Hybrid Renewable Energy Systems (HRES) combine multiple renewable energy sources to mitigate the intermittent issues associated with individual systems, like solar or wind, ensuring more stable and reliable energy output. HRES are crucial for electrifying remote areas not connected to the national grid. They provide energy independence and improve the quality of life for communities, as seen in the Solar Hybrid Station at RPS Kemar, Gerik, Perak [1] . Integrating solar photovoltaics with pumped-storage hydropower (PSH) is particularly effective.

Solar PV generates energy only when the sun shines, while PSH stores surplus solar energy as potential energy in water, which is released when solar power is unavailable. This integration, as seen in Figure 1 , not only optimizes energy utilization but also enhances grid stability while reducing CO₂ emission [3] - [5] .

The core concept of a solar-Pumped Storage Hybrid Energy System is to use solar PV to directly power loads or charge a battery. Excess solar energy is used to pump water into an elevated reservoir, storing the energy as potential energy. When solar energy is unavailable (e.g., at night or during cloudy periods), the stored water is released through turbines to generate electricity, ensuring a continuous power supply [6] [7] . This integration, as can be seen in Figure 2 , solves the intermittency of solar energy by providing backup power from the PSH system during low solar input, making it especially beneficial for off-grid areas [8] .

Arduino-based systems have become a popular choice for real-time monitoring and control in renewable energy applications, particularly in hybrid solar and pumped storage hydropower (PSH) systems. These systems automate essential processes such as water pumping and energy management, improving efficiency and reliability. For example, one study demonstrated the use of Arduino for automating solar-powered pumps, where it optimizes the pump’s operation based on solar generation and water flow conditions, ensuring efficient energy usage [9] . Another example integrates Arduino with micro-hydro systems for frequency control, stabilizing power output by dynamically adjusting system parameters [10] .

In hybrid systems, Arduino interfaces with various sensors such as current monitors and water level detectors, enabling real-time management of energy flow between components. The use of Wi-Fi modules like the ESP8266 allows for remote monitoring, making the system more adaptable for off-grid applications [9] . Furthermore, the integration of Arduino enables the use of Maximum Power Point Tracking (MPPT) algorithms to optimize solar energy conversion and manage the switching between solar and hydro power generation based on environmental conditions and load demands [10] .

Arduino’s ability to interface with multiple sensors and actuators, along with its low cost and ease of use, makes it an ideal choice for developing scalable, efficient hybrid renewable energy systems [11] - [14] . These systems can be deployed in off-grid areas to enhance energy access and sustainability, offering real-time control, data logging, and improved system performance by integration of an Arduino Uno.

In conclusion, combining solar PV with pumped-storage hydropower (PSH) in Hybrid Renewable Energy Systems (HRES) offers a reliable solution for off-grid energy generation, addressing solar intermittency [15] - [17] . Arduino-based systems enhance efficiency by automating control, real-time monitoring, and data logging. The flexibility and low cost of Arduino make it ideal for developing scalable, sustainable systems in remote areas, ensuring continuous energy supply [18] - [20] . Future improvements in system optimization and energy management will further strengthen the potential of these hybrid systems.

This project focuses on developing a small-scale hybrid system that integrates solar photovoltaic (PV) technology with pumped-storage hydropower (PSH). The primary goal is to design and implement a system that can autonomously switch between solar power and hydro generation, ensuring a continuous energy supply for off-grid applications. The methodology involves system design, hardware implementation, and performance testing to evaluate the feasibility and efficiency of the hybrid system.

The hybrid system design integrates solar panels, a hydro generator, a battery, and an Arduino Uno microcontroller for controlling and monitoring system operations. Key components of the system include:

This system design ensures that the transition between solar and hydro generation is smooth, minimizing system downtime and maintaining a reliable energy supply.

The system architecture is divided into four main phases as can be seen in Figure 3 .

The phases were explained as follows.

This architecture enables seamless operation of the hybrid system, with automated switching between solar and hydro generation based on the availability of solar power and the energy demand. The system is designed to be scalable and adaptable to various off-grid applications.

The hybrid system was tested through simulation using Proteus to evaluate the system’s performance and the capability of data logging under different conditions as illustrated in Figure 4 . The simulation was designed to replicate real-world conditions, including varying sunlight and load scenarios.

The Proteus simulation demonstrated the system’s ability to seamlessly switch between solar power and hydro generation. During periods of high sunlight, the solar panels charged the battery and powered the system, while the water pump was activated to store excess energy in the elevated reservoir. When solar generation decreased (e.g., during cloudy conditions or at night), the simulation showed that the hydro generator automatically took over, providing continuous power by releasing stored water to generate electricity.

Furthermore, the data logging functionality was successfully simulated in Proteus as can be seen in Figure 5 . Data from various sensors, such as voltage, current, water levels, and battery charge status, were continuously logged and displayed in real time. The system recorded all parameters onto an SD card, which was simulated to track the energy production from both the solar and hydro sources, and the system’s overall performance. The simulation confirmed that the hybrid system could reliably maintain energy supply, with the Arduino controlling the switching process and managing data logging without interruptions.

The simulation results showed that the hybrid system provided a stable and continuous power supply, effectively managing energy from both the solar and hydro sources. This confirms the viability of the system for real-world applications and demonstrates the importance of simulation in testing the system’s behavior and performance before physical implementation.

Data was systematically collected over multiple days and tabulated in Table 2 , Table 3 and Table 4 to assess the performance of the solar panels, water pump, and hydro generator within the hybrid energy system. This process included monitoring voltage, current, temperature, and power generation under various environmental conditions and can be divided into several performances as follows.