Physics and Technology – Solar Technology
Radiation from the sun can be transformed into useful energy without the release of harmful emissions. Much research is now being invested in developing solar technology.
The sun can be compared to a gigantic nuclear reactor. Inside the sun, atomic nuclei fuse together, releasing huge amounts of energy that then reach the Earth in the form of solar radiation. The aim of solar technology is to harness this energy and transform it so that it is useful to people. This goal is not pointless, since if the sun’s entire energy output could be put to use, around 2,500 times more energy would be available than the current worldwide demand.
The term solar technology includes various systems. Photovoltaics, for example, use the same principle as light-emitting diodes, only in the opposite direction. Absorbed light is converted into electricity using silicon-based semiconductors. Commonly used solar cells are capable of converting 8 to 16 percent of the light they capture into electricity. Solar thermal devices, however, use the sun’s energy to heat water, which is then stored in “solar batteries” (insulated water tanks).
Other technologies using solar power include solar-chemical systems, solar chimneys, and photochemical installations. The great advantages of solar technologies are their low-cost and emission-free operation. There are, however, also significant disadvantages. The life span of solar cells is only about 20 to 30 years.
Moreover, their production is costly and often dependent on government subsidies. Many countries offer private rebate incentives for the use of solar power, meaning solar cells can pay for themselves in five to ten years.
Future research and development
In the future, mirrors and magnifying lenses will be used to increase the efficiency of solar cells by sup- plying them with more light (“concentrator cells”). In addition, multiple layers of semiconductors are expected to allow solar cells to exploit a wider spectrum of light.
Using an extremely thin coating of silicon for the cells may also significantly reduce production costs.
THE SOLAR ENERGY CYCLE
Most homes with solar panels feed the power produced into the public electricity grid. Electrical devices in the home draw their electricity, as usual, from the electric utility.
This makes sense when the solar power produced has a greater value than the cost of power from the local utility. In self-sufficient “island systems,” solar power is stored directly and in batteries.
BASICS
SOLAR DEVICES are classified according to their power level. They may use several dozen watts (as in parking meters), a few kilowatts (residential systems), or several mega-watts (large “solar parks” or arrays of solarpanels).