Real-Time Monitoring and Performance Optimization of Rooftop Photovoltaic Systems Based on a Simplified Digital Twin Architecture

Abstract

Photovoltaic (PV) systems are increasingly being deployed on building rooftops as part of renewable energy strategies, yet their performance remains highly sensitive to local meteorological conditions and is often poorly correlated with manufacturer datasheet values or generic simulation assumptions. This paper proposes a simplified digital twin (SDT) for a rooftop-mounted 11 years old PV system equipped with Altius photovoltaic panels which integrates real-time operational monitoring and on-site meteorological measurements. Experimental current-voltage (I-V) and power-voltage (P-V) characteristic curves were obtained through direct testing with HT IV400 of the Altius panels and compared to the curves of a new PV panel in order to determine the degradation of the PV panels. A dedicated meteorological station, co-located with the PV installation, provides synchronized values of irradiance, ambient temperature, and PV panel temperature, enabling the digital twin to be continuously updated with real operating conditions rather than standard test conditions (STC) assumptions. The real-time monitoring system collects DC and AC parameters directly from the rooftop PV installation over a one-minute period, allowing the digital twin to compare the real output power with the theoretical one computed using the datasheet characteristics, solar irradiation and PV module temperature in order to provide notifications related to the health of the PV system, if the string is connected or if the inverter is connected to the grid.