Energy from the sun travels to the earth in the form of electromagnetic radiation similar to radio waves, but in a different frequency range.  Available solar energy is often expressed in units of energy per time per unit area, such as watts per square metre  (W/m²).  The amount of energy available from the sun outside the Earth’s atmosphere is approximately 1367 W/m²; that’s nearly the same as a high power hair drier for every square meter of sunlight!  Some of the solar energy is absorbed as it passes through the Earth’s atmosphere.  As a result, on a clear day the amount of solar energy available at the Earth’s surface in the direction of the sun is typically 1000 W/m².  At any particular time, the available solar energy is primarily dependent upon how high the sun is in the sky and current cloud conditions.  On a monthly or annual basis, the amount of solar energy available also depends upon the location.  Furthermore, useable solar energy is depends upon available solar energy, other weather conditions, the technology used, and the application.

There are many ways that solar energy can be used effectively.  Applications of solar energy use can be grouped into there are three primary categories: heating/cooling, electricity production, and chemical processes.  The most widely used applications are for water and space heating.  Ventilation solar air heating is also growing in popularity.  Uptake of electricity producing solar technologies is increasing for the applications photovoltaics (primarily) and concentrating solar thermal-electric technologies.  Due to recent advances in solar detoxification technologies for cleaning water and air, these applications hold promise to be competitive with conventional technologies.

The advantages of solar energy

Solar energy has the following advantages over conventional energy:

• The energy from the sun is virtually free after the initial cost has been recovered.         
• Depending on the utilization of energy, paybacks can be very short when compared to the cost of common energy sources used.         
• Solar and other renewable energy systems can be stand-alone; thereby not requiring connection to a power or natural gas grid.         
• The sun provides a virtually unlimited supply of solar energy.         
• The use of solar energy displaces conventional energy; which usually results in a proportional decrease in green house gas emissions.
• The use of solar energy is an untapped market.

Applications of solar energy

The following table shows some applications of solar energy, who uses it and how the energy is obtained.  Not all applications listed exist in Canada and this is not a complete list of all solar energy applications in use around the world.