Distributed PV systems are mostly rooftop plants integrated with buildings. If the quality of the plant is defective, it may not only damage the internal equipment of the plant but may even endanger the personal safety of people at and around the plant. Second, the electricity generated by a distributed PV plant is mostly consumed by the factory itself; if the plant quality is defective, it may damage the electrical equipment in use. Third, a distributed PV plant earns economic benefits from its generation output; if the plant quality is defective, it will affect the generation of the whole plant and thus reduce the overall revenue.