The incident angle is a critical factor impacting the performance of fixed photovoltaic (PV) modules. Off-normal incidence leads to significant changes in the current-voltage (I-V) characteristics and serious deterioration in the performance of fixed PV modules, resulting in difficulties in achieving optimal use of the available solar energy and retaining the maximum power output. To investigate this problem in depth, we develop a theoretical method based on the material properties and recombination mechanisms of the semiconductor, which can be used to directly evaluate the incident angle dependence of the energy harvesting performance and the maximum power point (MPP) estimation of PV modules composed of different materials from their I-V characteristic curves under irradiation. The proposed method is a simple approach with a low calculation burden. The performance of the proposed method is evaluated by examining the characteristics of the open-circuit voltage, short-circuit current, MPP, and the maximum output power of PV modules constructed of different semiconductor materials with respect to the various incident angles. The results are discussed in detail. The experimental results demonstrate that the proposed method could be used to optimize the performance of fixed PV modules and realize MPP control of PV systems during practical operation. Copyright (C) 2013 John Wiley & Sons, Ltd.