Your Guide To Green

What could be more sustainable than energy from the sun?

Photovoltaic (PV) systems use solar cells to capture electrons from the sun and direct them into electrical wiring, forming a direct current (DC). This is the same kind of current that flows from a regular battery. It can be used to power a variety of devices as-is, or it can be converted to alternating current (AC) for standard household use.

Consumers can now find PV systems that are designed specifically for summer homes or for regular residences and businesses. The PV companies will help you determine the type of system you need based on the quantity of energy you'll use, the reliability you'll need and the times you'll want it available.

If you want to be "off the grid," you'll need a battery storage unit. If your building is connected to the electric utility, the battery storage is optional.

Types of PV Systems

1. Day Use System: The most simple and least expensive type of system, it wires PV modules directly to a DC appliance. There is no storage device, so power is only generated when the sun shines. High sunshine levels mean higher power output and load capacity.
2. DC Systems with Storage Batteries: Batteries store the excess solar energy, which can then be used at night or in cloudy weather, continuously or intermittently. The battery bank can also supply high-surge currents for a brief period, allowing it to start large motors or to perform other difficult tasks.
3. DC Systems Powering AC Loads: These systems include an inverter to convert DC electricity to AC electricity, making it more convenient for home use.
4. Utility Grid Interconnected Systems: PV systems that are connected to the utility grid do not need battery storage in their design, since the utility grid acts as a power reserve. Instead of storing surplus energy in batteries, the homeowner sells it to the local utility company. The meter spins in either direction, depending on whether the homeowner is adding to, or taking from, the grid.

5. Hybrid Systems: Integrates a PV system and alternative systems, such as gas or diesel powered generators, wind turbines, or hydroelectric systems.
6. Integrated Photovoltaic Battery Charging Systems: Small, all-in-one systems can be purchased to recharge batteries or to power small solar appliances, such as a solar radio, lantern or garden fountain.

Find Out More:

• American Council for an Energy-Efficient Economy: www.aceee.org
• American Solar Energy Society: www.ases.org
• Solar Rating and Certification Corporation: www.solar-rating.org