A Low-Cost P&O based Maximum Power Point Tracking, Combined with Two-Degree Sun Tracker

Abstract

The output power of photovoltaic (PV) arrays varies with load, weather conditions, atmospheric temperature, and solar radiation. The maximum power of PV arrays can be achieved using maximum power point tracking (MPPT) strategies.  The perturbation and observation (P&O) technique is one of the simplest strategies which moves the operating point toward the maximum power point. On the other hand, it has been demonstrated that use of the sun trackers schemes in conjunction with MPPT control strategies gains the highest efficiency in photovoltaic systems. Most of sun trackers are single axis (azimuth) or axes (azimuth and elevation) systems, which both need geographical information of PV power plants. This paper conjugates the simple P&O MPPT technique with sun tracker based on light sensors. The proposed sun tracker is composed by a two-degree mechanical mainframe that supports the PV and allows moving in two axes. Therefore, there is no need to azimuth and elevation angles. A 25 Watt prototype PV system has been assembled in this work. The control system including the controller of buck/boost converter of MPPT systems as well as control of servo motors of two-axes have been implemented via an AVR microcontroller. Proposed system is tested in three cases; without MPPT, with MPPT and without sun tracking, and with both MPPT and sun tracking. Experimental results show that the proposed system ensures that the photovoltaic system delivers maximum power at all conditions.