聚光型太陽光電(concentrating photovoltaic, CPV)系統是將聚光模組搭載於追蹤器上，使其能精準的正對太陽，讓陽光聚焦於太陽電池上發電。當聚光模組的聚光率越高，對於追蹤器的追日精度要求也越高，否則會因追日偏差造成太陽光電系統的發電量劇降。通常追日偏差角要求低於0.5o。 本文將位置感應裝置PSD (position sensitive device)搭配雙軸追蹤器來開發一混合式追日控制系統，包括利用Labview撰寫PSD訊號接收程式搭配太陽位置演算法為一混合式追日控制程式。先以太陽位置演算法驅動追蹤器大略追蹤太陽位置，再將PSD量測的追日偏差角回授至混合式追日程式中進行即時精密修正，如此可將平均追日偏差角由0.52o降至0.014o。 同屬本實驗室的劉智維(2010)發展的指向誤差模型的追日技術，受限於有限的戶外測試時間，並無法完整評估此項技術。因此本文進行指向誤差模型的長時間戶外追日測試（從2010年6~12月），追日偏差大致都維持在0.1-0.2o以下。 本文將PSD量測的電壓值與直射日照量進行線性迴歸分析，發現二者有合理相關性可將電壓值轉換為直射日照量，使PSD兼具量測直射日照的功能，量測直射日照量的準確度在晴天和多雲天候的誤差分別為5.4%和8%。 The layout of concentrating photovoltaic (CPV) system with installing CPV module on the dual-axis sun tracker in order to allow CPV modules point precisely to sun and generate electricity by focusing sunlight onto the solar cell. Higher concentration ratio requires increasing accuracy of sun-tracking, otherwise the output power of module will drop sharply due to tracking offset. Usually, a value smaller than 0.5o offset-angle is required. This study integrates PSD (position sensitive device) devices and dual-axis sun tracker to developing a hybrid sun-tracking control system, which consists of using Labview coding for PSD signal receiving program, integrating with the sun position algorithm to develop a hybrid sun-tracking control program, Initially the sun position algorithm (SPA) computes the sun position and drive tracker roughly tracks sun. Next the offset-angle measured by PSD is feedback to SPA for precise correction in real-time tracking. Using this method to implement hybrid sun tracking control can reduce the mean offset-angle from 0.52o to 0.014o. Jhih-Wei Liou (2010) from our lab, he developed the pointing-error correction model for sun-tracking., Due to limited time of outdoor test, this technique did not have complete assessment. Thus, this study carry out a longer outdoor test (from June to December in 2010) for sun-tracking using pointing-error correction model, satisfactory results is obtained (the offset-angle maintained smaller than 0.1-0.2o). This study performs linear regression analysis of measured voltage from PSD with direction normal irradiation (DNI). It is found reasonable correlation exists between these two values and allow one converts voltage value to DNI. In this way, PSD can also be used as pyrheliometer for measuring DNI. The measured mean error of DNI at sunny day and cloudy is 5.4% and 8%, respectively.
