Chinese scientists unveil a hydrogel cooling layer that boosts solar power output by 13%

In hot, sunny regions, solar panels face an invisible enemy: heat. Leaves, bird droppings, dust, or tiny defects can create “hotspots” on solar cells—small overheated areas that reduce efficiency, accelerate ageing, and in rare cases even trigger fires.

For years, this problem has limited how much power solar panels can truly deliver, especially in tropical and equatorial regions.

Now, a research team from Hong Kong Polytechnic University, Tianjin University, and Hebei University of Technology may have found an elegant solution.

They’ve developed a transparent hydrogel cooling coating that can be applied directly to solar panels. In tests, this thin layer boosted power output by up to 13% compared to conventional photovoltaic systems.

Even more impressive, it reduced hotspot temperatures by as much as 16°C (nearly 30°F)—a dramatic drop that directly translates into better performance and longer panel lifespan.

Why does this matter so much? Because for every single degree a solar panel heats up, it loses around 0.4–0.5% of its efficiency.

Studies show that more than one-third of solar panels experience overheating issues, with affected areas averaging temperature spikes of over 21°C. Over time, that heat silently eats away at clean energy production.

The secret lies in the material design. The hydrogel is made from polyacrylamide, reinforced with hydroxyethyl cellulose for strength.

Cotton threads woven in a leaf-like pattern help channel water toward the hottest spots, ensuring even and sustained cooling. On top, a thin porous layer of polytetrafluoroethylene—better known as Teflon—keeps dust away while carefully controlling water evaporation.

Cost is always the big question. Adding the hydrogel increases panel costs by about 10.7%, but in places with high electricity prices and abundant sunlight, such as Singapore or Hong Kong, the payback period could be as short as 3 to 4.5 years.

In regions with lower electricity prices, the return takes longer, though researchers expect costs to fall as production scales.

Most importantly, this technology is tailor-made for hot regions near the equator, including Southeast Asia and southern China—exactly where solar power potential is enormous but heat has been holding it back.

If widely adopted, this cooling coating could help recover up to half of the power losses caused by hotspots, pushing solar energy one step closer to its full potential.