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Solar Energy Hotspots

Space scientists have used satellite data to generate a map displaying the country’s most promising sites to harness solar energy, marking “hotspots” in western, central and southern India with abundant sunshine and ideal for investments to expand solar power. The scientists at the Space Applications Centre (SAC), Ahmedabad, have identified regions in Gujarat, Rajasthan, Madhya Pradesh, Karnataka, Tamil Nadu, and Chhattisgarh that they say could yield assured solar energy between 2,500-3,500kWhour per square meter per year.

One kWhour is the energy consumed by ten 100-watt bulbs lighted for an hour.

“If these estimates are correct, these regions promise solar energy investors more than double the average (solar) energy available in India,” said Rajinder Kaura, vice-president of the Solar Energy Society of India, an association of solar energy developers and users, who was not associated with the SAC exercise. India has an installed cumulative solar power capacity of about 7,600MW, with the largest contributions from solar energy projects in Rajasthan, Tamil Nadu and Gujarat, but the Narendra Modi government has pledged to expand this to 1,00,000MW by 2022.

At the SAC, remote sensing specialist Bimal Bhattacharya and his colleagues used Kalpana-1, a meteorological satellite launched by the Indian Space Research Organisation in 2002, to examine solar radiation over India over a three-year period – 2009 through 2011. Their analysis has helped them mark separate solar energy potential zones with the most promising pockets in western and central India, including Chhattisgarh, followed by areas along the Indo-Gangetic plain where the estimated solar energy potential varies from 2,500-1,500kWhour.”Our map provides solar energy potential estimates for India in higher resolution (detail) than have been available until now,” Bhattacharya told The Telegraph. “We’re hoping they will guide the central and state renewable energy departments and companies investing in solar power.”

The analysis by the SAC team has been accepted for publication in Current Science, a journal published by the Indian Academy of Sciences. Although the SAC-generated map identifies new areas with nearly as much solar energy potential as Gujarat and Rajasthan, industry representatives believe the focus on these two states will persist. “Gujarat and Rajasthan have abundant sunshine and the cost of land there is relatively low,” Kaura said. The solar energy community in India has traditionally relied on a sparse network of 45 solar radiation measuring stations across the country. The Union ministry of new and renewable energy is set up a network of 121 solar radiation resource assessment stations, but even that will remain inadequate.

While current estimates of solar radiation depend on daytime temperature variations, sunshine hours cloud cover, rainfall and humidity observations, these approaches cannot take into account the influences of key atmospheric parameters such as water vapor, ozone, and cloud.”Satellite-based estimates can take into account such atmospheric influences on the radiation,” Bhattacharya said. While solar energy estimates have been available from US satellites, SAC scientists say Isro’s Kalpana-1 satellite provides estimates at a resolution of 8km over India, thus in finer detail than available from foreign satellites.

“A map from the Space Applications Centre could be a new, credible source for data for the solar energy developers’ community in the country,” said Pranav Mehta
, the chairperson of the National Solar Energy Federation, an umbrella body of manufacturers, engineering companies and financial institutions in the solar power business.

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