Solar Energy

The exploitation of solar energy has been one of the major programs. Solar energy, which is manifested in the form of heat and light, is harnessed through solar thermal and solar photovoltaic (SPV) routes for applications like cooking, water heating, drying farm produce, water pumping, home and street lighting, power generation for meeting decentralized requirements in villages, schools, hospitals, etc. In spite of the limitations of being a dilute source and intermittent in nature, solar energy has the potential for meeting and supplementing various energy requirements.

India, being a tropical country, is blessed with plenty of sunshine. The average daily solar radiation varies between 4 to 7 kWh per square meter for different parts of India. There are on an average 250 to 300 clear sunny days a year. Thus, it receives about 5,000 trillion kWh of solar energy in a year. It is environment friendly and is freely available locally.

Though the energy density is low and the availability is not continuous, it has now become possible to harness this abundantly available energy very reliably for many purposes by converting it to usable heat or through direct generation of electricity. The conversion systems are modular in nature and can be appropriately used for decentralised applications. As a result of sustained research and development, several technologies have already been commercialised while some technologies are still under development.

The main objectives of the solar thermal program are to develop and promote the use of these technologies in order to meet the heat energy requirements in domestic, institutional and industrial sectors in India and also to generate electricity in an environment friendly manner. For harnessing the enormous potential of solar energy, MNRE is implementing a variety of programs in India.

Solar Photovoltaic Program

As a result of development and deployment of PV technologies for more than two decades, a strong research infrastructure and a good manufacturing base for production of single and polycrystalline silicon solar cells/modules has been established in India, which ranks fifth in the world among the PV module manufacturing countries.

Although the cost of the technology is high, it has been gradually decreasing. Today, PV technology has become cost competitive to other technologies based on conventional energy for meeting power requirements of small load in remote areas. There is a need to bring down the cost of PV modules further so that PV technology becomes commercially viable.

Under the SPV Demonstration and Utilisation Program grants in aid is given to the implementing organisations for providing subsidy to the users for purchase/ installation of solar home systems, solar street lighting systems, stand alone power plants, building integrated photovoltaics etc. The program is being implemented through the State Nodal Agencies (SNAs), selected NGOs, central public sector undertakings and ‘Aditya Solar Shops’ in India. The solar home systems have been provided to all categories of individual users and non- commercial users. The power plants are designed to provide grid quality power with better reliability to a village/hamlet or institution etc.

A total of 60,000 SPV home-lighting systems, 6000 SPV street lights and 27,500 solar lanterns were allocated to various states and UTs. 3.24 lakh SPV home lighting systems, 0.53 lakh SPV street lighting systems and stand alone SPV power plants of an aggregate capacity of 1851 kWp have been installed up to anuary 01, 2007, since inception of the programme.

Solar Grid Power program

The solar grid power program has two components- the thermal conversion technology and the photovoltaic technology. The Solar Photovoltaic technology converts sunlight into electricity without any pollution. The solar photovoltaic (SPV) program has resulted in significant technological developments for various applications.

34 grid- interactive SPV power projects with an installed capacity of 2.8 MW have been installed and 6 more projects with an aggregate capacity of 400 KW are under installation. MNRE has supported demonstration projects involving grid interactive SPV power plants. Under this program, Central Financial Assistance (CFA) in the form of grants-in-aid and subsidies is being provided to beneficiaries- State Nodal Agencies (SNAs) and SEBs for resource assessment, feasibility studies, research and development and to design, install and operate Solar Photovoltaic Power Plants in grid interactive mode.

CFA of 2/3rds of the project cost, subject to a maximum of Rs 1.2 crore for a 100 kWp system is being provided. For Special Category States i.e. North Eastern States including Sikkim, Jammu & Kashmir, Himachal Pradesh, Uttaranchal and unelectrified island regions the CFA is up to 90% of the project cost with maximum of Rs 1.62 crore per 100 kWp.

