Integrated photovoltaic–thermal solar collectors have become of great interest in the solar thermal and
photovoltaic research communities.
Solar thermal systems and solar PV systems have each advanced markedly, and combining the two technologies provides the opportunity for increased efficiency and expanded utilization of solar energy.
In this article, the authors critically review photovoltaic–thermal solar collectors for air heating. Included is a review of photovoltaic thermal technology and recent advances, particularly as applied to air heaters. It is determined that the photovoltaic–thermal
(PV/T) air heater is or may in the future be practicable for preheating air for many applications, including
space heating and drying, and that integrated PV/T collectors deliver more useful energy per unit collector
area than separate PV and thermal systems. Although PV/T collectors are promising, it is evident that
further research is required to improve efficiency, reduce costs and resolve several technical design
issues related to the collectors