Various uses of solar energy


by H. Saha


WITH a land area of over 3.2 million square km and a population of 900 million people, India receives solar radiation amounting to over 50X1015 kwh per year with daily average energy varying between 4 and 7 kwh/m2 depending on the location. With over 80,000 villages still to be electrified and about 70 millions households without conventional electricity connections; there is immense scope and potential for the use of solar photovoltaic technology in India.Recognising the importance of photovoltaic ( PV) technology, the Indian government has been implementing a comprehensive programme covering R&D, demonstration, commercialisation and utilisation aspects for over 15 years. The technology for the fabrication of solar cells using single crystal silicon wafers has already been developed and commercialised in that country. A five-year National Solar Photovoltaic Energy Demonstration (NASPED) programme was implemented from 198085 to bring this technology to a stage of commercial production and also develop and demonstrate various possible application. This was followed by further demonstration of the applications in different sectors and development of newer technologies such as amorphous silicon.

The major objectives of the PV programme in the 8th Plan are :

i) To continue R&D and engineering efforts with a view to lowering the cost of production and increase the efficiency of SPV systems; ii) To strengthen and intensify R&D on emerging technologies; iii) To enhance the capability for new systems; iv) To enhance the production capacity for materials, devices and systems; v) To popularise the use of SPV systems and seed the market through a well coordinated utilisation programme, taking into account the real economic costs of conventional energy systems which can be replaced or supplemented by SPV systems. vi) To establish necessary infrastructure for the installation, maintenance and monitoring of SPV systems and organise related training programmes.

An outlay of Rs. 90 crores was envisaged for the programme during 8th Plan toward support to various components of the programme. A physical target of 3 MW aggregate capacity of PV systems was envisaged. This included lighting systems, solar lanterns, water pumping systems, village power plants and other applications.Overview of the present programmeIn June 1993, MNES prepared a new strategy and action plan for accelerating the development and utilisation of renewable energy technologies. As part of this plan, the SPV programme was also significantly expanded to achieve a development level of 25 MW during the 8th five year plan through a combination of policy initiative and support to market development. Among the elements of the new action plan are :

i) Deployment of 4,00,000 solar lanterns as a substitute for kerosene lanterns. ii) Rural electrification through PV system covering 400 villages/hamlets. iii) A special programme on water pumping systems. iv) Intensified R&D on technologies which can lead to a reduction in costs. v) Commercialisation of PV systems for various applications by giving a market orientation to the programme and promoting manufacturing and related activities.

