Green Power - A Consumer Guide to Green Power in Canada

WHAT TO KNOW

What are Green Power Technologies?

SOLAR

Considered by some people to be the most versatile of the Green Power sources, solar energy is clean and inexhaustible and can be harnessed using three different technologies. Only one actually generates electricity – solar photovoltaic. The other two perform functions that can significantly reduce power consumption, where electricity is being used for such services as water and space heating.

Photovoltaic

Photovoltaic (PV) cells convert sunlight into direct current electricity. These systems are mainly used in remote areas where they provide electricity to power lights, water pumps, satellite receivers, computers, refrigerators and other household appliances. Building-integrated photovoltaics is a rapidly growing technology in Canada. Houses and office buildings are being constructed with PV arrays built into the walls, roofs and windows. These systems provide power to the buildings. They can also provide excess power to the grid, with some buildings having a net reduction in electricity demand.

Passive

Passive solar air pre-heater ventilation systems can be mounted on the outside walls of buildings or incorporated into the building structure to pre-heat outside air before it enters the building's ventilation system. This can reduce the need for other heating sources, such as electricity or fossil fuels. Passive solar design uses a building's roof, walls and windows to control the amount of the sun's energy that is absorbed or lost. In the Canadian winter, a south or southwest facing window efficiently captures the sun's energy, and insulated windowpanes keep it inside in the form of heat. This principle also works in reverse to keep a building cool in summer. Painting a building a light colour reflects sunlight. Awnings and shutters on windows and long overhangs on roofs help to block the sun. Leafy trees and shrubs also perform this function.

Active

Active solar technology uses collectors to heat air and water in houses, offices, factories and other buildings. Glazed and insulated collector panels are used to heat water when its temperature must be in the 30 to 70 °C range — household hot water, for example. Unglazed collectors are not insulated and are used to heat swimming pools. Glazed collectors can also heat the liquid to run radiant floor or baseboard heating systems. Typically, homeowners use solar water and space heaters in conjunction with a backup electric or gas heating system. Research is under way on systems that concentrate the sun's power on one spot, producing steam to drive a turbine and generate electricity.