An international research team has experimentally assessed five planar heat-pipe prototypes designed to cool photovoltaic modules. The devices spread heat across the rear of a module and transfer it to a compact water-cooling unit, with the aim of reducing temperature differences and hot spots.
Each prototype measured 1,650 mm by 1,000 mm and consisted of stainless-steel plates enclosing a shallow cavity filled with distilled water. The designs varied in their internal mesh and support structures, plate thickness and water volume. Researchers tested them against setups without heat pipes, using heating pads to simulate uneven module temperatures.
Tests covered natural convection at two angles and localized water cooling, with heating-pad temperatures ranging from 50 C to 100 C. Sensors and infrared images were used to assess heat transfer and temperature uniformity. Depending on the design and test temperature, peak surface temperatures fell by approximately 8 C to 32 C. Differences in thermal performance among the five prototypes were small under the conditions studied.
The team then used the measured temperature reductions in a simplified photovoltaic model based on weather data for Riyadh, Saudi Arabia. The analysis estimated that active water cooling could increase annual electricity generation by 2.2% to 3.6%. The researchers also estimated a theoretical upper-bound benefit of up to 4.5% from the heat pipes’ ability to make module temperatures more uniform.
The study, titled “Experimental evaluation of planar heat pipes with active cooling integration for photovoltaic thermal hot-spot mitigation,” was published in Renewable Energy. Its contributors were from Lappeenranta-Lahti University of Technology in Finland, Friedrich-Alexander University of Erlangen–Nuremberg in Germany, and Saudi Arabia’s Samirock.
Sources: pv magazine.