太陽能電池的發電量與陽光的入射角度有相當大的關係，若要發揮太陽能電池的最大發電效率，就必須仰賴追日控制器使太陽能電池能隨時正對太陽，市面上常見的追日控制器有利用光感測器的主動式追蹤法或是計算太陽軌跡公式的被動式追蹤法，兩種控制器各有不同的優缺點，但光感測器追蹤法必須克服安裝上的誤差問題，而太陽軌跡公式追蹤法在定位時要達到精準也有相當大的難度，並且太陽能電池在長時間使用後，老化產生的機構變形，不但會降低發電效益，也會提升維護的成本 本研究在無遮陰時利用太陽能電池本身的短路電流作為追蹤訊號；在光線不足的情況下切換到太陽軌跡公式追蹤法，如此一來不需安裝額外的感測器也沒有安裝誤差的問題，更可以在機構變形的情況下找到發電效率最佳的位置。 本研究將自行設計的控制器與市面上販售的光感測器追日控制器，安裝於相同的追蹤器上進行追日效果的比較。由結果可以證明，本研究所設計的短路電流配合太陽軌跡公式混合控制器在PV系統上有相當不錯的性能表現。The amount of power generated by a solar cell is highly related to the angle of the solar panel and sunlight incident. The solar system can effectively generate a maximal amount of electricity when the solar panel is vertical to the sunlight. There are two commonly used methods to track the sun path, which are installing a photo-sensor on the track, and applying a sun trajectory formula. However, installing a photo-sensor exactly parallel to solar module and determine an accurate initial tracking point are difficult. The installing bias and locating bias may cause the solar module being not able to directly receive the sunlight. In addition, the shape of solar module may be different from the original one after a lone time used. The bending shape of the solar module not only leads to the decreasing efficiency of generating electricity, but also the higher maintenance cost. This study proposes a sun path tracking method based on the short-circuit current and the sun trajectory formula. Without the influence of cloud, the short-circuit current of a solar cell can be used as a tracking signal which can detect the sunlight and find the best location with highest efficiency for generating electricity even though the solar module becomes out of the original shape. When the sunlight is insufficient, a sun trajectory formula is adopted to tracking the sun path. Thus, without using the photo-sensor, there is no installing problem happened in this proposed method. A comparison between the performance of the controller which adopts the proposed method in this study and the performance of the controller product sold in market with a photo-sensor for tracking sun path is presented in this study. By installing the two controllers on a same sun tracker, the experiment results show that the proposed method can perform as well as the controller product which has been sold in market.
