Solar Energy

 

The solar energy reaching the earths land surface is estimated to be over 1,000 times greater than the world's total energy demand. In the UK, 1,000 KWatt Hours of energy falls on each square meter of ground every year, that's 2.7 KWatt Hours per square meter per day or an average power of 114 Watts.

 

Solar panels capture the suns energy directly. Photovoltaic (PV) panels generate electricity, other solar panels can be used to heat water. Up to 2/3 of the hot water used by the average household in Britain can be heated using solar energy.

 

Solar Water Heating Panels

 

The sun's energy may be used to heat water in solar water heating panels. These come in two basic types;

 

  • Flat Panel Collectors; A flat metal panel containing water channels is enclosed in an insulated box with a clear lid. The panel is usually painted black to improve efficiency and the box acts as miniature greenhouse. Water circulating through the panel is heated by the sun's energy.
  • Evacuated Tube Collectors; A single tube containing a heat transfer fluid is contained within an evacuated gas tube. Water is passed through a manifold at the upper end of the tube to be heated. These collectors are more efficient (and expensive) than flat plate collectors but require a smaller area to heat a given amount of water.

 

Solar water heating systems will typically supply 40 to 66% of a household's annual hot water requirement depending on the pattern of hot water use and type of system installed.

 

Photovoltaic Panels

 

Photovoltaic solar panels are used to generate electricity. Again they come in two types; amorphous silicon and crystalline silicon:

 

  • Crystalline silicon panels are made from individual cells of silicon crystals. They have a blue appearance and the individual cells from which they are made can be seen.
  • Amorphous silicon panels have a brown appearance, they are cheaper than crystalline silicon panels, but less efficient and therefore require a larger panel area for the same electrical output. The cost of mounting these larger panels often outweighs the cost advantage of the panels, although are often used in small appliances such as calculators.

 

In Britain the typical power output of a photovoltaic solar panel is about 2 KWatt Hours / Day for every 1 KWatt of rated peak power capacity, thus a 70 Watt panel will give about 140 Watt Hours / Day on average. However much of this energy will be produced in the summer: the average power generated by a 1 KWatt solar array in the summer will be about 30 KWatt Hours / Day, but this will drop to about 8 Watt Hours / Day in the winter.

 

Sage Green Technology has the solutions and experience to help you live in harmony with your natural surroundings.