Optimizing incident energy at the surfaces of solar modules is one of the most important parts of energy extraction. The goal of the solar-energy maximization problem is to maximize the amount of solar energy that strikes the flat surfaces of conventional flat solar-PV modules. The amount of solar energy that strikes the surface of photovoltaic (PV) panels is determined by the tilt angle of the panels. The position of the sun, latitude, and regional topography all affect the optimal tilt angle. This article discusses the optimal fixed-tilt solar-PV system angles for the Saudi Arabian city of Najran (18.00o N, 45.40o E). In addition to using meteorological equipment at the engineering college of Najran University in Saudi Arabia, LSI also gathered data on the city of Najran's horizontal solar radiation from "Climate.OneBuilding.Org." After evaluating the monthly, seasonal, and annual fixed-tilt choices, the optimum solution was selected. Najran's ideal annual tilt was determined to be 20.97 degrees. The annual ideal angle value was rather close to the latitude of the individual place. The range of 20.04 to 26.01 MJ/m²-day was discovered to be the average solar radiation at the annual optimal tilt. Based on monthly, seasonal, and annual ideal tilts, average annual solar radiation gains were projected to be 9.56%, 8.08%, and 3.32% higher than those of solar-PV modules put horizontally. In comparison to the optimal monthly tilt, the surface at seasonal and annual optimal tilts was predicted to lose 1.36% and 5.70% of its energy, respectively.