Air filled asymmetric compound parabolic photovoltaic concentrators (ACPPVC) have been studied using a comprehensive validated unified model for optics and heat transfer in line-axis solar energy systems. The heat transfer that occurs within the cavity of a single concentrator, multiple concentrators, the space between adjacent concentrators and in an air duct behind the photovoltaics was simulated and is presented. For a range of insolation intensities incident at the aperture cover the maximum PV cell operating temperatures are determined. From the simulations undertaken the effects on solar cell surface temperatures resulting from air flow in the air filled space at the front of the system and in the air duct to the rear of the solar cells are clearly evident. (c) 2006 Elsevier Ltd. All rights reserved.