Comparative numerical analysis of 11 low-cost single-pass photovoltaic/thermal solar collectors for air heating

Abstract In the context of a growing demand for sustainable energy, air-based photovoltaic-thermal systems offer a promising solution for the simultaneous production of electricity and heat. This work aims to identify the optimal configuration of a low-cost, single-pass air-based photovoltaic-thermal system capable of producing hot air for certain activities in the Safi region (Morocco), such as drying agricultural or marine products, heating buildings, or air conditioning greenhouses, while ensuring electrical autonomy. The study is distinguished by a systematic investigation of an extended set of candidate air-based photovoltaic-thermal configurations (11 in total). 3D simulations were carried out using COMSOL Multiphysics under identical conditions: solar irradiance of 1000 W/m2, inlet/ambient air temperature of 30°C, wind speed of 1 m/s, a fixed collector tilt of 32°, and air mass flow rates of 30, 60, and 90 kg/h. Under these conditions, the unglazed UG2 and UG4 configurations achieve the highest electrical efficiencies (≈17%), while UG5 yields the highest overall exergy efficiency (≈19%). G6 stands out by delivering the highest thermal efficiency (≈25.6%), the highest overall energy efficiency (31.04–38.35%), and outlet air temperatures above 50°C, while maintaining a satisfactory electrical efficiency (≈13%). G6 also attains the highest Type II overall energy efficiency (50.22–64.00%), indicating greater primary energy savings potential and, consequently, the largest associated CO2 reductions. Aligned with the study objectives, G6 is best suited to autonomous thermal applications, while UG5 is preferable when electricity production is the overriding priority.