Performance evaluation of a PVT/ORC (photovoltaic thermal/organic Rankine cycle) system with optimization of the ORC and evaluation of several PV (photovoltaic) materials

This paper presents a study of a combined PV (photovoltaic) and thermal system that utilizes waste heat at a high temperature to drive an ORC (organic Rankine cycle). Several configurations of the ORC are evaluated for performance with the use of twenty-seven working fluids, with the goal of identifying a combination that both provides the highest operating efficiency and meets design criteria for expanders. A design utilizing an internal heat exchanger and a closed feed fluid heater is found to have the highest performance when operated using alkanes. An analysis based on volumetric flow rate and volume ratio showed n-Butane to be the optimal choice for the proposed application. The optimized ORC is then examined in combination with several PV materials for improvements in efficiency.