A proposal of a procedure to estimate a standard line for contactless estimation of a solar cell voltage in a module using modulated light

It is important to measure the operating voltage of a cell sealed in a photovoltaic module as well as well-known faults such as abnormal hot spots observed by thermography or a dark part in electro-luminescence distribution on the module for detecting a fault module. This paper proposes a method that radiating modulated light toward a cell and extracting the synchronized signal from the module output by phase detector can estimate the operating voltage quantitatively by using a standard line predicted by shading the module partially.