The operation of an HVAC system to keep interior spaces cool can be extended to take the heat off solar photovoltaic (PV) panels. An international research group tapped an opportunity to use cold air exhausted by HVAC units to cool off solar panels and improve array performance.

Cooling is achieved through the forced convection of exhaust air on the rear sides of the panels, which serves to absorb excess heat through heat transfer. The operating temperature of the PV array will be reduced due to the heat transfer between the air flow and the lower surface of the PV system, which usually has a high temperature.

The exploitation of HVAC exhaust was tested by thermal modeling on an experimental PV panel with ceria-doped glass, optical-grade adhesive, a thin silicon layer, a solder layer and an aluminum nitride substrate. Parametric assessments were also conducted by varying the cooling load of the HVAC system from 0 kW to 110 kW, with ambient temperature is set at 25° C and exhaust air temperature set to 22° C.

PV module efficiency was demonstrated to increase from 11% to 18% when the cooling load increased from 0 kW to 140 kW.

Scientists from the International University of Beirut, Lebanese International University, University of Nantes (France), Lebanese University and University Paris Diderot contributed to this research, which is published in Case Studies in Thermal Engineering.

Proposed system for cooling PV array and its corresponding thermal circuit. Source: Mahmoud Khaled et al.