應用基因演算法於太陽能電池傾斜角之最佳化設計

Optimization of Tilt Angle for Photovoltaic Modules by Genetic Algorithm

石化能源逐漸短缺，環境污染問題日益嚴重，利用太陽能電池發電將是解決未來能源不足的重要途徑。為提高太陽能電池的輸出功率，其安裝角度應隨裝設地點不同而調整。本文選取台灣七個城市，先利用儒略計時公式，計算出任何時問地點的太陽位置與天空晴朗時的日照強度，並考慮各地區溫度之不同，以基因演算法求出固定式太陽能電池的最佳安裝角度與電能輸出。結果顯示七個城市全年最佳傾斜角分別為：台北23.15°、台中22.2°、台南21.14°、高雄20.78°、恆春20.16°、花蓮22.15°及台東20.93°，此角度與當地緯度略有差距，而太陽能電池之轉換效率則介於13.08%~13.61%之問，太陽能電池功率輸出與輻射量呈正相關，亦即用輻射量或用功率輸出為目標函數所得最佳傾斜角相當接近；為驗證本研究之可行性，擬從2006年四月至2007年三月之一年時問於南投地區進行實測分析，分別裝設6片不同傾斜角度之固定式太陽能電池，記錄分析各片電池之電力輸出，其結果可以提供固定式電池安裝之參考，並且能進一步推廣至建築整合型太陽能電池裝設時之角度評估。

Due to the shortage of fossil energy and the serious environmental pollution problems, in the future, energy from photovoltaic cells will become more important. In order to enhance the electric power output, the tilt angle of cell modules should be adjusted according to the climatic conditions as well as the latitude of the site where the cell modules have been installed. In this study, seven Taiwanese cities were selected for analysis. First, the position of the sun at any time and location was predicted by the mathematical procedure of Julian dating; then, the irradiation was obtained at each site under a clear sky. By considering this data with the temperature effect, a genetic algorithm was adopted to calculate the tilt angle and output power for fixed south-facing PV modules. The results show that the annual optimal angle for the Taipei area is 23.15°; for Taichung, 22.2°; for Tainan, 21.14°; for Kaosiung, 20.78°; for Hengchung, 20.16°; for Hualian, 22.15°; and for Taitung, 20.93°. The conversion efficiencies are between 13.08% and 13.61%. In order to confirm the computer simulation results, experiments were conducted for determining the optimal tilt angle of the PV modules. Six fixed south-facing PV modules with different tilt angles were selected. The experiment was carried out at Nantou city in Taiwan from April 2006 to March 2007. A PC-based data-acquisition system was built to automatically record each PV module's voltage, output current, output power, temperature and solar irradiation. The results also show us that the optimal tilt angles were very similar whether the electric power or the irradiation was used as the objective function. Hence, the tilt angle of the fixed structure modules should be carefully evaluated for different places and periods of time ill order to obtain the maximum overall output power.