Integrated long-term planning of conventional and renewable energy sources in Iran's off-grid networks

In this study, a combined power supply system consisting of renewable solar and wind energies with backup and storage equipment including a diesel generator and a Battery Energy Storage System (BESS) with Demand Response (DR) was integrated and optimized, and optimally enhanced the reliability of the sustainable supply of the load demand. This study aimed at investigating the optimization and evaluation of the cost and advantage of combined systems for off-grid power supply in four regions with different climatic conditions in Iran, including Zahedan, Kerman, Birjand, and Hamedan. The simulation results showed that for Zahedan, the cost per kilowatt-hour (kWh) of electricity with one day of autonomy and a maximum LPSP of 5% is $ 0.312 per kWh in the first year. By optimizing and altering LPSP and the optimal number of days of autonomy under various operating conditions, the capacity of the batteries was decreased from 3870 kWh (38%) to 1860 kWh (22%), which is almost half of the previous value. Furthermore, the cost per kWh of electricity in the first year decreased from $0.312 to $0.256. According to the results, such a hybrid system is cheaper than installing each of the solar, wind, or diesel generators separately. The conditions of the other three regions were then examined and analyzed and the results showed a direct correlation between the cost of electricity and the climatic conditions of each region. However, in general, considering the Levelized Cost of Energy (LCOE) with a RE hybrid energy system for many areas away from the grid in Iran and due to climatic conditions and the trend of reducing the final cost, the utilization of renewable energy sources is economically competitive with the main grid and technically feasible. It also can meaningfully diminish environmental pollutants in line with the objectives of the Paris Agreement.