Several research works have investigated the direct supply of renewable electricity to electrolysis, particularly from photovoltaic (PV) and wind generator (WG) systems. Hydrogen (H₂) production based on solar energy is considered to be the newest solution for sustainable energy. Different technologies based on solar energy which allow hydrogen production are presented to study their benefits and inconveniences. The technology of water decomposition based on renewable energy sources, to produce hydrogen, can be achieved by different processes (photochemical systems; photocatalysis systems, photo-electrolysis systems, bio-photolysis systems, thermolysis systems, thermochemical cycles, steam electrolysis, hybrid processes, and concentrated solar energy systems). A comparison of the different methods for hydrogen production based on PV and WG systems was given in this study. A comparative study of different types of electrolyzers was also presented and discussed. Finally, an economic assessment of green hydrogen production is given. The hydrogen production cost depends on several factors, such as renewable energy sources, electrolysis type, weather conditions, installation cost, and the productivity of hydrogen per day. PV/H₂ and wind/H₂ systems are both suitable in remote and arid areas. Minimum maintenance is required, and a power cycle is not needed to produce electricity. The concentrated CSP/H₂ system needs a power cycle. The hydrogen production cost is higher if using wind/H₂ rather than PV/H₂. The green energy sources are useful for multiple applications, such as hydrogen production, cooling systems, heating, and water desalination.