The aim of this paper is to find a simple model to predict the maximum power of a high concentrator photovoltaic (HCPV) module under real conditions from easily obtainable atmospheric parameters. The model is based on a simple easy to use equation. This equation is the function of direct normal irradiance and air temperature and has an additional correction based on air mass. In order to define this equation, two HCPV modules from different manufacturers were measured over a period of two years to provide a complete set of measurements, representing the behaviour of HCPV modules in different outdoor conditions. The proposed model shows an adequate match between actual and estimated data for the particular HCPV modules located in Southern Spain. (C) 2013 Elsevier Ltd. All rights reserved.