Did you know that at least 40% of electricity that is generated is lost in transmission? And all this, while the sun shines merrily on and we do nothing more than bask in its warmth.
The most common use of solar energy is to dry clothes. Solar cookers have been around for awhile and it is a treat to watch people (especially in North India) place their ‘rajma’(lentils) and ‘chawal’(rice) in the large glass cases, and have it cook as if by magic. The magic is called harnessing. Solar energy is perennial and costs nothing. The only costs are the installation and maintenance of solar panels.
HOW IT WORKS
The solar panels work in one of the two ways.
1. They may be ‘cells’ that convert light into electricity, these are called photovoltaic cells and are commonly used on terraces of households to supply energy to water heaters and other heating appliances.
2. The other method is concentrated solar power (CSP) where using mirrors or lenses, sunlight is focused into a single beam where it is used to heat up something (provide thermal energy), what our solar cookers used.
Photovoltaic cells are an arrangement of layers of a semi-conducting material like silicon. When they come in contact with light, an electric field is created across the layers. The stronger the light, the greater the electricity produced. Do you think this means that PV cells can produce electricity even in feeble sunlight or on a cloudy day?
Depending on the requirement of electricity, groups of cells are mounted on the roof. There are variations. Sometimes, solar cells are manufactured in the form of tiles, so they can be directly used on the roof instead of ordinary tiles.
The peak performance of the solar cell would naturally be when it receives direct sunlight in summer. Keeping this as the benchmark, its power is measured in kilo Watt peak (kWp).
CONCENTRATED SOLAR POWER
CSP on the other hand, is a two step process. A system of mirrors is used to focus sunlight and create concentrated high temperature heat. In step two, the heat is sent to a regular thermal power plant that generates electricity. CSP uses only direct beam sunlight and therefore not work up to its full potential on cloudy days. But it has the advantage of combining with other types of energy generation, natural gas for example, and creating hybrid power plants. CSP is typically used for large scale electricity generation like a village or even to supply to a central grid, rather than just for household use.
Solar energy is clean and almost free. Let’s use it more.
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