
Dec: 900 kWh
Adding these up, the total energy usage for the year is found to be 10,090 kWh.
The average use per day (divide by 365) is 27.64 kWh.
Note that 15 kWh per day is considered efficient, while 20 kWh per day is considered wasteful. The 27.64 kWh per day measured here is even worse than that! The average US household uses about 20 kWh per day. The best way to make your solar power investment pay for itself is to find ways to reduce the energy you are using to that you actually need.