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IIT Bombay Develops Solar Heat Battery to Tackle Himalayan Winters

Researchers from IIT Bombay have developed an innovative solar heat storage system to address heating challenges in the harsh winters of the Himalayan region. The project, led by Dr. Sandip Kumar Saha and Dr. Chandramouli Subramaniam, utilizes a thermochemical storage method powered by strontium bromide—a non-toxic and stable compound—to "bottle" summer sunlight and release it as heat in winter.

The system works by using solar thermal collectors to dehydrate strontium bromide crystals during summer, effectively storing solar energy. In winter, when moist air passes through the material, the reverse reaction occurs, releasing heat. A prototype module, about the size of two LPG cylinders, can store up to 500 kWh of energy—sufficient to heat a small Himalayan home for four months.

Designed for portability, the modules can be charged in sunny states like Rajasthan or Gujarat and transported to colder regions. With a levelised cost of heating (LCOH) ranging from Rs33–51/kWh—and as low as Rs31/kWh in Leh—the system is cost-effective compared to diesel-based heating, especially when accounting for transport and environmental costs.

The team sees promising applications for remote communities and the Indian army and calls for policy support to enable real-world deployment and scale-up.