Large-scale PV plants have the ability to make the curtailment of cost per watt of the normal power installed. This article describes a new technique for computing the optimal contour of large PV plants. Massive infiltration of renewable energy sources is increasing because of the awareness created on environmental issues and electric power deregulation. A PV system is a renewable energy source that establishes a future sustainability in power distribution. The technical specifications details are provided by solar irradiation and performance ratio. High accuracy of energy generation followed in computations in the proposed system. The high-accuracy feature is validated using experimental data of the 90MW PV plant in Cambodia. The results obtained show that the optimisation method can lead to a reduced cost of energy generated. This enables the maximisation of the benefit obtained on the operational life period of the PV module. The model’s accuracy depends on a hierarchical structure level model, model measurement accuracy, model identification, structure accuracy, measurement accuracy, simulator algorithms metrics, and the accuracy of the calibration parameter. The paper is built based on the physical ranking of the PV power model structure, making the system a high-fidelity model.