Types of Solar Electric Systems for the Home

Solar power is a form of energy derived from sunlight and falls under the category of a renewable energy source, meaning the energy may be captured and collected without depleting the supply or harming the source. A solar electric system is necessary for capturing and converting the sun's energy into usable power.

How Sunlight is Converted to Electricity
Sunlight is available to any given location on the Earth for a certain amount of hours out of each 24 hour cycle. The daylight hours provide a sufficient amount of time for devices known as solar panels to collect sunlight via photovoltaic cells. These cells are made up of a semi-conducting material, usually silicon that converts the sunlight into electricity. When the cells within the panels are no longer exposed to sunlight, that is, the energy source is no longer available, the cells cease to produce energy. The electricity produced during exposure, however, may be stored.

Types of Solar Electric Systems
Solar panels are one component of a solar electric collection system. The three types of systems commonly used are grid-intertied, grid-intertied with battery back-up and a stand-alone system also known as off-grid. The grid referred to is the infrastructure already in place for delivering electricity to any given region.

Grid-intertied Solar Electric System
Homeowners with installed solar systems may use a grid-intertied system in which converted energy (the electricity produced when the sun hits the solar cells) is diverted to the existing infrastructure -the grid- and subsequently to the local power company that supplies electricity. The homeowner is credited with the electrical input from his system, subsequently lowering his electric bill.

Grid-intertied System with Battery Back-up
In this type of system, converted energy is stored in an array of batteries. Much like car batteries, solar storage batteries are designed to deliver electricity when accessed. In a battery back-up system, the stored electricity is used when electricity from the grid isn't available, such as during a black out.

Off Grid System
An off-grid system delivers the converted energy to the bank of storage batteries, which in turn feeds directly back into the internal housing system. All power generated from the solar panels is stored and directed back into the home or building without any connection to the existing grid tied to the power company.

The Cost of Solar Energy as a Power Source
The three systems used to collect, store and distribute solar power ultimately result in free electricity. The disadvantage to obtaining free electricity is the cost of the equipment to do so. Solar electric systems are expensive, requiring several thousand dollars in upfront costs. It may take several years before the system pays for itself in the form of free electricity to the homeowner. This low return on investment may be offset by tax incentives and rebates at both the federal and state level.

References:

Homepower Magazine: Solar Electricity Basics
Union of Concerned Scientists: How Solar Energy Works

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