As a general rule, on a clear day, the solar insulation striking the earth when the sun is directly overhead is approximately 1,000 Watts per square meter. While the usable energy extracted from that will depend on the efficiency of the photovoltaic cells and the other electronics in the energy pathway, a reasonably efficient and sized array can produce significant power almost anywhere in the United States.

For residential customers, this means that even a moderately sized array can produce enough energy to either significantly reduce or even offset your electrical bill. Using a system that is tied in with the utility grid, a method generally available throughout the U.S., allows you to sell or transfer excess power back to the grid during the brightest parts of the day, drawing power back from the grid during the evening or on cloudy days. Customers seeking full independence from their utility company will want to add a battery storage component to store energy for nights and overcast periods.