Power from solar photovoltaics has already been shown to be cost effective in India for many applications when it is deployed at distance 4-40 km from the transmission network. Solar photovoltaic is one of the interesting possible ways for meeting the electrical energy needs of remote villages in India, having no access to utility grids. Constraints:Even at the low efficiencies associated with current technology, photovoltaic devices requirelittle land relative to other sources. The materials intensity is low compared with other alternative energy sources, although it is higher than that of conventional technology.
Studies of material availability of cell inputs, have shown that the elements of silicon, zinc, copper, tin, sulfur and phosphorous impose no limits on photovoltaic cell production. The primary emphasis of current R and D work, with single-crystal silicon, is on reducing the costs of preparing materials. Thin-film, continuous ribbon technology offers promise of very low cost cells. At present, thin film cells have efficiencies below 9 percent.
Both, cost reduction and efficiency improvements, are viewed as equally probable components in the move toward economic viability. Studies have shown concentration to be on economic option until the year 2000, when higher cell efficiencies will prove low concentration system to be less costly. Tracking has been considered to be uneconomical because of the use of diffuse as well as direct insolation. Wind Energy:Because of the comparatively long term experience in the use of wind plants, future contributions and cost of this source are more certain than those of other renewable sources. In projecting the significance of Wind Energy conversion-system’s contribution, as an energy source, account must be taken of the highly localized quality of the wind resource.
Although the resource is large, site selection is a critical and limiting factor in forecasting potential. The annual-average hourly-mean wind-speed is, generally, used to reveal the wind energy potential for a particular location. In India, at most places, this falls in the range 9-17 km/h. The rated wind speed at which full rated power is generated is normally higher than the annual average-speed. Therefore, in order to maximize energy availability during a year, a rated speed in the range of20-25 km/h would correspond to 9-17 km/h annual average-speed. The number of hours during any year, when wind speed would equal or exceed this rated wind speed at a given place, would probably be between 1000-2000 hours, though not equitably distributed throughout the year. During the period March to August, the winds are uniformly strong over the whole of Indian peninsula except the eastern peninsular coast. The months of May, June and July account for nearly half of the annual energy availability.
Wind speeds during, November to March, are weaker. Therefore, unless the wind energy availability age the demand are matched, a wind mill designed to operate in windy months world deliver only a fraction of output in the less windy months or if it is designed to operate in a less windy months, it would utilize only a fraction of energy available during the windy season. It has been estimated that in windy areas (18-20 km/h), the potential for wind power generation is about 5 MW/sq km and, in less windy areas (15-18 km/h), about 2 MW/sq km. Such wind conditions, according to the present information, are available in, at least, 5 percent of the land area of the country. On the basis of available wind information, it is estimated that there exists a potential of the order of 20,000 MW in the country for wind generated electricity. Wind and Solar energy cannot be a replacement for the presently available commercial sources of energy, in terms of the total power delivered. They can play an important role as a decentralized source, in regions where commercial power is not available and where good wind and sunshine prevail, particularly in the development of integrated energy systems in many rural areas in India.