Photovoltaic power optimization using sliding mode control with a two-axis tracking system

Optimal power tracking techniques are often employed to more effectively extract the power generated from photovoltaic (PV) modules. This paper examines the problem of adjusting PV module's position to maximize the incident irradiation, and hence, the power. It introduces a two-axis rotation control mechanism to track a PV module's maximum power based on the sun's azimuth and elevation angles. The control mechanism uses the sliding mode control method of self-optimization without depending on the astronomical data for the sun trajectory. The power generated depends heavily on the solar intensity (irradiance); however, total irradiance on any inclined surface is the sum of direct irradiance, isotropic sky diffuse irradiance, and ground reflection. The proposed controller architecture efficiently maintains the power around an optimum value, by orienting a PV module to the corresponding azimuth and elevation optimal angles.