This paper mainly introduces the system of sun-tracking control in CPV (Concentrating Photovoltaic), includes new
structure design, process circuit and software design. This system includes five photoelectric sensors, five optical fibers,
one microcontroller, two-axis motion mechanism and motors etc. Here a center fiber is used to determine whether the
sun appears and get a reference illuminance, and other four fibers are symmetrically distributed around the center fiber.
The optical fibers lead sunlight energy into photoelectric sensors and their length can be adjusted according to actual
case. So that system is flexible and has good anti-jamming. The difference value of optical energy gained by each pair of
opposite optical fiber is important measure data processed by MCU. Through the calculate result by a MCU, the system
can gain the direction of the sun in real time. In addition, this paper presents processing circuit, software about control
process as well as error analyzes. The software also provides a scheme for suiting any weather. This new structure can
protect the photoelectric sensor in any case of the weather and environment, because the sensors are deeply put inside the
instrument and the light energy is passed by the fibers. More than that, through calculating the difference value of each
opposite pair of fiber, controlling the motors and increasing the accuracy of sun-tracking can be realized.