In an effort to reduce water usage in solar plants, the Ministry of New and Renewable Energy (MNRE) has asked the states and the solar industry to “preferably” use robotic cleaning and other new technologies for cleaning solar panels.

“The excess usage of water, sometimes, leads to wastage of the precious resource and it can be avoided through judicious usage,” the letter from the MNRE, reviewed by FE, addressed to all state principal secretaries and solar associations said.

Though water consumption levels in solar plants — roughly about 100 litre for 1,000 units of electricity — is 22 times lower than thermal power plants, water procurement is nonetheless a considerable operational burden as solar units are usually located in remote, arid regions with acute water shortage. On top of that, it puts additional water pressure in the top five states which account for 70% of total installed solar capacity.

For plants which use surface water, the annual cleaning cost can be as high as Rs 1 lakh for every MW of installed capacity. With solar developers having compromised on their margins by quoting low tariffs to bag projects, the rising costs of water threaten to further hurt the profitability of several projects. Some solar developers in Rajasthan have seen water costs almost doubling in 3-4 years. In Karnataka, tariff for industrial water usage was hiked 100 times in 2018. Significantly, cleaning costs can comprise 25-35% of the operational and maintenance costs of a plant.
According to a study by renewable energy research firm Bridge to India, about 60% of the water used for solar panels is procured through bore-wells.

The study recorded ‘very high’ water consumption at plants in Rajasthan, UP, Gujarat, Punjab and Haryana, where a quarter of India’s installed capacity is located. Tamil Nadu, Karnataka and MP, with 38% of solar plants, have ‘high’ water consumption levels.

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