Solar-tracking Fiber Light Guide Indoor Lighting System

With the booming development of the sunlight indoor lighting technology, researchers have been focusing on the issues of how to reduce the cost and improve the coupling efficiency of the solar energy. The indoor lighting technology of fiber light guide especially has a much more development potential among various solar lighting technologies. One reason for this is that it can avoid the problems of poor efficiency, high cost and pollution of solar batteries in optical-electrical conversion technology. In addition, it can transmit the clean and healthy sunlight into room directly, which can greatly reduce the lighting energy consumption and make people enjoy the pure natural sunshine indoor. The indoor lighting technology of fiber light guide has profound significance to our life.This paper designs an experimental solar-tracking fiber light guide indoor lighting system and makes a detailed analysis of solar tracker, solar condenser, light transmitting system and the reduction of indoor light. The real-time tracking through the high-precision solar tracker avails the solar condenser of the real-time reception of the direct sunlight so as to get the high-energy light intensity. Then, the focused sunlight is transmitted through the light transmitting system into the distal indoor after having filtered out the harmful rays.The solar tracker designed in this paper adopts the way of the GPS-based sun trajectory movement tracking and the way of closed-loop tracking calibration of four-quadrant silicon photocell photoelectric tracking. The way of solar-tracking lies in utilizing the program in single chips to calculate the sun movement trajectory, four-quadrant silicon photocells to conduct position calibration and stepper motor to drive the gear set for the achievement of high-precision control.In the part about the condenser, an introduction is mainly focused on the commonly-used convex lens, Fresnel lens and the Cassegrain condenser. By comparing their performances, advantages and disadvantages, the Fresnel lens is selected as the condenser in the system concerned.At present, optical fiber and light pipe are mainly used in the light transmitting system of solar light guide. Accordingly, the light guide principles of optical fiber and light pipe are introduced, their performances are analyzed and finally the14-core plastic optical fiber cable is chosen as the light transmitting system in this paper.After the sunlight is focused through the Fresnel lens and then transmitted into the indoor room though the light guide of optical fiber, the light out of the light side of fiber optic cable is very bright and the emergence angle is small, failing to achieve the effect of the sunlight exposure, and therefore there is a need for sunlight reduction. For the present, the main ways of sunlight reduction are fiber end melting method and diffuser scattering method. Through the analysis of these two methods, diffuser scattering method is selected and in doing so, the range of the scattering of the light side can be diffused and the environment can be beautified as well, offering comfortable visual effects. In this method, light can be brought to anyplace where lighting is in need according to our needs.After the accomplishment of the design of solar-tracking fiber light guide lighting system, the following steps are conducted according to the design, i.e., testing on tracking sun-precision performance, condenser performance measurement, measurement of the coupling efficiency and performance testing on heat sink strainer. Before the testing on tracking sun-precision performance, a level is used for the horizontal direction positioning and a compass for the south direction positioning. Finally, the experiment shows that the solar-tracking fiber light guide indoor lighting system being studied, with high rotation precision of the tracker, good stability and high efficiency of solar energy coupling, is roughly in line with the design goals.