Photovoltaic (PV) technology is in the forefront of renewable energy and gained a lot of attention as a very promising green technology towards direct solar energy conversion to electricity. So, enhancing the PV solar cell performance is an important target for improving PV system performance. In this paper, a recent algorithm called Arithmetic Optimization Algorithm (AOA) is proposed to find the optimal PV model parameters to build a Simulink model for an actual case study of the New and Renewable Energy Authority (NREA) 42 kW PV system. The results of the proposed AOA are compared with that obtained by means of particle swarm optimizer (PSO). Also, performance analysis is introduced for the practical measurements from the grid-connected PV system. Energy is measured for the installed PV system at the NREA in Cairo and the proposed system is simulated during daily weather conditions to test its operational performance based on simulation results. The system is installed to produce 2.17 MWh/year of energy production. Based on the optimal parameters for the study module using the proposed AOA, the detailed Simulink model of small-scale 42 kW PV system is accurately designed and connected to the utility grid. Furthermore, the output energy of the investigated system, with the aid of the proposed AOA, is efficiently estimated compared with the actual energy generated of case study.