Monitoring the performance of concentrating photovoltaic technologies under actual operating conditions is crucial for the prediction of energy yield. This requires an in-depth understanding of the behaviour of such systems through extensive outdoor characterisation and modelling. Detailed information on the outdoor performance of concentrating photovoltaic technology, taking into account the parameters that influence it, is therefore necessary for the evolution of the technology. In this work, a concentrating photovoltaic monomodule was characterised in a high desert climate (in Albuquerque, New Mexico). Due to the complexity of the outdoor performance evaluation of this technology, three relatively clear-sky days that exhibited different atmospheric conditions were selected in order to reduce the noise on the measured parameters and therefore provide a better understanding of its behaviour. One-minute resolution data were accumulated in order to assess the behaviour of the monomodule under real operating conditions. Initially, the monomodule is electrically characterised based on spectral changes. Different spectral indices are evaluated to enable a direct comparison amongst them. The diurnal electrical characteristics and temperature of the monomodule as a function of spectral, irradiance and ambient conditions is then analysed. The results of the three selected days show a maximum operating efficiency of 23.2% while maximum temperatures of 70.3 degrees C and 67.6 degrees C are observed on the diode and heat sink respectively. The importance of considering the influence of the atmospheric parameters on the performance of concentrating photovoltaics is also highlighted. In particular, spectral gains of up to 5% are exhibited due to lower aerosol content and higher precipitable water combined.