Buildings consume vast amounts of energy. More than two-thirds of the energy used in the United States goes to heating, cooling and lighting buildings. PV systems can be integrated into every building, new or old, to harness the sun’s energy to generate electricity. Grid-tied PV systems are wired into buildings that are connected to the utility grid; hence the term "grid-tied." Energy produced by a PV system can be used directly in a home or business and, if there is an excess, flow out through the electric meter, providing power to others.

Recent laws in more than a dozen states mandate that PV system owners get credit for this excess power. In California, state electric utilities will "bank" any unused solar-generated electricity, essentially allowing the electric meter to run backwards when PV output is greater than the electricity being consumed on-site at the moment. At night or on cloudy days, PV system owners can then draw upon this stored credit from the utility grid. Other states credit the customer’s utility bill directly at a legally pre-determined rate. This arrangement is called "net metering" and helps to improve the economics of a grid-tied PV system.

Net metering is especially compatible with solar power when time-of-use rate schedules are employed. Most electric usage tends to concentrate in the low-rate periods in order to save money. PV systems, on the other hand, are generating the most power when the sun is brightest in the middle of the day – generally when the rate is at its peak. Seasonal rate changes also favor the summer-intensive output of a PV system. This arrangement means that a solar power system can earn energy credits by as much as four times the rate that they are consumed. The result is a smaller, more affordable system to offset the required electric demand.