In this investigation we selected four different Cu(In,Ga)Se2-based solar cells produced using different methods and with efficiencies ranging from less than 5% for the low-cost types to 20% for the highest efficiency process. These devices were intensively characterized using the optoelectronic methods of temperature-dependent current-voltage characteristics, capacitance-voltage measurements, and bias-dependent external quantum efficiency. By combining these methods it is possible to study the dominant recombination mechanisms in the devices and relate them to composition and morphology effects known through other characterization series. It was found that the highest efficiency cell has the least indication of interface recombination or tunneling effects; the temperature-dependent behavior is best described by recombination in the space-charge region. In contrast, the low-cost devices reveal high diode factors and a temperature dependence well described by tunneling-enhanced recombination at the interface. The consequences for the device behavior and recommendations for improvement will be presented. (C) 2012 Elsevier B.V. All rights reserved.