The power balance is considered a key requirement for designing a reliable power system that depends on renewable energy sources. To keep the stability of the electrical system and mitigate the power imbalances, an additional generating capacity called the operating reserve should be scheduled to meet the real-time demand. This paper deals with the feasibility of integrating several renewable energies with different nature, considering the operating reserve resulting from the integrating process. The operating reserve increases the efficiency and reliability of the hybrid renewable energy system. Three renewable energy sources are used to feed a residential building near the shore with electricity. Wind, wave and solar energies are used in this study because of the variability in the factors affecting the energy production process. This variability makes the power system more reliable due to the availability of energy at any time because of the different nature of energy production from the three proposed sources. A microcontroller is designed to combine the three sources together with the possibility of determining the operating reserve for each of the three sources. This controller based on the Buck-Boost converter technology. It reduces the fluctuations in the output voltage of each source and integrates them together. It operates through 4 scenarios depending on surrounding weather conditions. The controller shows high efficiency reached about 99.5% in adjusting the voltage to be connected to the battery bank or the inverter to feed AC loads. It takes only 0.18 s to reach the desired voltage. In addition to the high accuracy in determining the operating reserve resulting from feeding a residential building for 10 continuous hours during the winter.