Solar power is the power obtained after harnessing the energy released by the sun as a result of fusion reactions between hydrogen nuclei taking place in its core. It is the sun’s energy which sustains all life on the earth. Plants require sunlight for photosynthesis. Animals feed on those plants. This is why the sun’s energy is so important; about 1,400 MW per minute per square kilometre are sent to the earth. Any alteration in that could result in the end of life on this planet.
Of the 1,400 MW per minute that reach the earth’s atmosphere, only less than half reach the surface. A large fraction is absorbed by the atmosphere and clouds. The amount of light available also depends on the latitude of a place in consideration.
Methods of harnessing the sun’s energy
The sun’s energy can be harnessed either directly or indirectly.
Direct solar power
Direct means of utilizing the sun’s energy involve the use of solar panels or photovoltaic cells. Photovoltaic cells, used in solar powered calculators and watches, are chemical cells that require ‘photons’ (packets of light) in order to catalyze chemical reactions in them so as to produce a voltage potential.
Another way in which direct tapping of solar energy is done is in spacecraft using solar sails. Flat plate collectors are the best examples of how solar power is used directly. Thin boxes with insulated casings, fluid tubing, circulating pumps, temperature sensors and heat sensors are provided in their assembly. Thermal collectors use direct solar radiation to exchange heat in a fluid circuit.
Many of these systems are deployed in water and space heating systems in buildings. Fibre optics can be installed to utilise the sun’s light in order to supplement lighting in buildings.
Indirect solar power
There are innumerable examples of indirect solar power.
- Photosynthesis results in chemical energy being stored in chlorophyll-rich plants. Plants are then available for food and nutrition by animals and humans.
- The fossil fuels are actually dead and decayed living matter left of the remains of ancient plants and animals. Thus crude oil, coal and natural gas are obtained, and these can be used in a huge number of ways in order to meet man’s energy needs.
- The water cycle requires a tremendous amount of the sun’s heat in order to keep itself going.
Forms of solar power – either passive or active
Solar power can be classified as passive, if no supportive power is required and as active, if outside energy is needed, for instance, in order to allow the focus of the sun to fall directly onto a panel, the panel may have to be moved in the direction of incoming energy.