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太陽光發電系統介紹 Solar cell 篇 Motech Industries Inc. 1 Solar cell 種類 種類 1.Crystalline silicon solar cell A. Monocrystalline B. Multicrystalline 2.Thin film solar cell A. Amorphous silicon B. Polycrystalline materals C1. Cd Te C2. Copper indium diselenide (CIS or CIGS) 備註 88% Market 數百 microns C-Si 12% Market 1 micron a-Si (amorphous) 金屬與另一惰性金屬接觸 時所產生之電化腐蝕現象 2 Solar Cell 製作 A. 將n-type摻雜,塗佈在p-type之表面。 B. 印刷導引線(光與電阻性損失最小) 最大光吸 收及電流收集。 Silica (SiO2) Mono CZ 冶金級 silane FZ 單晶矽晶碇 複晶矽 98%pure 10-9 高溫去氧化 拋光 電極網印 清洗 燒結 蝕刻 鍍錫 表面處理 P/N擴散 電漿蝕刻 切割 抗反射 模沈積 Solar Cell 3 Solar cell 比較 矽 化合物 染料 Single 15~24 price B Multi 10~18 A A a-Si 8~13 A+ A GaAs 19~32 B- A+ CdTe 10~15 A A CuInSe2 10~12 A A TiO2 7~11 A+ B 2以下 A+ B- 有機半導體 信賴度 A+ 4 PV Module Performance Rating 測試環境 1. The peak watt (Wp) rating A. Temp B. Solar radiation (AM1.5) 但如此實驗室的狀態不實際。 2. NOCT-normal operating cell temperature 在一定之室外溫度下所測得之最大功率,雖較 Wp 為低,但較真實。 3. AMPM standard global-average day : light level, ambient temperature, air mass 5 Electrical Performance 1. Power Output:一天內產生之peak power or avg power。 (watts) 2. Energy Output: (Wh) A B C Wh/m2 Wh/Kg Wh/$ 在一定之週期下評估以上3項目 3. Conversion efficiency: energy output from array energy input from sun x 100% 評價單位:1EEE、ASTM (American Society for Testing and Materials) 6 影響日照的因素 7 光波頻譜 8 2ND Quadrant: Generation I 1ST Quadrant: Dissipation V 3D Quadrant: 4TH Quadrant: Dissipation Generation Power is either generated or dissipated, depending on the quadrant you are in. 9 I Power Dissipating Region V Power Dissipating Region Dark Characteristic I V Power Generating Region 10 Light Characteristic The VI characteristic of a solar cell is usually displayed like this: V I V I The coordinate system is flipped around the 11 voltage axis. Power is a function of position along the VI characteristic. At the intercepts, it is minimum - zero - increasing to a max near the knee of the curve. 12 Set #1: ISC , PMAX , VOC ISC (0V, 150 mA) V I = 0 mW PMAX (0.43 V, 142 mA) V I = 61 mW Some typical values (0.5V, 0 mA) V I = 0 mW VOC 13 The short circuit current ISC is a linear function of sunlight intensity. The open circuit voltage VOC is not. (VOC is weakly dependent on temperature.) Recall from Part I that sunlight intensity is measured in terms of a solar constant with units such as mW/cm2. 14 Answer to Question #1: I = ISC R = 0 Does it surprise you that the current at short circuit is not infinite? Or that a current can flow with no voltage? Where 15 does the energy originate? Answer to Question #2: I = 0 R = + _ V = VOC 16 Answer to Questions #3 and #4 (cont’d): Current at max power ISC Hyperbola for P = PMAX Point of tangency Voltage at max power VOC 17 Set #2: RS , RSH ISC RSH The slopes of these lines are characteristic resistances. RS VOC 18 Questions: 1. Which resistance is higher, the measurement at ISC or the measurement at VOC ? Remember: R = V/I ! 2. Physically, what do you think these resistances represent? 3. As a solar cell designer, what is your preferred ideal value? 