The research article indicates the importance of carrying out measures for the diagnosis and maintenance of good-order standing shunt diodes as part of the solar panel. The study was carried out using the theoretical analytical analysis of information data on shunt diodes and their diagnostics. Defects considered solar panels due to defective shunt diodes. Used computer modeling in the PVSYST program, simulation of failures of shunt diodes on solar YL-250P-29b panels and their diagnostics by methods of short-circuit current analysis at partial shading and open circuit voltage parameter under normal conditions. It has been established that the methods of thermal imaging diagnostics (including using a drone) and visual inspection are not accurate tools. cops searching for faulty shunt diodes. For small solar power plants (as well as for diagnostic sticks of shunt diodes of solar panels from spare parts, tools, and fixtures on large solar power plants), short-circuit current analysis methods are applicable in partial shading and open circuit voltage parameter under normal conditions. For a complete diagnosis of shunt faults diodes at large solar power plants, the method of thermal imaging diagnostics using an external source.