| 摘要: | 本文探討中壢地區單/雙軸追日PV系統性能，由於雙軸PV系統實驗數據有限，故以PVsyst軟體模擬單/雙軸追日PV系統年度發電量，並將結果和實驗數據比較，驗證模擬可靠性。在雙軸追日控制上，比較中央大學團隊開發的短路電流追日與億芳光感測器之PV系統性能，最後藉由I-V特性曲線量測探討PV模組於戶外運作的實際性能。雙軸追日PV系統部分，實驗組採用短路電流方法（安裝於tracker A），記錄的日均追日偏差角範圍為0.37o~0.68o，對照組採用光感測器的億芳控制器（安裝於完全相同型式的tracker B），得到的日均追日偏差角範圍為0.09o~0.2o，雖然短路電流的追日精度不如億芳光感測器，對PV系統而言，發電量才是決定系統性能的最終指標，兩者六天累積發電量分別為56.14 kWh及55.73 kWh；二者表現無分軒輊但是短度電流方法相較於光感測方法有不少優點（例如可補償追蹤器的機構變形、安裝及機構裝配造成的各種誤差），故它為實用有效的追日方法。單軸追日PV系統四年平均年發電量為835 kWh/kWP，2009年性能比為80.1%，2011年性能比降至59.5%，顯示PV系統有老化和機件故障的情形發生。本文使用平均氣象年的概念模擬單/雙軸追日PV系統發電量，模擬雙軸PV系統tracker A和B和單軸PV系統的年發電量分別為1121、1128和1073 kWh/kWP/year， kWh/kWP/year，以本文的例子，雙軸相較於單軸年度發電量增益為5.17%。量測I-V特性結果顯示日照量上升導致最大功率輸出增加，主要影響PV模組的短路電流；模組溫度上升會使最大功率輸出降低，主要影響PV模組的開路電壓。This study presents performance of one/two-axis tracking photovoltaic (PV) system in Jhong-Li. Due to limited experimental data of two-axis PV system, simulation annual electricity of one/two-axis PV system with PVsyst software was used. Experimental data were compared and validated simulation reliability. In two axis sun-tracking control, comparison of the approach of short-circuit current tracking, developed by National Central University and active tracking sensor produced by EVERPHOTON Energy were made. Finally, evaluation of outdoor PV module performance by measure I-V characteristic of module was provided.In two-axis tracking PV system, short-circuit current tracking control which installed on tracker A, has a daily average offset angle between 0.37o to 0.68o. Another identical Tracker B with controlled by EVERPHOTON Energy tracking sensor, recorded a daily average offset angle between 0.09o to 0.2o. Though the tracking accuracy of short-circuit current control is not better than EVERPHOTON Energy tracking sensor. As for assessing the performance of PV system, electricity is the ultimate factor. Accumulated electricity of six days for trackers A and B are 56.14 kWh and 55.73 kWh, respectively. Both tracking methods were performed equally, yet the short-circuit current control has several advantages (e.g., can compensate errors due to mechanism deformation, installation and assembly of tracker). Therefore, it is a practical and effective sun-tracking method. In the average yearly electricity for one axis tracking PV system is 835 kWh/kWP based on four year records. Its performance ratio in 2009 was 80.1%, and dropped to 59.5% in 2011, which shows degradation and mal-function of PV system.This study uses average meteorological year data to simulate electricity of one/two-axis tracking PV system. The predicted electricity for both two-axis trackers A and B and one-axis PV system are 1121, 1128 and 1073 kWh/kWP/year, respectively. In this case, electricity gain for two-axis PV over one-axis PV system is 5.17%.Results of I-V characteristic measurement show that the increase of solar irradiation causes increase of maximum power output and affects the short-circuit current of PV module. While the increase of module temperature causes decrease of maximum power output and affects open-circuit voltage of PV module. |
