Photovoltaic Power System
The photovoltaic (PV) power system harnesses energy from the sun to generate electricity. This system . . .
- Generates electricity through the use of PV panels (also known as solar panels).
- Charges batteries that store the electricity
- Converts electricity to standard, household alternating current (AC).
Here is a typical 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 the 2005 Maryland home. 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-tie" or "utility-interactive."
The first, lower-cost option forgoes the use of batteries completely and feeds electricty from the PV panels to the inverter, eliminating the need for a charge controller. When the PV panels generate more electricity than is needed by the home, the excess electricity is fed back into the utility grid. This surplus power is bought back by the local power company, and is usually credited on the homeowner's electric bill. At night, or 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 second option is to have 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-tie systems is that homeowners can take advantage of the use of solar energy, lower their electric bills, and still have reliable grid electricity - all simultaneously.
Many localities provide monetary incentives to homeowners who wish to install PV systems. Often, the local or state government will pay for a significant portion of the up-front system cost and provide tax credits for the use of PV systems. A comprehensive list of state incentives can be found on the Database of State Incentives for Renewable Energy (DSIRE). In addition, BP Solar has a Solar Savings Estimator that will calculate the cost of a typical installed system, taking into account some incentives available in your area.
Please read ahead for descriptions of the components that make up a PV system, from the sun to the electrical outlet!
Department of Energy Solar Decathlon Website