What is Solar Water Heating?

Solar Water Heating Overview

This information will help you understand how solar thermal collectors take the sun's rays and convert them into heat for warming of water.

Solar energy can heat water for at least four different applications:

  • potable (drinking) and service use (washing) use in homes
  • potable and service use in commercial, and institutional and industrial facilities
  • radiant floor heating
  • swimming pools (indoor or outdoor).

Almost all applications use collectors, which are aimed at the sun to collect as much radiation heat as possible. There are three basic types of collectors:

  • seasonal collectors (these units are simple design and often circulate water through plastic pipes, they offer little protection from freezing)
  • flat plate collectors (these units may circulate an anti-freeze fluid through insulated pipes, and release the
  • collected heat through the use of a heat exchanger)
  • evacuated tube collectors (these are highly insulated glass cylinders which maximize the absorption of heat and minimize the loss of heat from the system).

Generally speaking, the three types above offer increasing collection efficiency and increasing cost of installation.

The number of collectors required for a site depends on a number of factors, such as the size of your load (ie: how much water do you need to heat), the efficiency of the unit, the amount of solar radiation at the site, the amount of storage available, etc.

Collectors should be aimed as south as possible, and installations require unobstructed access to the sun's path in all four seasons. Systems can be designed to provide 100 percent of your water heating or to use the solar energy as a supplement to a conventional heating facility.

For an accurate assessment of your needs and a site assessment, a qualified system designer can provide guidance. We recommend that you rely on a CanSIA member, who has agreed to comply with a Code of Ethics to ensure satisfaction for your specific installation.

Natural Resources Canada has developed a free software program, called RETScreen, that can assess the feasibility of a solar water heating installation in any region of Canada. It runs on Microsoft ExcelTM, and is available free of charge by downloading it off the internet from RETScreen.

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