Central inverters convert the DC voltage from "strings" of photovoltaic (PV) panels to AC voltage and are used in residential, commercial and utility scale systems with power levels of 1kW or higher. The maximum power point tracking (MPPT) for the PV panels is performed centrally at the DC-AC inverter stage.
Central Maximum Power Point Tracking System (C-MPPT)
In the central-MPPT systems, PV modules are connected in combinations of series and parallel configurations.
The PV modules connected in series are called “strings.” MPPT can be performed at the system level or at the string level. The output voltage of each string can be between 150V and 1000VDC. In order to generate the peak grid voltage, these systems need a boost step (converter or transformer), which is performed at the output of the string. Single-stage inverters (using full-bridge or neutral-point clamp topologies) achieve higher efficiency, less system cost, better efficiency and longer lifetime.