Currently, the production and installation quantity of photovoltaic modules is has been increasing rapidly. Meanwhile, the failure cases are also increasing. Accordingly, many failures are results of the Hot-Spot phenomenon. This is a phenomenon in which the entire or part of the defective cell becomes hot when shadow occurs on the cell for a long period. In severe cases, the phenomenon causes breaking of the cell and a fire. While there are many Hot-Spot inspection methods, such as using infrared cameras, the inspection instruments of these methods are expensive, and these methods also require a lot of time and effort during the inspection. Previously, the authors proposed a Hot-Spot detection system included into PCS. In this paper, we proposed plug-in type Hot-Spot detection system, and report about effectiveness of the system.