Abstract: This paper focuses on AT89C51 single-chip microcomputer to realize the construction of automatic light harvesting system for solar panels.By adjusting the angle of the light receiving surface of the solar panel and the ray of the sun to evaluate the power generation efficiency.The collected optical signal is transformed into a voltage signal by the photoelectric sensor.The analog voltage signal transformed by the photoelectric sensor is transformed by the analog-to-digital conversion circuit module.After the voltage sampling process, the analog voltage signal is transformed into a digital voltage signal, and then the processed signal is transmitted to the single-chip microcomputer, which control the motor by the drive of the single-chip microcomputer and completes the task of automatic light harvesting of solar panels.