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Surface temperature build-up due to the continuous conversion of incident sunlight to heat deteriorates the power output, efficiency, and life of photovoltaic panels. Photovoltaic-thermal (PV-T) systems provide a potential solution to avoid excessive heating of PV panels, simultaneously providing useful heat energy. A heat extraction unit is attached to the PV panel in PV-T systems that extract and convert the waste heat into useful heat. Therefore, design and material selection are keys to better performance in the system-level approach. Additionally, it is a cumbersome task dealing with refrigerant-based heat and fluid flow interactions in a system-level approach. With this in perspective, this paper analyzes different materials and flow configurations of PV-T systems. A transient, three-dimensional turbulence solver coupled with heat transfer through solids and liquids physics is modeled using COMSOL Multiphysics software. R-32 refrigerant acts as the heat transfer fluid in the system loop. The conservation equations are discretized using the finite element method. The present study involves two different plate materials (aluminum and copper) and three flow configurations (serpentine, roll-bond, and spiral) with and without absorber plates. A total of eight different configurations are being investigated here. The obtained results suggest that with the absorber plate, the performance increases significantly with a PV panel temperature decrease of 4–5 K, and the outlet fluid temperature increase by 2–8 K. It was observed that the performance difference between copper and aluminum plate is minimal (2%). Roll-bond flow configuration has scope for further research since it is more efficient than others because of the larger contact area for heat transfer.

Interfacial evaporation is known to boost the evaporation rate compared to conventional bulk evaporation, as energy conversion and vapor generation simultaneously occur at the air–liquid interface. This work presents the investigation details on the design, fabrication, and testing to determine the performance of a floating absorber structure with the sole interest of maximizing the evaporation rate. Polyvinyl alcohol cloth is the wicking cum absorber material, while extruded polystyrene sheet is the floating structure cum thermal insulator. Phase I of the study involves the comparative study between bulk and interfacial heating and the effect of different types of patterns with the same area on interfacial heating with a single absorber. Phase II involves the effect of multiple absorbers on interfacial evaporation. To identify a better design, different absorber configurations (single, patterned, multiple, and multiple blocks with full coating and patterns) were compared to bulk heating. The study highlighted the improvement in evaporation rate achieved using floating absorbers by 43% and 56% for single and multiple absorbers under one sun illumination compared to bulk heating. Also, a multiple absorber design yields a 10% higher evaporation rate than a single absorber. An extended analysis with and without black coating on multiple absorbers design indicates an improvement of 17% evaporation efficiency compared to bare multiple absorbers. In selecting a suitable pattern embedded on the single absorber, the stripe-type pattern resulted in a 21% improvement in evaporation rate than the bare absorber among the four patterns tested. The multiple absorbers with stripe patterns obtained an evaporation rate of 1.17 kg m−2h−1under one sun (1 kWm−2) irradiation. Further, the multiple absorbers with stripe-type patterns obtained an evaporation rate of 1.69 kg m−2h−1under 1.5 sun irradiation (1.5 kWm−2).