Recent advances in photovoltaic thermal collectors (PVT): from conventional designs to high insulation glazing and semi-transparent PVT for building applications

Photovoltaic Thermal (PVT) systems offer the potential to simultaneously generate electricity and heat from solar energy, achieving significantly higher overall efficiencies than standalone Photovoltaic (PV) or solar thermal collectors. However, despite decades of research since the 1970s, real-world adoption of PVT technology in buildings remains limited compared to separate PV and thermal systems. Prior studies have predominantly focused on improving the performance of conventional opaque PVT panels as standalone systems. Meanwhile, the integration of high insulation glazing in PV and PVT, as well as Semi-Transparent PVT (SPVT) collectors for building applications, remains underexplored. To address this gap, this paper traces the development of PVT systems, beginning with conventional opaque technologies, followed by developments in high-insulation glazing applied to PV and PVT collectors, and concluding with a review of SPVT systems for building integration. To achieve this, the review begins with an overview of PVT innovations published between 2020 and 2025, followed by a focused analysis of high-insulation glazing technologies for PV and PVT (2018–2024), and concludes with a detailed discussion of SPVT advancements (2014–2025). This review identifies a critical gap in the literature: to date, most building-integrated SPVT research has focused mainly on dual functionality (electricity and heat), despite its potential for optical daylighting. Furthermore, no studies to date have investigated real-scale implementation, SPVT–glazing building integration, detailed technoeconomic assessments, or standardized performance evaluation methods for optical, thermal, and electrical outputs. This review highlights these knowledge gaps and recommends future research directions to advance multifunctional solar technologies for energy-efficient buildings.