立體太陽能焦點軌跡追蹤集能系統

Abstract

本研究以發展適應性更高的太陽能追蹤系統為主要目標，經由模擬發現四季的太陽焦點軌跡為特殊的曲面，因此設計出立體太陽能焦點軌跡追蹤集能系統。此系統包含：砷化鎵(GaAs)太陽能電池、太陽焦點軌機追蹤機構、菲涅爾透鏡(Fresnel lens)、三個步進馬達與其驅動器、六個極限開關、微控制器PIC18F4520。 本追蹤系統的特點有以下三點：(1)系統使用了透鏡的聚焦功能，增加了太陽能電池所吸收的太陽輻射能，但透鏡本身並不轉動或移動，而是只移動了體積小且質量輕的砷化鎵太陽能電池，以減少馬達的耗能。(2)可在立體空間中尋找非圓形之焦點所在位置。(3)直立式的設計，使機構可放置於大樓的牆壁上。 目前已得到系統的電池發電效率在中午時約在0.21％至0.81%而固定式的則是1.03%至2.48%；而在下午時系統的電池發電效率約在1.70%至2.47%而固定式的則是0.52%至0.78%。其原因是因為當菲涅爾透鏡直立放置時，在接近中午時的光線經過透鏡後被聚焦的量會比接近日落時經過透鏡後被聚焦的量要少很多，因此，才會有系統之發電效率在中午時比垂直放置的太陽能電池之發電效率要來得低的現象。此系統因為聚焦了507倍，所以將可減少99.8％之太陽能電池面積。由於透鏡的造價比太陽能電池低，因此，將可節省系統之造價。

The research develops a more robust solar tracker. Simulation shows that focusing trajectory of sun rays of four seasons form a special surface. Thus, a steric focal trajectory tracking solar collector is designed. The system contains a GaAs solar cell, a focusing trajectory mechanism, Fresnel lens, three stepping motors with their drivers, six limiting switches, and a microcontroller PIC18F4520. The tracking solar collector has the following features: (1) A Fresnel lens to concentrate light which lets the solar cell absorb more energy. The lens is kept fixed without the need to move or rotate, but instead, the solar cell with relative small size and light weight is driven by the motor. This design can reduce power consumption of the motor. (2) It can automatically find a non-circle focal point in the space. (3) Vertical design allows it to be put on the wall of a building. The efficiency of this solar cell system at noon is of about 0.21％ to 0.81% . It can be compared to a system fixed on the wall which is of about 1.03% to 2.48%. The efficiency of this solar cell system at sunset is of about 1.70% to 2.47% and can be compared to a system fixed on the wall which is of about 0.52% to 0.78%. The reason is that the energy of light focused through the lens is less at noon than at sunset when the Fresnel lens is placed vertical. This system’s concentration factor is 507, so it is capable of decreasing 99.8 percent of the solar cell’s area to achieve comparable system efficiency and therefore, the cost of this system can be reduced.