Contrary to what some people think, solar panels placed in the hot sun are less efficient in producing electricity than those in cold climates. Solar panels need only light to produce electricity; heat reduces their efficiency. Therefore, in India, the best place to put up a solar plant is the cold Ladakh region, where there is plenty of light and practically no heat.

But Ladakh is far away from concentrations of population. Rajasthan, Gujarat and Tamil Nadu are solar hotspots (pun intended). However, when the panels heat up, down goes their capacity to produce electricity.

Now, a solution may be at hand. Scientists at the Hong Kong Polytechnic University have figured a way to make the panels sweat out the heat and keep cool.

All they did was smear a gel over the panels.

But the technology lies in the gel, which is a cocktail of carbon nanotubes, polymers and calcium chloride. This material sucks in water vapour from the air during the cool nights, when humidity is high. When the sun shines the following day, the gel releases the water in the form of droplets, which quickly evaporate — leaving the gel ready for another round of work in the night. The evaporation cools the panels. The scientists have found that the cooling effect is better when it is windy.