Copper indium gallium selenium (CIGS) photovoltaic (PV) devices exhibit unique reverse breakdown characteristics in terms of the dependence on temperature, light intensity, photon energy, and buffer layer material. In this work, the theoretical basis of potential reverse breakdown mechanisms are described and compared to available data. Quantitative analysis performed with semiconductor device simulation indicates that none of the conventional reverse breakdown mechanisms can account for the observations. Further work to better understand the reverse current-voltage characteristics of CIGS PV devices will provide insight to improve performance and reliability.