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太陽光發電系統介紹

Solar cell 篇

Motech Industries Inc.

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Solar cell 種類

種類 備註1.Crystalline silicon solar cell A. Monocrystalline B. Multicrystalline

88% Market數百 micronsC-Si

2.Thin film solar cell A. Amorphous silicon B. Polycrystalline materals

12% Market1 microna-Si (amorphous)

C1. Cd Te C2. Copper indium diselenide (CIS or CIGS)

金屬與另一惰性金屬接觸時所產生之電化腐蝕現象

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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)

高溫去氧化 冶金級98%pure

Monosilane

複晶矽 單晶矽晶碇10-9

CZFZ 切割

拋光 清洗 蝕刻 表面處理 P/N擴散 電漿蝕刻 抗反射模沈積

電極網印 燒結 鍍錫 Solar Cell

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price 信賴度

矽Single 15~24 B A+

Multi 10~18 A A

a-Si 8~13 A+ A

化合物GaAs 19~32 B- A+

CdTe 10~15 A A

CuInSe2 10~12 A A

染料 TiO2 7~11 A+ B

有機半導體 2 以下 A+ B-

Solar cell 比較

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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

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1. Power Output ：一天內產生之 peak power or avg power 。 (watts) 2. Energy Output ：

(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

評價單位： 1EEE 、 ASTM (American Society for Testing and Materials)

A B C

Wh/m2

Wh/Kg Wh/$

x 100%

Electrical Performance

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影響日照的因素

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光波頻譜

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V

I

Power is either generated or dissipated, depending on the

quadrant you are in.

1ST Quadrant:

Dissipation

3D Quadrant:

Dissipation

2ND Quadrant:

Generation

4TH Quadrant:

Generation

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IV

Dark Characteristic Light Characteristic

I

V Power Generating Region

Power Dissipating

Region

Power Dissipating Region

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The VI characteristic of a solar cell is usually displayed like this:

V

IV

I

The coordinate system is flipped around the voltage axis.

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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.

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Set #1: ISC , PMAX , VOC

(0.5V, 0 mA) V I = 0 mW

(0.43 V, 142 mA) V I = 61 mW

ISC

VOC

PMA

X(0V, 150 mA)

V I = 0 mW

Some typical values

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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.

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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 does the energy originate?

Answer to Question #1:

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I = 0

R =

Answer to Question #2:

+

_V = VOC

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ISC

VOC

Hyperbola for P = PMAX

Point of tangency

Voltage at max power

Cu

rren

t at

max p

ow

er

Answer to Questions #3 and #4 (cont’d):

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Set #2: RS , RSH

ISC

VOC

The slopes of these lines are characteristic resistances.

RSH

RS

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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?

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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.

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ISC

RS

RSH

RLOAD

Equivalent circuit for a solar cell with load. Internal resistances RS and RSH represent power loss mechanisms

inside the cell.

Cell

Cell

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ISC

RS = 0

RSH =

RLOAD

The ideal solar cell would have no internal losses at all! What would the VI characteristic of THIS cell look like?

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ISC

VOC

RSH =

RS = 0

The Ideal Solar Cell

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Notice that the area under the rectangle = PMAX for the ideal cell.

For this cell,PMAX = VOC ISC

ISC

VOC

The Ideal Solar Cell

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ISC

VOC

Set #3: Fill Factor

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?

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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.

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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%

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太陽光發電系統介紹

Inverter 篇

Motech Industries Inc.

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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。

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Inverter 種類種類 備註

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

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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

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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

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變流器的波形 1. 方波 2. 修正方波或修正弦波 3. 弦波

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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

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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.

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變流器特徵總合 AC OUTPUT PARAMETERS DC INPUT PARAMETERS PROTECTION GENERAL SPECIFICATION

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AC OUTPUT PARAMETERS Output Voltage Output Frequency Continues AC output rating Waveform Output Power Factor THD DC control injection Efficiency

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DC INPUT PARAMETERS

Input Power control MPPT Range

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PROTECTION

Internal Protection System Anti islanding Protection signals/contacts Internal Shutdown

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GENERAL SPECIFICATION 1

Parallel Operation Local Operator Interface Front Panel LCD Display Computer Ports Isolation Remote Access Parameters Fault log Communications

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GENERAL SPECIFICATION 2 Output Date Files Operating Temperature Rang Humidity Enclosure Printed Circuit Boards Standby Tare Losses Noise Aux. ADC Port

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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

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選擇變流器特性之進一步探討