How to make the solar mission possible
Jeffrey Grossman, an associate professor of power engineering at mit, is playing with the Japanese art from origami. He is not an artist but is developing new shapes for solar modules made of solar cells, the key component converting sun rays into electricity. Grossman has also taken inspiration from biological evolution and developed a 54-W module two-and-a-half times more efficient than conventional ones.
Companies and researchers are thinking of ways to efficiently harness solar power. Their aim is to achieve grid parity and beat cheap coal-based power. India also wants to achieve grid parity by 2020, and it hopes to bring down the cost of solar power by 2026 to that of coal. For that technology will need to leapfrog. The first phase of the national solar mission will only experiment with technology. “Only for the second and third phase will the government draw a strategy to reduce the cost of producing solar power,” said an official of the Ministry of New and Renewable Energy.
More than 90 per cent of solar installations in India use crystalline cells made of silicon wafers, but in India the efficiency of crystalline cells is 12-18 per cent. According to the ministry, the highest efficiency in converting solar energy to electrical achieved by an Indian company is 19.7 per cent. The technology, developed by the government-owned Central Electrical Laboratories in Ghaziabad, is not commercially available. International companies are commercially producing solar cells with over 19 per cent efficiency. Chinese manufacturer Suntech is selling cells with an electricity conversion rate of 19.2 per cent. Another photovoltaic module maker Sunpower of the US has commercially made available cells with 20.4 per cent efficiency.
But the future may not lie in silicon. One of the most promising technologies is multi-junction cells comprising several layers of semiconductors. Unlike single-layer crystalline silicon cells, which catch a fraction of the spectrum of the sunlight, their layers trap the entire spectrum. The Mars rover is using multi-junction cells. If the sunlight is concentrated on the multi-junction cells their efficiencies reach up to 50 per cent.
In India research on multi-junction cells is next to negligible. The ministry has recently tied up with a few institutions for such research.
One of the key areas where India needs to invest in the short term is meteorological stations that monitor solar radiation. Currently, 45 of the 200 weather stations of the India Meteorological Department (imd) have installed radiation monitoring equipment. “Most of these stations are in big cities, but the industry would require much more accurate data at the village and block level,” said Deepak Verma of Emergent Ventures, a renewable energy consultant. Currently, solar power producers are using data prepared by international agencies which is compared with imd data wherever possible. imd officials agree their data is not sufficient. “Radiation might not be uniform in the region covered by a particular station. Radiation is also not uniform throughout the day,” an official said. “Each plant may need a radiation monitoring station for itself.”