An MPPT Charge Controller for Solar PV Installations Using the Incremental Conductance Method

Small standalone photovoltaic systems of a few kilowatts rating consist of a solar array connected to batteries and parallel loads with a power electronic interface consisting of a DC-DC converter. The DC-DC converter aids in MPPT (Maximum Power Point Tracking) of the nonlinear solar array and supplies power to the load and charges the battery and is known as a “charge controller”. The solar array must be sized so that on normal irradiance, enough power is generated to charge the battery and supply the parallel load. If the DC-DC converter is a buck converter, the open-circuit voltage of the array must be more than the battery voltage. In case the converter is a boost converter, the combined battery voltage must be more than the open-circuit voltage of the solar array. If a buck-boost converter is used the polarity of the battery needs to be taken care of. If enough solar power is not being generated, the battery supplies power to the load. If the battery is completely discharged and insufficient solar power is being generated, the parallel load is disconnected from the battery, and output is zero. Operation resumes when sufficient power is being generated by the solar array. This paper is about a charge controller design, with MPPT based on the incremental conductance method. Operation is analyzed with a Buck converter.