Scientists from the Guwahati Indian Institute of Technology have developed a photovoltaic thermal module, the total efficiency of which can reach 79.6%.

"The water-based system produces hot water of sufficient temperature for domestic use," said researcher Dudul Das.

The researchers built a system with a 100W solar panel, a absorber with a rectangular spiral configuration using copper tubes with a diameter of 7.9 mm and a PKM based on biocoal derived from aqueous hyacinth for the cooling system.

Then they insulated the panel with a layer of foamed polyethylene and installed a plexiglass back cover to protect the system from moisture, dust and wind. They used a field-emission scanning electron microscope to analyze surface morphology, powder X-ray diffraction (XRD) to assess crystallinity and identify the phase transition, as well as a thermal conductivity meter to assess the thermal conductivity of the composite material.

The panel showed the best thermal efficiency when testing in outdoor conditions with an angle of inclination of 26 degrees.

"The application of the PKM-biocoal mold-resistant composite has successfully adjusted the thermal power of the PVT system. Thermal efficiency even after a decrease in solar radiation remains closer to 50%, while without PCM it drops to 38%," scientists said.

They found that the thermal efficiency of the panel varied from 60.3% to 71.2%, and its electrical power was 18.4% higher than that of a reference photovoltaic panel without a thermal unit.