Approach for dimensioning stand-alone photovoltaic systems

In fact, these devices could be deployed into the system by decoupling energy production from consumption mainly by storing the extra produced energy from renewable energy sources during the day for eventual usage at night. However, for standalone systems, computing the optimum size of energy production systems and storage devices is required for continuous electricity supply. Morocco is focusing on renewable energies, especially solar, to reduce its external energy dependence, which is around 95%. The country's average daily global radiation is around 5kWh/m2, making it an ideal location for solar energy production. Batteries are among the most used storage devices in stand-alone photovoltaic systems due to their benefits, including fast response, modularity, and good energy efficiency. Modeling and sizing stand-alone PV systems have been widely studied in the past years to facilitate their installation and enhance their behavior. The sizing of each component of these systems requires a prior knowledge of many important parameters, including solar irradiation, ambient temperature, and consumption profile. Several models have been proposed for each component to evaluate their behavior under various conditions. A micro-grid system is composed of five main components: PV panels to generate electricity from solar radiation, batteries to store energy for nighttime and cloudy days, a regulator to control charging and discharging of the batteries, an AC/DC converter to convert alternating current from the electric grid to direct current, and the electric grid to supply electricity to the system when there is no production and the batteries are empty. The system was evaluated, and its performance was studied to figure out their behavior and the amount of electricity supplied from the electric grid. A sizing method was developed to make the system a standalone system, where the focus was on modeling the system and conducting simulations using similar experimental parameters. The models were then used for validating the proposed sizing method towards zero consumption from the electrical grid. The PV system was described, and the modeling together with the obtained results compared to the experimental results were introduced in Section 2. The size of each component of the stand-alone micro-grid system was computed, and simulation and experimental results were presented in Section 3. The architecture of the proposed micro-grid system was illustrated in Figure 1-a, which is mainly composed of a PV panel with a peak power of 265 Watts, a battery 24 Ah, and a ventilation system. The grid is connected to the system by an AC/DC converter that provides an output voltage equal to 12V. A platform composed of current, voltage sensors, and a relay was deployed to measure the current and voltage in each branch of the system. The relay is controlled by the Arduino board to switch between the PV-Battery system and the electric grid when the battery's state of charge reaches a given threshold. The micro-grid system was modeled and simulated under MATLAB/Simulink using similar experimental conditions. The models of PV panel, regulator, battery, AC/DC converter, and the electric grid were developed. The models of the PV panel and the regulator were described in more details in a previous work. Concerning the model of the battery, the Tremblay model was used to estimate the behavior of the battery, and the battery voltage was used as a parameter to estimate the state of charge according to the method presented in [9, 19]. The simulation and experimental results of the deployed micro-grid system were presented in Figure 3, showing the behavior of the system and the switching operations between the PV-battery system and the electric grid.