Technology
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Solar Hot Water systems (SHW) are a mature technology that was first used for industrial and commercial applications in the late 1800s, about the same time it was applied to domestic purposes. While certainly the sun has been used to heat water for much longer, the technology, while advanced and matured, is quite similar to that which came on the market over a hundred years ago. Over the years, significant research, development and experimentation has lead to a highly developed and market ready technology. Solar hot water systems for industrial and commercial applications are basically the same technology that is used for domestic solar hot water systems except on a larger scale (see SDHW - link).
An estimated 606 000 m2 of solar thermal collectors are currently in use in Canada, a fraction of which are used in commercial solar water heating systems. Following the collapse of oil and gas prices in the mid-1980s and the termination of off-oil government programs, sales of new systems slowed down considerably. As a result of strong public interest, improved economics and government incentives, active solar deployment in Canada should accelerate. Presently, a few hundred new systems are installed annually, representing sales of $2-3 million. http://www2.nrcan.gc.ca/ES/OERD/english/view.asp?x=1571&mid=540
Solar hot water systems use the sun's energy to heat water for a variety of industrial and business uses. Any company that uses large amounts of hot water can benefit from a solar hot water system. The system is particularly useful for agricultural applications such as heating water for fish hatcheries, cleaning and sterilization of equipment, for businesses like restaurants, nursing homes, car washes and laundry facilities and for any industries that require large volumes of hot water. For example, a co-op bakery in Minnesota uses seven 4' by 8' hot water panels to reduce their use of gas for heating water by one third (www.wedge.coop).
Fish hatcheries heat large volumes of low-temperature fresh water to enhance fish growth. Some hatcheries use unglazed solar collectors to provide 25 percent of their annual heating needs. In some cases, they have reduced conventional fuel costs by tens of thousands of dollars.
http://www.canren.gc.ca/prod_serv/index.asp?CaId=157&PgId=806
Solar hot water technology works in both hot and cold climates, and works well throughout Canada. Solar Hot Water collectors can be mounted on roofs, walls or the ground. The collectors absorb heat energy from the sun and transfer that heat to a storage tank, usually with a heat exchanger. Two Solar hot water systems appropriate for climates that experience freezing are Closed Loop Drain Back systems or Closed Loop Anti-Freeze liquid (usually propylene glycol) systems with heat exchanger systems. Collectors can be unglazed (low temperature needs, such as swimming pools), glazed flat plate collectors (usually for temperatures up to 60 degrees Celsius) or vacuum tube collectors (able to heat water to temperatures above 80 degrees Celsius). The collectors have different characteristics and the choice of collector will depend on temperature, seasonal hot water needs and other design requirements. Appropriate sites for solar hot water systems have a clear southern exposure close to the hot water load free from shading from about 10 AM to 3 PM or longer. Size of the collectors and storage tank will depend on factors such as the climate, solar exposure and amount of hot water required.
Components of a Solar hot water system, in addition to solar collectors, heat exchanger and storage tank(s), can include tank and pipe insulation, a circulation pump (AC or DC), PV panel (to run DC circulation pump), water reservoir (for drain back systems), thermostatic controls, timers, connecting pipes, collector mounting structure, filters, heat and flow meters, pressure gauges.
Modified: 02-13-2008
