Solar power

Solar energy can be extracted and used in two days, for heating (solar thermal) and for generating electricity (solar photovoltaic)

Solar thermal energy is energy harnessed from the sun’s rays though solar thermal collectors. While only 600 megawatts of solar thermal power is up and running worldwide in October 2009 according to Dr David Mills of Ausra, another 400 megawatts is under construction and there are 14,000 megawatts of the more serious concentrating solar thermal (CST) projects being developed.

There are 3 types of solar thermal collectors:

Low-temperature – Unglazed plastic or metal flat plate collectors are used for swimming pool heating and glazed perforated solar air collectors are used for commercial building air heating.

Medium-temperature – Glazed flat plate and vacuum tube collectors are used for mid-range temperature applications such as domestic hot water and space heating and cooling applications. In locations with average available solar energy, flat plate collectors are sized at approximately 0.5 to 1 square foot per gallon of daily hot water use. Evacuated tube collectors have absorber plates that are metal strips running down the center of each tube.

High-temperature – Concentrating collectors that focus the sunlight onto a much smaller area are used for higher temperature applications such as industrial process heat, absorption cooling, and large-scale solar thermal power applications to generate steam for electricity generation

Advantages of solar thermal collectors:

-      Emission Free

-      Cost effective in facilities where traditional heating methods are expensive

-      Service Off-grid locations where grid electricity is not available or unreliable

-      Low operating cost. No fuel required

Disadvantages of solar thermal collectors:

-      Subject to location, seasonal and weather factors. Thermal collectors subject to availability and intensity of sunlight

-      Environmental implications associated with large surface area needed for sunlight collection

-      High capital cost

-      energy conversion rates or efficiencies are low compared to other energy sources