International Journal of Electrical and Computer Engineering (IJECE) Vol. 12, No. 5, October 2022, pp. 4559~4570 ISSN: 2088-8708, DOI: 10.11591/ijece.v12i5.pp4559-4570  4559 Journal homepage: http://ijece.iaescore.com Tunicate swarm algorithm based maximum power point tracking for photovoltaic system under non-uniform irradiation Evi Nafiatus Sholikhah, Novie Ayub Windarko, Bambang Sumantri Department of Electrical Engineering, Politeknik Elektronika Negeri Surabaya, Surabaya, Indonesia Article Info ABSTRACT Article history: Received Jun 15, 2021 Revised Apr 20, 2022 Accepted May 15, 2022 A new maximum power point tracking (MPPT) technique based on the bio- inspired metaheuristic algorithm for photovoltaic system (PV system) is proposed, namely tunicate swarm algorithm-based MPPT (TSA-MPPT). The proposed algorithm is implemented on the PV system with five PV modules arranged in series and integrated with DC-DC buck converter. Then, the PV system is tested in a simulation using PowerSim (PSIM) software. TSA-MPPT is tested under varying irradiation conditions both uniform irradiation and non-uniform irradiation. Furthermore, to evaluate the performance, TSA-MPPT is compared with perturb & observe-based MPPT (P&O-MPPT) and particle swarm optimization-based MPPT (PSO-MPPT). The TSA-MPPT has an accuracy of 99% and has a reasonably practical capability compared to the MPPT technique, which already existed before. Keywords: DC-DC buck converter Maximum power point tracking Non-uniform irradiation Photovoltaic system Tunicate swarm algorithm This is an open access article under the CC BY-SA license. Corresponding Author: Evi Nafiatus Sholikhah Department of Electrical Engineering, Politeknik Elektronika Negeri Surabaya Raya ITS St., Surabaya City, East Java 60111, Indonesia Email: evinafiatus30@mail.com 1. INTRODUCTION The installation of photovoltaic (PV) modules arranged in series-parallel to form PV arrays for solar power generation has grown quite fast in recent years. The electrical energy produced by the PV array is very dependent on environmental conditions, such as solar irradiation and temperature [1]. One of the factors that affect solar irradiation is partial shading conditions. Partial shading is a condition where the PV array is partially covered by dust accumulation, building shadows, tree shadows, or clouds. It causes the PV array to receive non-uniform irradiation. In addition, some of the PV arrays covered in shadows will be energized by the current generated by the PV arrays that are not covered in shadows. So, the power generated by the PV array will decrease significantly compared to uniform irradiation conditions. This condition will also increase the PV module temperature, causing a hotspot on the PV module, so the degradation of the PV module will accelerate. To reduce the effect of partial shading is to install a bypass diode on each PV module. As a result of the installation of this bypass diode, the PV array characteristics have several power peaks, namely global maximum power point (GMPP) and local maximum power point (LMPP) [2]–[4]. One solution to increase the PV array output power efficiency is the maximum power point tracking (MPPT) technique to track the PV array maximum power. The MPPT technique consists of an algorithm implemented into a microcontroller system integrated with a power converter and sensors. The implemented algorithm is used to determine the duty cycle, which is then used to control the switching of the power converter. The MPPT technique has developed quite rapidly in recent years, with various algorithms classified into conventional algorithms and soft computing algorithm that can track maximum power points under uniform irradiation and non-uniform irradiation conditions [5]–[7].