Research Of A Double-Axis Solar Automatic Tracking System

The solar automatic tracking system is an indispensable and important component in the field of developing and using solar energy. At present, photoelectric conversion rate of solar cell is very low, about 24% in lab, and about 15% in industrialization. Theory and analysis show that:at the same condition, the enery receiving rate of a tracked system is 37.7% higher than the non-tracking system in the solar power system. Therefore, in order to improve utilization rate of solar energy, a double-axis solar automatic tracking system which uses an AVR microcontroller as control core is researched and designed in this paper.On the basis of researching and analysing the principle of various international and domestic solar tracking devices, the double-axis solar automatic tracking system combines photoelectric detection tracking and solar altitude-azimuth tracking. Day and night are judged via reading GPS time information. Tracking modes are selected according to the weather condition. When it is sunny, the system adopts photoelectric detection tracking mode; When it is cloudy, the system is in temporarily wait state and not tracking blindly; At the moment of cloudy transforming into sunny, system selects solar altitude-azimuth tracking mode and adjusts in place then enters photoelectric detection tracking mode. The AVR microcontroller calculates and outputs stepping pulse to control the rotation of the stepping motor, and to realize automatic tracking the orbit of the solar. The solar energy cell which combines with the solar automatic tracking device can always point at the sun. When meeting the destructive windy day, the system detects the weather via wind speed-direction detection sensor to drive solar panel to twirl to the best dip angle, and then stepping motors stop runing. In order to manage the system better, solar cell's parameters are collected by acquisition modules and data are detected by sensors. These parameters and data are sent to PC via wireless communication. Based on the ICC AVR software development environment, we complete software design of the system. Software includes system main program module, photoelectric detection tracking module, solar altitude-azimuth calculation module, wireless communication module and other relevant function module.This system's hardware selection and configuration:The core control chip selects AVR ATmega64L, and design ATmega64L's peripheral hardware circuit, and make a detailed introduction for each parts'principle. Two pulse distributions PMM8713 and a power amplifier ULN2803 are choosed and connected to drive two stepping motors. A Nanotron's NA1TR8 based on IEEE 802.15.4a is selected to realize wireless communication. The wireless transceiver module contains NA1TR8, CDDL 1804,150Ω:50ΩBalun, BPF. A GS-15B provides GPS data. Wind speed--direction detection chooses wi29612 digital wind speed-direction detection sensor. During the design process, a detailed explanation is made for each module's function, hardware structure and circuit principle.Through the joint hardware and software debugging, double-axis solar automatic tracking system design is practical and feasible in this paper. This system has high tracking accuracy, reliable running, strong anti-jamming capability and strong practicability.