The sun provides energy in two forms – light and heat. The sun can be used to heat water in our homes and businesses. It can also produce electricity. Energy produced by the sun is called solar power. Since the beginning of mankind we have used the energy of the sun to dry clothes and food, but it wasn't until 1954 that scientists in the United States worked out a way to use the sun to create electricity.
Solar energy falls into two main categories.
"Solar photovoltaic" energy
The scientists invented photovoltaic cells (or panels) to capture the sun's energy and turn it into electricity. They wanted to use this solar electricity to power satellites in space. Photovoltaic cells are made up like a sandwich - two layers of silicon containing special chemicals. Sunlight is used to charge electrons in the silicon layers. The energised electrons move through the cell and flow into a wire, creating an electric current. Solar photovoltaic power is the same technology that powers some calculators and watches. It is also used for remote telephones in some regional areas. The power of the sun is also used as a direct source in solar hot water units. Solar power is particularly useful in remote areas (and there are a lot of these in Australia) where regular electricity supply is not available. Ausgrid has a 2.75 hectare solar farm (the size of about 5 football fields) at Singleton in NSW. It is the largest of its type in the southern hemisphere and produces enough electricity (400 kW) each year to power about 100 homes. By generating electricity through the sun we prevent the release into the atmosphere of around 500 tonnes of greenhouse gases each year!
"Solar thermal" energy
Energy from the sun is absorbed and used to heat things like water. The hot water can be used directly or it can be used to create steam to drive a small turbine which generates electricity. There are not many working examples of this in Australia but there has been a lot of research into it. Solar hot water falls into this category also.
Advantages of using solar energy
- It's almost free once the equipement is installed.
- Energy from the sun is renewable (it won't run out).
- It is very useful for remote areas that are not connected to the main electricity grid.
- It is environmentally safe (ie it produces no greenhouse gases).
- Australia has heaps of sunshine!
Disadvantages of using solar energy
- It doesn't work well on days when it is overcast or cloudy and it doesn't work at all at night.
- Solar generators are expensive and require a lot of space.