Solar fuels are chemical fuels produced using solar energy and include mainly formic acid, formate, hydrogen, and methanol. These solar fuels can be used as energy carriers. They can all be produced in places where solar energy resources are abundant, and then transported to places where energy is scarce. Therefore, they can alleviate energy shortages and reduce environmental pollution. Compared to other solar fuels, hydrogen has many interesting properties, making it the most studied and promising solar fuel.