Novel deterioration diagnosis device for individual photovoltaic modules useable without disconnecting electric wiring in solar cell string

A novel deterioration diagnosis device for individual photovoltaic modules useable without disconnecting electric wiring in a solar cell string was proposed by improving the authors' previous deterioration diagnosis device for a single separated photovoltaic module. As with the previous device, this proposed device employed a xenon flash lighting system and a detector capacitor. An auxiliary diode network was newly installed as the additional improvement to enable connection of the previous device to the solar cell string and to realize the diagnosis of each photovoltaic module connected in the solar cell string. Before performing demonstration test experiments of the proposed device, preliminary assessment of its diagnostic capability was carried out through numerical simulations. The simulation results suggested the validity of the proposed device. Based on this positive evaluation, a prototype experimental apparatus of the proposed device was then assembled and the demonstration test experiments were carried out by using it. As a result, both the usability without disconnecting electric wiring in the solar cell string and sufficient deterioration diagnosis capability of the proposed deterioration diagnosis device for individual PV modules connected in a solar cell string were successfully confirmed.