Currently, the production and the number of installations of photovoltaic (PV) modules have been increasing rapidly because of a feed-in tariff in Japan. Accordingly, the number of failures has also increased. Many failures are a result of the Hot-Spot phenomenon in which defective cell becomes hot when shadow occurs on the cell. On the other hand, if shadow occurs on a normal cell, generated power is decreased because of shadow. The correspondence is required rapidly because of occurring abnormity. However conventional PV system monitors generated power, detection of occurring shadow and the Hot-Spot detection are difficult by monitoring generated power. Previously, the authors performed operating analysis of the PV module with Hot-Spot. Moreover we proposed novel abnormal diagnostic method that detects occurring shadow and Hot-Spot with PV string based on the result of the analysis. This paper investigates the Hot-Spot detection system for a single-crystal photovoltaic module in real time using slope of I-V (Current-Voltage) characteristics, and confirms effectiveness of the system. Applying this system to PV system, the Hot-Spot can be easily detected in real time.

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