Photovoltaic and Thermal Solar Renewable Energy Sources

Solar Solar energy is the heat and light radiated from the Sun that powers Earth's climate and supports life. Solar technologies allow controlled use of this energy resource. Solar power is a synonym of solar energy and refers specifically to the conversion of sunlight into electricity by photovoltaics or conversion in to thermal energy. EnergyXchange uses solar energy for both electricity and thermal heat.

Photovoltaic systems convert sunlight directly into electricity through the movement of positively and negatively charged particles. Currently the EnergyXchange campus has over eight kilowatts (kW) of photovoltaic generating capacity. The three arrangements of modules or arrays, follow the sun with a non-motorized tracking device. The tracker uses only the sun’s heating of Freon inside the device, converting it from a liquid to gas to liquid it as moves and settles as a counter weight. This increases the systems’ electrical generation by 20-30% and negates electrical losses that occur during the conversion and transmission processes.

EnergyXchange has contracted with the power company and NC Greenpower to "net meter," whereby the electricity produced is used by the facility without the need for storing it. Excess electricity is exported to the electrical grid and sold to our neighbors by the utility. This produces a credit or virtual "battery" that we draw upon on cloudy days. EnergyXchange only draws electricity from the grid when more is needed then is being produced at that particular time. We also demonstrate a "sell all" meter where solar electricity is exported for sale to the utility at a premium rate and purchased back by EnergyXchange at lower cost. This type of metering provides for utilization of the solar energy at the site and a net profit as incentive for producing green power. For particular information on these agreements contact your local power company and visit www.ncgreenpower.org for information regarding tax credits.

In addition, EnergyXchange has ten solar thermal panels that provide heat for the aquaponics fish tank. Heated water and glycol are circulated from the thermal panels through coils in the fish tank and back to the thermal panels. In this manner, the water in the fish tanks is maintained above 60 degrees even in the winter.

Photovoltaic (PV) Systems

Photovoltaic systems convert sunlight directly into electricity. Commonly known as "solar cells," these systems already power more than one billion handheld calculators, as well as millions of watches, portable lights and battery chargers. Larger, more complex systems provide electricity to pump water, power communications equipment, light homes and operate appliances.

The heart of a PV system is a solid-state cell made of semiconductor material like that used in microelectronics. It's usually silicon, the basic ingredient in common beach sand.  The cell's semiconductor "wafer" is specially treated to form a positive electric field on one side and a negative field on the other, and electrical conductors are attached to both sides.  When sunlight strikes the cell, it knocks loose electrons, which are captured in the form of electric current.

Thermal Systems

Thermal systems convert sunlight into thermal energy, most often providing heated water.  The overall process involves the use of solar collectors filled with water, or some other fluid, being place in a location with good access to direct sunlight.  The heated water is then piped to a location where the captured heat can be used to provide hot water for personal use or comfort heat.

For more information on solar energy, check out these links:
www.gosolarnc.org
http://www.ncsc.ncsu.edu/
http://www.ases.org/

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