A Survey of Maximum PPT techniques of PV Systems Ali Nasr Allah Ali 1 , Mohamed H. Saied 2 , M. Z. Mostafa 3 , T. M. Abdel- Moneim 3 1 MSc. candidate, 2 PhD, GM, Electrical Engineering Dept., Abu Qir Fertilizers & Chemical Industries Co., 3 Full-Prof., Electrical Engineering Dept., Faculty of Engineering, Alexandria University, Alexandria, EGYPT. Ali.NasrAllah84@gmail.com, Mohammed.Saied@gmail.com Abstract—This paper introduces a survey of different maximum peak power tracking (MPPT) techniques used in the implementation of photovoltaic power systems. It will discuss different 30 techniques used in tracking maximum power in photovoltaic arrays. This paper can be considered as a completion, updating, and declaration of the good efforts made in [3], that discussed 19 MPPT techniques in PV systems, while summarizes additional 11 MPPT methods. Index Terms - Photovoltaic power generation, Maximum Power Point Tracking techniques, PV array. I. INTRODUCTION Tracking of the maximum power point (MPP) of a photovoltaic (PV) array is usually an essential part of PV systems. In general, PV generation systems have two major problems; the conversion efficiency of electric power generation is low (in general less than 17%, especially under low irradiation conditions), and the amount of electric power generated by solar arrays changes continuously with weather conditions. Moreover, the solar cell (current – voltage) characteristic is nonlinear and varies with irradiation and temperature. There is a unique point on the I-V or (power – voltage) curve of the solar array called MPP, at which the entire PV system (array, converter, etc…) operates with maximum efficiency and produces its maximum output power. The location of the MPP is not known, but can be located, either through calculation models, or by search algorithms. Therefore MPPT techniques are needed to maintain the PV array’s operating point at its MPP [1]. II. PROBLEM OVERVIEW As the solar radiation varies throughout the day, the power output also varies. The principle of maximum power tracking can be explained with the help of Fig. 1, where the line having slope I/R o represents a constant load R o . If this load is connected directly across PV cell, it will operate a power P a differs from the maximum P b , in spite of the fact that maximum power is available from the array. Thus, a power conditioner or DC-DC converter is introduced between the solar PV module and the load. This converter adapts the load to the array so that load characteristics are transformed along locus of maximum points and maximum power is transformed from the array. The duty cycle, D, of this converter is changed till the peak power point is obtained [2]. III. MPPT TECHNIQUES A 30 maximum peak power tracking methods for PV system will be introduced in the following survey. Fig. 1. Intersection between the load line and the power – voltage and current – voltage curve [2]. 1. Hill Climbing/P&O (perturb & observe) method Hill climbing involves a perturbation in the duty ratio of the power converter; P&O involves a perturbation in the operating voltage of the PV array. In the case of a PV array connected to a power converter, perturbing the duty ratio of power converter perturbs the PV array current, and consequently perturbs the PV array voltage; hill climbing and P&O methods are two different ways to perform the same fundamental method. It can be seen From PV power C/C s curve; Fig. 2, that the increment, or decrement of the voltage increases, or decreases the power when the operating point is on the left of the MPP, and decreases, or increases the power when being on the right of the MPP. The process is repeated periodically until the MPP is reached. The system then oscillates around the MPP. This oscillation can be minimized by reducing the perturbation step size. However, a smaller perturbation size slows down the MPPT. A solution to this conflicting situation is to have a variable perturbation size that gets smaller towards the MPP. A two-stage algorithm is proposed that offers faster tracking in the first stage. Hill climbing and P&O methods can fail under rapidly changing atmospheric conditions as illustrated in Fig. 3 starting from an operating point A, i.e. P 1 curve is utilized, if atmospheric conditions stay approximately constant, a perturbation ∆V in the PV voltage V will bring the operating point to point B and consequently the perturbation will be reversed due to a decrease in power.