Solar Energy

These notes are based on the chapter Sources of Energy of class 10 NCERT book and CBSE syllabus.

Energy from the sun, converted into thermal or electrical energy is called solar energy or solar power.

The sun is the main source of energy for all living beings on this earth. Even the energy in the fossil fuels has come from the sun. The sun has an endless reservoir of energy which would be available as long as the solar system is in existence. Technologies for harnessing the solar energy have been developed in recent times.

Flat Plate Collector

A flat plate collector captures solar energy and converts this energy into heat energy. The heat is transferred to air or water which is called carrier fluid. The heat from the carrier fluid can be used directly or can be transferred to another medium.

A flat plate collector is composed of a blackened metal plate and a mirror. The blackened metal plate absorbs most of the heat falling on it.

Solar Pond

A water body containing saline water is generally used as solar pond. Saline water absrobs heat from solar radiation. This heat is then utilised for various purposes.

Solar Cooker

Solar cooker is very simple in design and mode of function. It is usually made from mirrors. Plain mirrors are placed inside a rectangular box. The light reflected from the plain mirrors concentrates the solar energy inside the solar cooker which generates enough heat to cook food.

Solar Furnace

Solar furnace is made like a concave mirror. Large solar furnace has many smaller mirrors to compose a very large convex mirror. The thing to be heated is place near the focus of the mirror.

Solar Cells

Solar cells are made from silicon. Solar cells are also called photovoltaic cell. The solar panel converts solar energy into electrical energy which is stored in a battery; for later use.

Working of Solar Cell

A solar cell is composed of layers of antireflective matter, transparent coating, glass coating; followed by layers of semiconductors. When sunlight hits the junction between a semiconductor and a metal or between two semiconductors then a small electric voltage is generated. This is the concept behind working of a solar cell.

Advantages of Solar Energy

• This is a non-exhaustible source of energy
• This is an environment friendly source of energy
• With developments in technology, harnessing solar energy is getting cheaper

Limitations of Solar Energy

The technologies for harnessing solar energy are at a nascent stage. At present, the cost benefit ratio for using solar energy is not conducive. Using solar energy is very costly.

• Cost of photovoltaic panels is very high.
• Solar energy can be harnessed only at places which get good amount of sunshine.
• Solar energy cannot be harnessed during winters and on cloudy days.
• Solar energy cannot be harnessed during night.