Solar energy can show the way to decentralisation of energy use. Most parts of the country have about 300 sunny days, with average solar radiation incidence ranging between four to seven kWh a day. Unfortunately the country has not been able to tap enough solar energy to meet its needs.
The present total installed power generation capacity in the country is more that 1,35,000 mw. But there is a large gap between the demand and supply position. India is a vast country with an area of over 3.2 million sq km and a population of over one billion people. Several experts have said that use of various renewable sources of energy, approach for decentralised power generation and distribution and a judicious energy mix use can solve the energy needs of the country to a great extent.
Solar photovoltaic (SVP) technology enables direct conversion of sunlight into electricity. A number of solar photovoltaic cells joined together make a solar photovoltaic module necessary for harnessing energy. A combination of solar modules in series or parallel combinations, storage battery, interface electronic, mechanical support structure, cable and switches constitute a solar photovoltaic system.
The electrical output of a SPV module is rated in terms of peak watt (wp) which is the maximum power output that SPV module can deliver under standard test conditions of incident solar radiation of 1,000 watts per sq metre are, spectral distribution of solar radiation as air mass 1.5 and measurements being made at 25 degree C ambient temperature. A SPV system can be used to provide electricity for lighting, water pumping, battery charging. Some of the advantages of SPV systems are the long-life time, reliability, no recurring needs for fuel, low maintenance and zero pollution.
According to the union ministry for new and renewable energy sources during the last three decades, some efforts have been made for development and evolution of SPV technology and its deployment in the country. Some SPV systems and products are now commercially available which offer an economically viable solution as compared to the use of fossil fuels in certain situations.
Though, according to the government, India today has among the world?s largest programmes for deployment of decentralised SPV systems, the achievement figures show a lot of untapped potential. The cumulative grid-interactive solar power generation has been only 2.12 mw till the end of the previous year. Among decentralised approach to power generation and distribution 69,549 solar street lighting system, 3,63,399 solar home lighting systems, 5,85,001 solar lanterns, 7068 SPV pumps have been installed. About 268 Aditya Solar Shops have been opened. Some solar plants installed could generate 2.18 megawatt peak (mwp) power on cumulative basis till the end of the previous year. The total cumulative SPV power generation has been only 110 mwp against a potential for 20 mw per sq km.
Solar thermal energy technology is another way of harnessing solar power. When incident sunshine is captured and transferred as heat to perform various useful activities, it is called as thermal application of solar energy. Depending on the technology, the temperature of the output thermal energy can vary from as low as ambient temperature to as high as 3,000 degree C.
This opens up a vast area of applications including water/air heating, cooking, drying of agricultural and food products, water purification, detoxification of wastes, cooling and refrigeration, heat for industrial processes and electric power generation. Solar architecture for designing of energy efficient buildings based on the concepts of solar energy is an important emerging application.
However, solar thermal programmes have progressed at a slow pace. Achievement on cumulative basis for solar water heating systems has been in only 2.15 million sq metre collector area as against the assessed potential for 140 million sq metre collector area. Only 6.17 lakh solar cookers have been distributed so far.