A photovoltaic (PV) power system:
The system shown above is isolated from any sources of outside electricity. For this reason, it is known as an "off-grid" system. This is the type of system in Maryland LEAFHouse. However, a home does not need to be powered exclusively by solar energy to take advantage of its benefits.
Two options are available to homeowners who live in an area where utility grid electricity is available. These systems are known as "grid-tied" or "utility-interactive."
The grid-tied option is less expensive and has no battery bank; electricity from the PV panels goes directly to the inverter. When the PV panels generate more electricity than is needed by the home, the excess electricity is fed into the utility grid. The house electric meter runs backward, and the local power company effectively buys the surplus energy from the homeowner. At night and other times when the home needs more electricity than the PV panels can provide, normal grid electricity is used. The inverter controls the use of PV and grid electricity seamlessly.
The utility-interactive option has a PV system with batteries and a charge controller, essentially an off-grid system, but provide a connection to the utility grid as well. If the PV panels and batteries cannot generate and store enough electricity for the home, grid electricity is used.
The advantage to grid-tied systems is that homeowners can take advantage of solar energy, without having to worry about long periods without sufficient sunlight, and without having to buy a large bank of batteries.
Federal, state and local government programs currently provide monetary incentives to homeowners who wish to install PV systems. These programs offer grants and tax-credits that pay a significant portion of the up-front system cost. A comprehensive list of state incentives can be found on the Database of State Incentives for Renewable Energy (DSIRE).
Please read ahead for descriptions of the components that make up a PV system, from the sun to the electrical outlet!
The photovoltaic (PV) power system harnesses energy from the sun to generate electricity.