The concept of distribution flexible network PV system

In stand-alone photovoltaic (PV) systems, when the battery is fully charged, the excess generated power is wasted. To solve the problems of wasted excess power, a distributed flexible network photovoltaic (DFNPV) system is studied. It incorporates many PV subsystems each consisting of PV panel, DC/DC converter, and load, and are connected to each other with shared batteries. The excess generated power of the subsystem is transferred between PV subsystems to compensate the lack of power in other subsystems.The control method of transferring power is based on simple voltage control of the subsystems. The output voltage in a given subsystem decreases if a transient excessive load is larger than the generated power; as a result excess power is transferred from another subsystem that has sufficient power and higher voltage output. In this study, this proposed operation method is demonstrated by simulation of power transfer between two subsystems and among four subsystems. Furthermore, to estimate the size of the DFNPV system within an acceptable voltage drop, the relationships between cable length, power loss, and cable types are discussed.