Solar Energy is electromagnetic radiation (including infrared, visible and ultraviolet light) released by thermonuclear reactions in the core of the sun. With a few exceptions (eg, nuclear energy; geothermal energy), solar energy is the source of all energy used by mankind. Indirect forms include hydroelectricity, ocean thermal energy, tidal energy and wind energy; the sun also powers the process of photosynthesis that is the original source of the energy contained in biomass, peat, coal and petroleum. Usually, however, the term solar energy refers to the portion of the sun's radiant energy harnessed for a specific purpose by man-made devices.

A further distinction is often made between "active" and "passive" solar systems: active systems capture energy by mechanical means (eg, rooftop collectors, focusing mirrors); passive systems incorporate solar principles (eg, into the design of buildings through south-facing windows), without special mechanical systems. Most energy statistics refer only to active solar-energy systems, thus vastly understating the importance of solar energy. Active solar energy accounts for only a tiny fraction of Canada's energy use, but some studies have indicated that it could meet as much as 5% of the country's energy needs by the year 2025.

Low intensity and high variability have limited the use of active solar energy in Canada. Most purposes demand that the energy be concentrated into useful quantities and require either a storage system or a supplemental energy source for nighttime and cloudy days. Technologies have been developed for these purposes, but until recently most of them have been too expensive and too untried for widespread use. The main applications of solar-energy technology in Canada have been for space heating, domestic hot water, and for drying crops and lumber.

Photovoltaic cells are used in some remote areas of Canada to power radio transmitters and navigational aids but have been too expensive for widespread use. Photovoltaic cells are used in many consumer electronic products, such as calculators and watches. Other countries have developed solar systems that produce steam to run conventional electrical generators, but this work has not been pursued in Canada. At northern latitudes, the solar resource is too seasonally variable for exploitation of many energy applications developed elsewhere. North of the Arctic Circle, there are periods during the winter when the sun remains below the horizon.

The Future

The sun delivers solar energy to all parts of Canada. Direct use of this ambient energy minimizes the need for expensive and inefficient transmission and delivery systems. The remote expanses of Canada, where costs of conventional nonrenewable energy are high, offer opportunities for developing and using many cost-effective solar technologies. Although the continuing supply of solar energy is free, the capital cost of capture hardware can be expensive, but if compared to marginal cost of conventional sources it can be cost competitive. However, simple passive-heating systems may only increase the cost of buildings by 1-5%.

Active systems usually require several years of operation to recover the initial cost of operation in fuel savings. Until economic support structures match those for conventional energy sources, solar energy will have difficulty competing in all but remote or small applications. However, once the system is in place, delivery energy costs are stable and immune to market fluctuations that affect conventional nonrenewable energy resources. The Solar Energy Soc of Canada is the national technical organization that promotes education and the dissemination of information on all aspects of solar-energy use. It is affiliated with the International Solar Energy Soc. The Canadian Solar Industries Assn is a manufacturers' organization promoting industrial development.