Raja TABOUBI
This article presents a comprehensive approach for the design, sizing, and evaluation of a 300 kWp photovoltaic installation integrated into a residential roof and connected to the STEG grid. Based on the objectives of the Tunisian Solar Plan, the STEG specifications, and the geographical constraints of Tunisia, the study combines theoretical analyses, advanced modeling, and simulation using PVSyst to ensure a system that is efficient, safe, and compliant with international standards. The detailed methodology covers: • the choice of solar modules (technology, power, temperature coefficients) and inverters (maximum efficiency, voltage and current ranges) • the definition of field-inverter architectures (centralized vs. string) and the calculation of series/parallel configurations • the sizing of cables and protective devices (fuses, surge arresters, differential devices) according to IEC 61215, IEC 61730, IEEE 1547 and IEC 61724 • the implementation of dual-diode simulation and maximum power point tracking (MPPT by incremental conductance) algorithms PVSyst simulations integrate local irradiation profiles, thermal conditions, and system losses to estimate the performance ratio (PR) and annual production level. The economic analysis details the overall cost, the LCOE (Levelized Cost of Energy), and the payback period, taking into account STEG subsidies, ANME grants, and international financing mechanisms. The results highlight: • A performance ratio greater than 80% in the chosen configuration • A competitive LCOE compared to STEG residential rates • A repayment period of less than 8 years • A significant reduction in CO₂ emissions over the lifetime of the project This study demonstrates the technical feasibility and economic viability of a 300 kWp PV plant in a Tunisian residential environment, while providing a reproducible framework for other projects of similar size.