NOVELTY - The systems (1, 1a, 1b) have multiple series module units in which multiple photovoltaic modules (M1-M3) are connected in a series manner. Multiple photovoltaic elements are provided on a module implementation unit (Mj) in the photovoltaic modules. The series module units are connected to each other in a parallel manner, and the photovoltaic modules are arranged in a same series stage and connected to each other in a parallel manner. Power conversion units (10) are connected to the photovoltaic modules, and perform direct current (DC)-DC conversion on output of the photovoltaic modules.    USE - Photovoltaic systems.    ADVANTAGE - The photovoltaic modules are connected in series in the series module units, arranged in the same series stage in the series module units and connected to each other in a parallel manner, thus suppressing the current pathway in the series module units even if a shaded area appears on the series module units, improving power generation efficiency and a power generation area ratio over the irradiated area ratio of the photovoltaic modules. The series module units are configured by the photovoltaic modules and arranged in a double-back pattern in order to two-dimensionally arrange the series module units in a dense manner, thus reliably distributing the photovoltaic modules according to the arrangement of the series module units, and improving resistance to shaded areas. The output voltage of the photovoltaic modules is boosted, so that the output current relatively decreased, thus suppressing the occurrence of ohmic loss caused by current in current pathways in a reliable and effective manner, and improving the power extraction efficiency. The power conversion units have a boosting factor that is fixed at one value, thus avoiding adjustment of the control signal for controlling the boosting factor of the power conversion units, and hence simplifying the control signal generation unit so as to reduce the installation cost of the power conversion units. The output of the photovoltaic modules arranged in the same series stage is input in a parallel manner, thus suppressing the number of power conversion units needed by the systems so as to reduce the number of parts and simplify the connection configuration, thus suppressing installation cost and maintenance cost of the systems and improving reliability of the systems.    DESCRIPTION OF DRAWING(S) - The drawing shows a block diagram of an arrangement of power conversion units connected to photovoltaic modules in a photovoltaic system.    Module implementation unit (Mj)    Photovoltaic modules (M1-M3)    Parallel wiring (Wpc)    Systems (1, 1a, 1b)    Power conversion units (10)