Amonix concentrating photovoltaic (CPV) solar power plants currently demonstrate AC efficiency of over 25% in the field. A model has been developed that predicts system performance based on the spectral response of the III–V multijunction cell corrected for environmental and atmospheric conditions. Historical meteorological data is used to predict future performance at target locations. With the cleaning schedule as the only adjustable variable, energy production has been within 2% of prediction after 9 months of operation. The model is used to improve performance, which is expected to increase by 10% in 2010. These improvements, combined with cost reductions in the MegaModule® design, put the Amonix CPV systems on track to achieve a levelized cost of electricity below US $100/MW-hr by 2012. Copyright © 2010 John Wiley & Sons, Ltd.