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. (C) 2015 Elsevier Ltd. All rights reserved.