This paper presents an alternative way to transmit concentrated solar energy which may be applied in the hydrogen production by photoelectrolysis. It is possible to obtain high efficiency in the photoelectrochemical conversion systems with a simple structural design. The basic idea is to place an optical fiber in a paraboloidal mirror receptor plane. The concentrated solar energy is transmitted for a few meters by total internal reflection. The appropriate conditions existing between a paraboloidal mirror (reflective surface, Ag or Al) and an optical fiber (low doping, commercial type) is studied. The theoretical efficiency of the conversion system is obtained and analyzed.