Maximum power point tracking for building integrated photovoltaic ventilation systems

The objective of this project was to design a device to optimize the interface of a building integrated photovoltaic (BIPV) array with ventilation fans. The developed device tracks the maximum power point of the BIPV array and limits the output voltage to the level required by the fans. The purpose of maximum power point tracking (MPPT) is to automatically match the current and voltage characteristics of the load to the BIPV array´s maximum power point at any given illumination. To accomplish this a unique switch mode buck converter was used. The available power from the PV array is a total of approximately 2.5 kW. The two PV sub-arrays supply a voltage up to 220 VDC each and have a maximum power point voltage of 169 VDC. The load consists of two sets of six 133 W, 90 VDC ventilation fans. The device also has a soft-start circuit on board to start the motors slowly to avoid excessive current requirements from the array. This unit achieves efficiencies above 93%