Hybrid Solar PVT Systems for Thermal Energy Storage: Role of Nanomaterials, Challenges, and Opportunities

Abstract

Spectral splitting of CPV/T (concentrated/photovoltaic thermal) system utilizes the full range of solar radiation to obtain useful energy by coupling solar cells and other thermal absorbers. The PCM coupled with PV/T systems can absorb the heat from solar cells and allowed the PV/T systems to operate at low temperatures. Furthermore, the potential use of PCM and nanofluids with PV/T systems to improve the thermal and electrical efficiency was investigated. The integration of PCM with PV/T systems for building heating, HVAC, desalination and drying applications has been highlighted. The heating COP (coefficient of performance) of build-in PCM with PV/T system can be 70{\%} higher than the conventional air-conditioning systems, and the overall efficiency was about 75.49{\%}, 17.77{\%} of electrical and 55.76{\%} of thermal efficiency. The heat storage capacity of hybrid nanomaterial-based eutectic salts acts as a storage medium for energy storage applications are compared and reviewed. The role of the nanomaterials in terms of optical properties, thermal properties, long-term stability and cost will be discussed, which will guide future research and innovation. Utilizing the full solar spectrum is desirable to enhance the conversion efficiency of solar cells in combination with solar thermal collectors and photovoltaic collectors (PV) for electricity generation as a hybrid system despite their advantages and disadvantages. The spectral splitting plays a key role in any hybrid or coupled systems, as PV works under spectrum rays and thermal collectors work under infra rays. Thus, optical and thermal design of PV and thermal collectors is required to improve the efficiency of the system. Hence, the hybrid PV thermal (PV-T) collectors can generate electricity and heat energy simultaneously. Finally, the basics of PV-T collectors and the feasibility studies of two novel applications of PV-T collectors (solar cooling and solar still) have been analysed.