We don’t typically think of our home polluting or having impact on the environment. Buildings (homes and businesses) consume two-third of of total U.S. electric demand. New structures may be more energy efficient due to newer heating and cooling systems, energy-star™ appliances, better insulation, windows and doors.
The U.S. Green Building Council’s Leadership in Energy and Environmental Design (LEED) has set guidelines for “green” buildings that many customers and builders are embracing. In general, any improvement to the efficiency of your home (reducing your total energy consumption) helps to reduce the size of the solar installation needed or it allows the solar to satisfy a higher portion of your energy requirements. In short, energy efficiency and energy conservation amplify and complement the values and benefits to having a residential solar energy system. This section will help consumers understand the different types of solar energy systems used in residential
Photovoltaic Solar Panels -
Unlike a solar hot water system, which is essentially a plumbing device, PV uses semi-conductors and sunlight to make electricity. The more solar modules a PV system or array has, the more electricity will be generated. DC electricity can be “inverted” into alternating current (AC), so it can be useable power for any home or business.
PV systems to power buildings fall into four general categories:
- Grid-Interconnected or “Grid-Tied” PV systems are the most popular and use special inverters to allow electricity to flow safely back into the electric grid. When solar power is generated, this power is typically first used by the building, and then surplus electricity can actually flow back into the grid, giving full retail credit per kilowatt-hour from your utility provider. Since there are no batteries, these systems cannot stored energy and are designed to shut down if the grid is down for safety reasons (mainly to protect utility line workers).
- Grid-Interconnected with Battery Back-up systems offer customers continued power when the grid goes down, while still being connected to the grid for seamless power. Newer systems also accept other power sources, in addition to PV, such as wind or even traditional gas-powered generators to provide power and/or charge the battery at night and/or if the grid is not available.
- “Off-Grid” PV systems are used when a completely independent or “stand alone” system is needed. Since no grid power is used, the system must be carefully designed based on power usage, peak demand and seasonal solar variations. Batteries are typically used to provide power at night, in low sun or high electric demand conditions. These systems are ideal for remote locations where no utilities exist.