Write explanatory note on solar energy | Discuss present status as well as future prospects along with merits and demerits of solar energy in India

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Q. Discuss present status as well as future prospects along with merits and demerits of solar energy in India. (R.G.P.V., June 2013)

Ans. As our reserves of coal, oil and gas will last only for few more years and nuclear energy involves considerable hazards, solar energy can be a very important source of energy. Since sun is expected to be radiate at this constant rate for a few billion years, it can be regarded as almost an inexhaustible source of energy.

In India, where sun keeps shining in most of the part for almost entire year solar energy can be of very much importance. Indian Government recognized this source of energy and developed a Solar Energy Centre under the Ministry of Non-conventional Energy Sources. Its activities include R & D on solar heating, solar thermal power generation, solar passive architecture and green house technology. In India, 10000 domestic and 5000 industrial solar water heating systems; 2.25 lakh solar cookers, 10000 solar stills are in operation. Department of Metallurgy, College of Engineering, Pune designed a solar

furnace that can generate a temperature of 2000°C and can be used for surface

hardening of steel and cast iron, etc. A solar thermal power plant of 22 kW capacity using focused collectors and steam turbines, is in operation at Solajipally village in Andhra Pradesh. Another plant of 50 kW is under installation at Twal Pahari Premisses of the Solar Energy Centre, Gurgaon, Haryana.

Solar photovoltaics (SPV) systems are used for powering a number of rural and remote areas.

A solar pond has been designed at Bhuj, Kutch district of Gujrat to supply 220 lakh kWh of thermal energy per annum, about 1,25000 kWh of electricity per annum and about 80000 liter of potable water per day.

Merits -

(i) Solar energy is the most potential renewable source of energy. If we can utilize only 5% of total solar energy, it can fulfill our energy requirements for 50 times.

(ii) This is almost inexhaustible source of energy as, sun will continue to radiate for billions of year.

(iii) This is the pollution free source of energy. (iv) It is the cheapest of all renewable sources.

(v) In remote areas, where conventional energy is not available, solar energy can be quite useful.

Demerits-

Despite all the merits, solar energy has certain limitations to its use for extensive applications, which are-

(i) The intermittent and variable manner in which solar energy arrives at earth's surface.

(ii) Large area required to collect solar energy at a useful rate.

(iii) Its non-availability on rainy days and in nights, requires an auxiliary back-up system.

Q.39. Write explanatory note on solar energy. (R.GP.V., Dec. 2016)

Ans. Solar energy is the energy produced and radiated by the sun, more specifically, the sun's energy that reaches to the earth. Solar energy which is the primary source of all kind of energy on the earth, originates in the sun as a result of thermonuclear fusion reaction. Sun can be considered as a large sphere containing helium gas, which is continuously producing hydrogen through fusion reactions and liberating a large amount of heat energy. This energy is radiated by the sun in the form of electromagnetic radiations of which 99% having their wavelengths in the range of 0.2 to 0.4 µm. Solar energy received in the form of radiation can be converted directly or indirectly into other forms of energy, such as heat and electricity. Solar energy keeps the temperature of earth above that in colder space, causes air currents in atmosphere and water current in oceans, causes the water cycle and helps in photosynthesis in plants.