This paper reviews the mechanisms, causes, and detection techniques of photovoltaic (PV) module failures and degradation. It highlights the importance of understanding these issues due to the increasing deployment of PV modules globally. The review covers various components of PV modules, including protective glass, encapsulant, solar cells, backsheet, and junction box, detailing their specific failure modes and root causes. It also discusses the hazardous consequences of failures, such as reduced efficiency, safety risks, and potential fires. The paper emphasizes the significance of electrical characterization techniques for early detection and prevention of failures. Additionally, it provides a classification of PV failures based on severity, location, and occurrence time, and explores the impact of environmental stress factors like temperature, humidity, and UV radiation on PV module degradation. The review concludes by proposing future research directions to develop more effective solutions and corrective actions for ensuring the reliable and safe operation of PV systems.This paper reviews the mechanisms, causes, and detection techniques of photovoltaic (PV) module failures and degradation. It highlights the importance of understanding these issues due to the increasing deployment of PV modules globally. The review covers various components of PV modules, including protective glass, encapsulant, solar cells, backsheet, and junction box, detailing their specific failure modes and root causes. It also discusses the hazardous consequences of failures, such as reduced efficiency, safety risks, and potential fires. The paper emphasizes the significance of electrical characterization techniques for early detection and prevention of failures. Additionally, it provides a classification of PV failures based on severity, location, and occurrence time, and explores the impact of environmental stress factors like temperature, humidity, and UV radiation on PV module degradation. The review concludes by proposing future research directions to develop more effective solutions and corrective actions for ensuring the reliable and safe operation of PV systems.