To implement the new strategy and action plan, the MNES adopted a two pronged strategy : a socially oriented programme in which the use of PV systems is promoted through subsidies and other measures, especially in rural areas; and a marketoriented programme in which soft loans and other incentives are provided for manufacturers and users. Other supporting measures include removing barriers to foreign investment and foreign technology, encouraging private investment and manufacture, reducing custom duties on imported materials and components and improving quality through provision of test facilities.As a result of these treasures India has achieved a leading status among the countries of the world in the development and use of PV technology. The Indian market and programme are the largest among developing countries. India has emerged as the second manufacturer in the world of PV modules based on crystalline silicon. Industrial production which was around 1 MW/yr before the start of 8th Plan has touched a level of 7 MW during 199495. There are over 50 companies now engaged in the production of solar cells, modules and systems. PV systems are for other specialised purposes. Export of PV products to other countries has also begun and doing well.Industrial productionThe expanding market in India for photovoltaic products has led to a substantial growth in the PV industry from an annual level of about 1 MW in the early 1990s, the production touched 8 MW of modules during 199596. About 4 MW of solar cells were manufactured in the country in 199596; the rest were imported. There are 7 manufacturers of solar cells and 13 manufacturers of PV modules in production. About 70 companies manufacture PV systems; most of these are small businesses. There is also a manufacturing capacity of about 2 million silicon wafers in India. Almost the entire production is based on single crystal silicon solar cells and India is the second largest manufacturer in the world of PV module based on this technology. Exports of photovoltaic products are also increasing with two companies exporting almost their entire production. The product exported from India are finished modules, complete systems and components such as inverters and charge controllers. The total run over of the Indian photovoltaic industry is estimated at about US$ 80 million.Solar lightingLighting is one of the basic needs in households. Lighting is also needed in shops, community centres, clinics, rural hospitals, adult education centres and in public areas such as streets. About two thirds of the households in rural areas, do not have electricity connections. It is estimated that there are about 100 million kerosene lanterns of various types in use in India. Kerosene lanterns often provide inadequate lighting, cause pollution and entail fire hazard. The MNES has been promoting the use of PV lighting systems for over a decade now. Among the systems promoted under the national programme are street lights, fixed home lighting units and portable solar lanterns.The typical solar lantern consists of a 10 watt PV module and a lantern unit comprising a 7 watt compact fluorescent lamp, a lead acid battery and a small inverter and charged controller circuit. The system provides light for 3 to 4 hours daily and can be used indoors and outdoors. Models with a 5 watt lamp and 8 and 12 and watt modules are also available.MNES provides a subsidy of about $45 on a lantern which costs about $ 120. Solar lanterns have become very popular in rural areas and in unelectrified homes. A total of over 81,000 lanterns were sold under this programme till March 1996. A further 50,000 lanterns are likely to be sold during 199697. Lanterns of other specifications are also being made and sold outside this programme.A comparison of the solar lanterns and kerosene lanterns shows that the solar lanterns give about 5 times as much light output as a hurricane lantern but costs about 50 times as much. A comparison of the life cycle costs shows that the cost of a unit of light output from a solar lantern is less than a fifth of that from kerosene lanterns if the actual cost of kerosene is take.Fixed type home lighting systems with one or two modules of 35 watts each providing power for up to 4 lights and a TV or fan are also covered by the programme. A subsidy of up to $ 170 is available on these systems. support is also provided for street lights and for small village power plants which distribute the power locally, mainly for lighting. In several parts of the country, it is found that it may be cheaper to provide lighting in villages through PV systems than through extension of the grid beyond 4 to 5 km.Among the interesting developments in recent years has been the trying out of newer ways of financing home lights and providing lighting systems in villages. In one programme implemented in West Bengal and some North Eastern states, selected village youth have been given solar lanterns and provided training on their maintenance. These youth in turn rent out the lanterns on a daily basis. Initial results show that it may be possible to use lanterns to generate employment in villages in this manner. In another case, a nongovernmental organisation has established links with rural banks to provide credit to buyers of lighting systems.Water pumpingWater pumping was one of the earliest applications of photovoltaic technology developed in India. The demand for electrical energy for running irrigation pump sets has been increasing every year leading to power shortages and restricted supply in many parts of the country. Small pumping systems with an array capacity of 300 to 360 watts were developed and tried during 1980s. Seeing the need of farmers for larger quantities of water, the MNES sponsored the development of larger capacity pumping systems fitted with efficient D.C. Motors. Separately, the Ministry also supported the trial of deep well submersible pumps.Based on the experience gained, the MNES evolved a special programme in 199394 for the supply and installation of PV water pumping systems for agriculture and related uses. Under this programme, users are offered a subsidy based on the wattage of the PV array and a soft loan towards the remaining cost of the system. Pumping systems with array capacity in the range of the 200 to 2250 watts are covered under this programme.A toll of 3000 pumps have been approved for supply under this programme so far. The programme is operated through the Indian Renewable Energy Development Agency (IREDA), which disburses the subsidy and loans to manufacturers and financial intermediaries of behalf of MNES. A unique feature of this programme is that manufacturers are required to find customers for the pumps and supply the systems to them, passing on the benefits of the subsidy and soft loan. This has led to strengthening of the marketing networks of manufacturers and helped establish a direct link between the user and the manufacturer. The performance the pumps in the field is being evaluated by the Administrative Staff College of India. 84% of the users have reported satisfaction with the systems.Power generationBesides the stand alone power plants mentioned earlier, the MNES has also been supporting experiments with gridconnected systems. A small 5 KW system was installed as a roof top system and connected to the grid at an institution in Hyderabad in 1988. Two systems of 25 kw and another of 15 kw were also installed subsequently. Most recently, an electric company in the state of Maharashtra has installed a 110 kw grid connected system. Several projects for roof top and grid supports systems are being developed. Meanwhile, some contractors have signed MoUs with the hate of Rajasthan for the establishment of 50 MW power stations.Other applicationsOver the years, MNES has started the development and demonstration of a variety of applications in different sectors. As a result of these efforts PV power systems are now being used for railway signalling, offshore oil platforms, microwave repeaters, TV transmission and reception and for providing power to border outposts of the BSF and ITBP. Many of these applications have become fully commercial, i.e. PV systems are being used by the concerned organisations at fully cost and in preference to conventional options. The largest example of this kind is in the telecommunication sector, where thousands of rural radio telephone systems are being operated with solar power by the Department of Telecommunications. There is further scope for expanding the use of PV technology by the Defence Services, Railways, Department of Post etc. The MNES is continuing to support introduction of newer applications. Among the systems proposed to be supported are refrigerators used for storing vaccines and medicines, solar water purifiers and educational kits.

Source: The Independent, 12 January 2000

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