Renewable Sources Of Energy


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       We have studied that sunlight consists of infra-red rays. The heat of infra-red rays can be utilized to do some useful works by preparing suitable devices. Those devices which directly utilize solar energy to do some useful works are called solar energy devices. Solar cookers, solar cells, solar water heaters, solar furnaces, solar thermal plants etc. are examples of solar energy devices.

Limitations or Drawbacks of Solar Heating Devices

  1. The main drawback of solar heating devices is that there efficiency is very low as compared to those devices which run on electricity. The reason for it is that all the solar heating devices depend on sun light for their working. But, the sunlight reaches the earth in much diffused form. Also a large amount of heat absorbed from sunlight by solar heating devices is lost by the process of conduction, convection and radiation.

  2. The second drawback of solar heating devices is that they cannot be used to cook food during night and rainy days when the sky is covered with clouds.

  3. The third drawback of solar heating devices is that the direction of their reflectors has to be changed after short intervals of time of keep them facing the sun.

Solar Cookers

       A solar cooker is a device that directly collects solar energy in the form of heat and is used to cook food. These days, more and more people are using solar cookers to cook their food as the prices of conventional fuels are increasing at a very fast rate. Also the food cooked in a solar cooker rarely burns and its nutrients are not lost.

Types of Solar Cookers

       Two major types of solar cookers are:

  1. Box type solar cookers and

  2. Solar concentrators or spherical reflector type solar cookers

Test Your Understanding and Answer These Questions:

  1. What are solar energy devices?

  2. What are solar cookers?

  3. What are types of solar cookers?

  4. What are drawbacks in solar heating devices?