This book analyzes the thermal characteristics of power electronic devices (PEDs) with a focus on those used in wind and solar energy systems. The authors focus on the devices used in such applications, for example boost converters and inverters under different operating conditions. The book explains in detail finite element modeling techniques, setting up measuring systems, data analysis, and PEDs’ lifetime calculations. It is appropriate reading for graduate students and researchers who focus on the design and reliability of power electronic devices.