The current state and the future potentials of renewable energy have increased widely globally to reduce the usage of other resources such as fossil fuel, which affect the environment. NEOM city in the Kingdom of Saudi Arabia (KSA) is a case where renewable energy will count for 100% of its energy consumption. Solar energy will play a prominent role in NEOM city. This project aims to present a design and simulation of a standalone photovoltaic (PV) system for a mosque located in NEOM city to meet the people's need for electricity. The system harvests solar energy and converts it into electrical energy to cover the electrical power needed for a typical mosque in NEOM. The design and simulation have been implemented using PVsyst software, powerful software for designing, simulating and generating PV systems reports. The designed standalone PV system could produce yearly electrical energy of 300 MWh. This study's significance relies on initiating research and development of building PV systems to harvest solar energy in NEOM city.