Proposed Solution to Infinite Loop Issues in the Digital Twin of a PV Array Based on the Single-Diode Model A Case Study

The growing demand for sustainable and clean energy has underscored the importance of photovoltaic (PV) power systems as essential to modern energy infrastructures. To optimize the efficiency of these systems, the integration of advanced technologies, such as digital twins (DTs), has become increasingly essential. In industrial PV applications, the deployment of DTs must satisfy several requirements, including preserving the existing system architecture, minimizing installation costs, and reducing commissioning time. This paper presents a photovoltaic (PV) monitoring system incorporating an industrial programmable logic controller (PLC) architecture. A digital replica of the PV array is implemented on the PLC based on the single-diode model (SDM). During this implementation, a challenge was identified regarding fluctuations in the current-voltage (I-V) characteristics caused by the simultaneous use of the model’s output as an input variable. The SDM was modified by integrating a lag function to overcome this issue. The proposed digital twin model was validated using real-world operational data. The results demonstrate that the coefficient of performance index ($\mathrm{R}^{2}$) between the digital twin and the measured I-V characteristics exceeds 0.9833. The modified model mitigates oscillations in the simulated I-V outputs.