The sun is an enormous producer of clean, renewable energy. Harnessing this energy and converting it into a solar electricity system is now possible even for the average homeowner. Here is information on how a small solar electricity system works and how it can provide power to your home or business.
Solar electric systems convert solar energy into a usable electricity stream through the use of photovoltaic cells. When sunlight is absorbed by the cells, the solar energy knocks electrons loose from the component atoms in the material the cell is made of and energy is created. This energy then travels into a circuit built into the cell where an electrical current is formed. Currently, a single solar cell can produce only a small amount of usable electricity on a day when there is clear sunlight. To produce the large amounts of electricity a home or business normally uses, many small cells are wired together into panels that are also wired together to form what is called an array of panels. These panel arrays can be mounted in a fixed position facing south and angled up towards the sun, or mounted on a tracking devise that allows the panels to move and follow the sun’s path across the sky to capture the most sunlight possible. In the United States alone, there are now tens of thousands of homes and businesses powered fully or in part by photovoltaic cells.
There are three different types of solar electricity systems: The grid-connected, grid-connected with battery backup and off-grid (stand alone). Each type has distinct applications and component needs.
A grid-connected system connects the electricity generated from the solar panels with the electric utility grid already coming into a home or business. Living with a grid-connected system is no different than living with normal utility electricity, except part of the electricity you use comes from the solar panels. This offsets the amount of electricity used from the utility grid and, in some cases, enough solar energy is produced that credits are created with the utility company. These credits can then be used to lower utility electric bills.
The electricity produced by solar panels is transferred through a direct current (DC), which must be converted into an alternating current (AC) before it can be used. This conversion is accomplished with an inverter that synchronizes the solar panel DC electricity with the grid AC electrical current. The inverter is connected to an AC breaker panel where the converted solar electricity is used directly by the home or business or, if an excess of solar electricity is produced, fed back into the electric meter to generate credits.
A grid-connected system with a battery backup requires more components between the solar panels and the inverter, but is useful when blackouts or power outages are common. The battery stores some of the electricity produced by the solar panels and can keep some or all electrical needs supplied when outages occur. Because this type of design requires more components, it is more expensive and lowers the overall efficiency of the system. But for some people, the battery backup system is worth the additional costs.
An off-grid (stand alone) system operates totally independent from a grid to supply all electricity needs. They are most commonly found in remote locations where it is cost prohibitive to bring in utility lines. A stand alone system requires the larger number of components as described above in the battery backup system to properly convert the DC solar electricity into an AC electrical flow. While a stand alone solar power system will work anywhere, they are currently limited in design for providing the total amount of electricity normally needed by typical homes and businesses. Given the current state of photovoltaic technology, people who have off-grid systems often need to make adjustments to how and when electricity is used.