Researchers in Spain dug deep to design a cooling system for solar panels. An underground, single-phase, closed-loop heat exchanger circuit acts as a natural heat sink and prevents overheating of photovoltaic components.

Installed in a borehole at a depth of 15.5, the water-filled, 18 mm diameter single U-shaped copper tube was demonstrated in outdoor tests to reduce panel temperatures of an array consisting of two 270 W modules by up to 17% and improve solar panel performance by about 12%.

A heat exchanger serves as a heat sink. Source: University of AlcaláA heat exchanger serves as a heat sink. Source: University of Alcalá

The cooling technique devised by researchers from Universidad de Alcalá and Ingeniería Industrial Ibérica S.A. involves the application of a heat exchanger onto the back side of a solar panel to remove excess heat. This heat is transferred underground by coolant fluid at a flowrate of 1.84 l/min per square meter of solar module and is refrigerated by another U-shape heat exchanger placed in the borehole and filled with water from a local aquifer.

The underground heat exchanger described in the Journal of Solar Energy Engineering could enable the solar energy system tested to produce 152 Wh more than its uncooled counterpart.

To contact the author of this article, email shimmelstein@globalspec.com