Reliability of DC-DC converters is important in photovoltaic (PV) applications like building integrated PV systems, where the module-level converter may be stressed significantly. Understanding and predicting the most life-limiting components with accurate degradation models in such systems enable the design for reliability. In this paper, a mission profile-based reliability analysis framework for PV DC-DC converters is proposed where the inputs and models of the framework can be adjusted according to the converter topology, the components and the failure mechanisms under investigation. The framework is demonstrated by comparing the influence of two yearly mission profiles on the solder joint degradation of a MOSFET in an interleaved boost converter. This is done by using an electro-thermal circuit simulation in PLECS and a finite element MOSFET model in COMSOL. This framework allows for exploring more accurate models or even simplifying parts with low sensitivity in order to obtain a thorough understanding of their accuracy and to determine the overall converter reliability.