During 2004- 05, three grid interactive SPV power plants viz. 100 kWp in village Gorrir, District Jhunjhunu, Rajasthan, 50 kWp at Havelock island of Andaman & Nicobar Islands and a 25 kWp on the Chief Secretariat of Pondicherry, have been commissioned till January 01, 2005.

As solar grid power technolgies are not commercially viable, they at the present juncture serve the purpose of technology demonstration. Sufficient experience in installation, operation, maintenance and other aspects of grid interactive power plants has been gained. Present technological advances suggest that these technologies will start becoming viable from 2020 onwards. A policy decision has been taken not to support any new grid interactive SPV power plants.

During the past few years, many organisations have started using the SPV systems for varied uses like power for rural telephones, railway signalling, low power transmitters, cathode protection, etc

Water Heating

One of the areas of Solar thermal technology is heating of water for domestic, commercial and industrial uses. India has been making and using solar water heaters for almost three decades. Solar water heating systems are becoming increasingly popular. Hotels, hostels, hospitals, and other large institutions & industries have gone in for these systems. Water heating systems with a total collector area of one million sq. m have so far been installed. State Governments have been advised to make necessary provisions in buildings to incorporate solar water heating systems.

When this solar heater replaces an electric geyser, it not only saves electricity but also reduces the peak load demands. Also a domestic water heater of 100 litres capacity can prevent emissions of 1.5 tonnes of carbon dioxide every year.

Biomass Energy and Cogeneration

The availability of biomass in India is estimated at about 540 million tons per year covering residues from agriculture, forestry, and plantations. Principal agricultural residues include rice husk, rice straw, bagasse, sugar cane tops and leaves, trash, groundnut shells, cotton stalks, mustard stalks, etc. It has been estimated that about 70- 75% of these wastes are used as fodder, as fuel for domestic cooking and for other economic purposes leaving behind 120- 150 million tons of usable agricultural residues per year which could be made available for power generation. By using these surplus agricultural residues, more than 16,000 MW of grid quality power can be generated with presently available technologies. In addition, the potential of bagasse cogeneration is estimated at 5000 MWe, if all the 500 sugar mills in India switch over to modern techniques of co- generation. Thus, India is considered to have a biomass power potential of about 21,000 MW.

To tap this potential, MNRE has been implementing biomass energy/ co- generation program for the last 10 years. The program aims at optimum utilization of biomass materials for power generation or for replacement of conventional fuels through adoption of efficient and state- of- the- art conversion technologies. The technologies being promoted include combustion/ gasification/ cogeneration, using gas/ steam turbines, dual fuel engines/ gas engines, or a combination thereof, either for generation of power alone, or for cogeneration of more than one energy form, for captive and/ or grid connected applications. The Program has two main components- a) Biomass Power/ Co-generation & b) Biomass gasification.

It is well established that industries in which both process heat and electricity are needed are well suited for cogeneration of electricity. Optimum bagasse cogeneration in the sugar mills and biomass power generation from surplus agricultural residues, are being actively promoted.

The cumulative installed capacity of grid-interactive biomass and bagasse cogeneration power projects up to March 31, 2006 was 912 MW. During 2006-07, 190 MW has been installed up to January 01, 2007 and as per trends it is likely that a total of 220 MW would be added during the year. With this, the capacity addition during the 10th Plan would be 750 MW.

A few Regulatory Commissions have already come out with their formulations to promote arrangements between the co- generator and the concerned distribution licensee for purchase of power from such plants. Cogeneration system is being encouraged in a few states in the overall interest of energy efficiency and also grid stability. Notable initiatives include a biomass resource assessment program to bring out a Biomass Resource Atlas for India; facilitating fast track projects; new modes of implementation of projects in co- operative/ public sector sugar mills; and, technology development and demonstration of producer gas engines and advanced biomass gasification.

State- Wise Grid-interactive Biomass Power Installed Capacity (as on Jan 01, 2007) 

in MW

For detailed information on the Indian Renewable Energy Sector, refer to the report - 'Overview of Power Sector in India 2008 edition'