- Save money every month by reducing your electricity bills.
- Participate in net metering. Generate credit from the electric utility for the energy you produce.
- Save money on the initial investment with utility rebates and federal tax credits.
- Hedge against future electric rate increases.
- Take advantage of the reliable, mature technology with PV modules typically backed by a 20- to 25-year power output guarantee and 15-year warranty on inverters.
- Protect the environment by reducing pollution and greenhouse gas emissions, thus lowering your carbon footprint, and advancing local and national energy independence and security.
- Enjoy the self-reliance that comes with producing your own power.
- Increase the value of your home when purchasing a solar system.
About Solar Electricity
The knowledge of photovoltaics was set in motion in 1838 with two French scientists experimenting with the generation of electricity through chemical reactions. They noted that exposing an experimental apparatus to sunlight increased the output of electricity. In 1954, Bell Laboratories announced progress that finally allowed photovoltaics to leave the lab and move into practical application-first in space then on Earth.
Today, solar electric systems are in use worldwide and in space. They are a reliable, mature technology. PV systems provide power to homes, businesses, and industry. They are a source of generating capacity for some electric utilities. Solar electric can be found in cities, towns, rural areas, and areas that do not have access to utility grid power.
How Grid-Tied Solar Electric Systems Work
Solar PV modules collect the sun’s energy and convert it into direct current (DC) electricity. The amount of electricity produced is proportional to the amount and intensity of sunlight.
The number of panels is determined by the home or business’s power needs. Typically 2,000 to 4,000 watts (2-4 kilowatts, kW). A DC to AC grid-tied inverter converts the electricity from DC to alternating current (AC) for use in a home or business. A rule of thumb is 100 square feet of PV module area per kilowatt (kW) of electricity produced by PV. A typical solar electric system for a home will require approximately 200-500 square feet.
A bi-directional (spins both ways) electric meter records and displays “net” power usage. Net power is the difference between what the solar electric system generates and what the electric utility provides to meet a home or business’s total energy requirements. When more electricity is generated than is used, the meter spins backward, lowering the electric bill. When less electricity is generated, the meter spins forward, although at a slower rate than it would without the PV system. The overall result tracks the net difference as electricity is generated and sent off to the grid and as electricity is consumed. This, then, becomes the basis for payments (credits) to your electric bill. This all happens seamlessly and automatically. No user intervention is required.
Energy storage (batteries) in a grid-tied system is rarely needed or justified. The electric grid acts as “storage,” accepting excess power that is produced and allowing it to be used by others. When the PV system does not produce power (nighttime) or produces less power (cloudy weather), the electric grid becomes the source, seamlessly switching over. While there are energy storage solutions, the cost–combined with a short lifespan and maintenance requirements–makes them less of a solution. Unless you’re off the grid, storage rarely makes sense. Finally, not having batteries in a system reduces the overall cost and virtually eliminates maintenance of any kind.
How Off-Grid Solar Electric Systems Work
In an off-grid solar electric system batteries are required. They store energy and allow the system to provide power during cloudy weather and at night. Many aspects of an off-grid system are similar to on-grid. The notable exceptions being the methodology used for sizing the system (an off-grid system typically supplies all the power requirements of the home, sometimes supplemented by a gasoline or propane generator), the inclusion batteries (for energy storage), and the addition of charge control equipment necessary for managing the charge and discharge cycles of the batteries. The inverters are also different in that they usually incorporate battery charging capabilities.