There are two main reasons for inspecting solar energy systems: safety and performance monitoring. Solar energy systems achieve their top performance in full sunshine. Testo thermal imagers can be used to monitor photovoltaic systems of all sizes in a way that is wide-ranging, contact-free and exceptionally efficient. Malfunctions are detected, the proper functioning of all components is ensured and the greatest possible efficiency is thus achieved. Additional reliability is also achieved through the ability to enter the key measurement parameter of solar radiation intensity: the value entered is stored with the thermal image and is then available for the image analysis.