The National Institute of AIST in Japan has developed a communication technology that uses the direct current (DC) power line of a solar panel as a communication line. The technology helps monitor the power generation in each solar panel, which is useful for the maintenance of the panel and the prompt detection of malfunctions. The monitoring unit of the developed communication system is small and can be placed in the terminal box of a solar panel. The system does not require additional wiring work because the existing DC power lines from the solar panels are used for communication.A high-efficiency power converter circuit has also been developed for distributed maximum power point tracking (Maximum Power Point Tracking, MPPT). The circuit enables extraction of the maximum power from each solar panel.