19 Answers to Questions #1 - #3: The resistance at ISC is extremely high. In an equivalent circuit model of a solar cell, it represents a shunt resistance. The resistance at VOC is extremely low. In an equivalent circuit model of a solar cell, it represents a series resistance. Both of these resistances are internal, and represent energy dissipation mechanisms in the cell. Ideally, a designer would like zero series resistance and infinite shunt resistance. 20 Cell RS ISC RSH RLOAD Cell Equivalent circuit for a solar cell with load. Internal resistances RS and RSH represent power loss mechanisms inside the cell. 21 RS = 0 ISC RSH = RLOAD The ideal solar cell would have no internal losses at all! What would the VI characteristic of THIS cell look like? 22 The Ideal Solar Cell ISC RSH = RS = 0 VOC 23 The Ideal Solar Cell ISC Notice that the area under the rectangle = PMAX for the ideal cell. For this cell, PMAX = VOC ISC VOC 24 Set #3: Fill Factor ISC In fact, PMAX/(ISC VOC) measures the cell’s quality as a power source. The quantity is called the “Fill Factor.” Can you see why? VOC 25 Questions: 1. What is the ideal fill factor? 2. Can the ideal cell ever be built? Why or why not? 3. For a cell with these parameters: (0V, 150mA), (0.43V, 142mA), and (0.5V, 0mA) calculate the fill factor. 26 Answer to Question #1: The ideal fill factor is unity. Why? Answer to Question #2: An ideal cell might be approximated, but never actually built. Nature is never ideal as humans think about “ideal.” Answer to Question #3: The fill factor is: (0.43V 142mA)/(0.5V 150mA) = 0.81 = 81% 27 太陽光發電系統介紹 Inverter 篇 Motech Industries Inc. 28 變流器技術 太陽光電池與電池產生直流電壓與電流, 然而負載所需為交流功率時,那麼就需 要Inverter來轉換DC/AC,一般來說可利 用Inverter轉換DC電源成為交流單/三相、 50/60Hz、117/220V,而轉換功率可從 數百Watts到數千KWatts,較大功率輸出 的Inverter其輸出電壓可達480V甚至更高。 29 Inverter種類 種類 1. 獨立型 A. 弦波 B. 修正弦波 C. 方波 2.併聯型 A. 單一MPPT B. 多個MPPT 3.混合型 備註 30 變流器的功率額定 1.功率是時間的函數 2.突波功率 3.溫度對額定功率的影響 31 變流器的效率 1.效率視負載而定 2.電感性對電阻性負載 3.效率測量的設定 32 變流器的波形 1.方波 2.修正方波或修正弦波 3.弦波 33 變流器電路 1.先變頻再變壓 2.先變壓再變頻 3.波寬調變 4.多工變壓器 34 市電併聯混合型變流器 More flexibility on power management. Provides limited power for critical loads incase of power failure. Requires Battery maintenance schedule. 35 變流器特徵總合 AC OUTPUT PARAMETERS DC INPUT PARAMETERS PROTECTION GENERAL SPECIFICATION 36 AC OUTPUT PARAMETERS Output Voltage Output Frequency Continues AC output rating Waveform Output Power Factor THD DC control injection Efficiency 37 DC INPUT PARAMETERS Input Power control MPPT Range 38 PROTECTION Internal Protection System Anti islanding Protection signals/contacts Internal Shutdown 39 GENERAL SPECIFICATION 1 Parallel Operation Local Operator Interface Front Panel LCD Display Computer Ports Isolation Remote Access Parameters Fault log Communications 40 GENERAL SPECIFICATION 2 Output Date Files Operating Temperature Rang Humidity Enclosure Printed Circuit Boards Standby Tare Losses Noise Aux. ADC Port 41 選擇變流器特性之進一步探討 1.直流輸入電壓 2.電壓調整率 3.可服務性 4.臨界點調整 5.併聯成較大功率源 42 選擇變流器特性之進一步探討 43