PV systems can be designed to generate the majority of the electricity used in your home, or just a portion of it. In general, your solar system will not be designed to offset 100% of your electricity needs. This is because it makes more financial sense to get some of your electricity from solar energy and the rest from your utility company (i.e. in the daytime, solar electricity is bountiful but utility electric rates may be at their peak; at night, your system won’t produce any solar energy, but you can use cheaper, off-peak electricity from the utility company).
For a Midwest example, the average residential home uses approximately 720 kWh of electricity per month. A 3.5 KW PV system would offset more than half of the average household’s electricity consumption. This size solar system would require about eighteen 200-Watt PV panels.
The size of your solar system depends on a number of factors:
- How much electricity your home uses
- Angle, pitch, and direction of your roof
- Unobstructed roof space that is available