Solar hybrid tracking system under complex weather conditions and control criterion

Solar tracking technology has been widely used in large power stations, photovoltaic agriculture, and green building industry. Among them, hybrid tracking can be expected to consider both photoelectric and solar trajectory tracking. However, it is still lacking in the accurate evaluation of different weather conditions, due to the excessively broad control criterion in the solar hybrid tracking using light intensity, and the vague conditions for the weather identification. In this research, a solar hybrid tracking system was designed under complex weather conditions. Moreover, a multi-threshold control criterion was proposed to divide the weather conditions. The tracking characteristics of the system were analyzed under different tracking strategies in the concentrated and non-concentrated environments, combined with the weather conditions. The control criterion was classified into irradiance fluctuation, high irradiance, low and extremely low irradiance weather. As such, the photoelectric and solar trajectory tracking automatically adjusted, or fixed the inclination angle, according to the external weather changes. Firstly, the prototype of a hybrid tracking system was developed for solar power generation. Specifically, the Raspberry Pi 4B controlled by Node-Red was used as the control core, and the signal was divided by the analog switch of CD4052. At the same time, the photoelectric tracking signal and the fixed inclination angle placement signal were outputted by Arduino, whereas, the tracking signal of the solar trajectory was outputted by STM32F407. Three-way parallel control was adopted to avoid interference with each other in the different control strategies. Secondly, a series of tracking tests were carried out to determine the foundation for the switching of the tracking system under concentrated and non-concentrated light conditions. The switching criteria were summarized for the hybrid tracking system since the tracking performance of the system varied depending on the weather and the tracking mode. The irradiance and power generation curves were also determined that the system received under various tracking strategies. A hybrid tracking scheme was developed to investigate the influence of weather on irradiance characteristics, in order to keep tracking the temperature change of battery panels. The irradiance and temperature curves demonstrated that the irradiance was the primary determinant of the variance in PV cell output, while the temperature remained constant. As a result, the hybrid tracking system can be expected to track the high irradiance for higher power production. Finally, the tracking prototype was tested to verify the impact of the criterion program on the hybrid tracking system. The test results showed that the average power generation of a no-concentrated hybrid tracking system on a sunny day was 0.03 and 0.16 W higher than that of photoelectric and solar trajectory tracking. Additionally, the average power generation of the concentrated hybrid tracking system on a sunny day was 0.81, which was 0.03 and 0.55 W higher than that of photoelectric and solar trajectory tracking. Anyway, the experiment verified the feasibility of the developed device. The new criterion can also provide a promising idea for hybrid tracking technology under complex weather.