###### Abstract  
When a photovoltaic (PV) system is exposed to physical objects and cloud coverage and connected to bypass diodes, a partial shading condition (PSC) occurs, which causes a global maximum power point (GMPP) and numerous local maximum power points (LMPPs) on the power-voltage (P-V) curve. Unlike conventional MPPT techniques that search for multiple LMPPs on the P-V curve, it is possible to track GMP straightaway by designing a simple but robust MPPT technique that results in faster tracking speed and low power oscillations. Hence, in this study, an improved proportional-integral (PI) coordinated Maximum Power Point Tracking (MPPT) algorithm is designed to enhance the conversion efficiency of a PV system under PSC with fast-tracking speed and reduced power oscillations. Here, PI controllers are used to mitigating the steady-state errors of output voltage and current of PV system that later on passed through an incremental conductance (INC) algorithm to regulate the duty cycle of a dc-dc boost converter in order to ensure fast MPPT process. The PV system is integrated with the grid through an H-bridge inverter, which is controlled by a synchronous reference frame (SRF) controller. Tracking speed and steady-state oscillations of the proposed MPPT are evaluated in the MATLAB/Simulink environment and validated via a laboratory experimental setup using Agilent solar simulator and dSPACE (DS1104) controller. Results show that the proposed MPPT technique reduces the power fluctuations of PV array significantly and the tracking speed of the proposed method is 13% and 11% faster than the conventional INC and perturb and observe (P&O) methods respectively under PSCs. MPPT; PWM; partial shading condition; PV; grid-connected; incremental conductance and PI +
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cost-effective, renewable, and non-polluting [4]. Solar cells that made of Gallium Arsenide (GaAs) are widely used in space technologies and objects, which can be operated efficiently at any weather conditions and dynamic operating conditions [5]. The GaAs solar cells are integrated with modern iridium satellite constellation. These types of solar cells consist of high resistive materials against radiation effect and other external disturbances [6]. The grid-connected PV system combined with solar converters is designed to harness energy from the PV modules and delivers surplus energy to a power grid, which reduces household electricity bills, and meets electricity demands [7]. Recently, a substantial number of PV systems are integrated with the utility grid because of its increasing demands and reliable operations compared with other renewable sources [8]. The Power versus Voltage (P-V) and Current versus Voltage (I-V) characteristics curves of the modules are nonlinear, especially when a PV system is operated under dynamic weather conditions, variable loads, and inconsistent temperature [9]. Cloud cover, trees, buildings, and bypass diodes cause a partial shading condition (PSC) with numerous power peaks on the PV string [10]. The location of an operating point and maximum power points (MPPs) is dynamically changeable when the PSC condition occurs on the PV module. Hence, an online Maximum Power Point Tracking (MPPT) algorithm is required to harness the maximum energy from a PV panel by driving the operating point toward the nearest global MPP (GMPP) region [11]. The increased perturbation size of a converter duty cycle increases the tracking speed and power oscillations around the GMPP and vice versa. Because of this unforeseen relationship, a variable step perturbation of the duty cycle should be applied to achieve higher efficiency in PV MPPT design [12]. Conventional MPPT algorithms (see simulation codes in Appendix A) are mostly designed to track the GMPP under uniform environmental conditions where the P-V curve generates only one MPP [9].