1. Applications of Photovoltaic Technologies

2. Solar Cell-structure A solar cell is a P-N junction device
Light shining on the solar cell produces both a current and a voltage to generate electric power.
Busbar
Antireflection coating
Fingers
Emitter
Antireflection texturing
(grid pattern)
Base
Rear contact

3. I-V Tester

4. Irradiance inhomogeneity
Illumination Sources
Class
Spectral Match
Irradiance inhomogeneity
Temporal Instability
Long Term
Short Term A % 2%
0.5% B % 5% C %
10%
Table: Solar simulator classification according to IEC Ed. 2.0.

5. No Resistive Losses Solar Cell model The I-V relation is given as: I VID V IL
Io －dark saturation current ,
IL －light generated current. ,
n －ideality factor .

6. Solar Cell I-V Curve V I
I (diffu.) I0
A P-N junction in the dark consumes power, as it can be operated in 1st or 3rd quadrant
Under illumination solar cell can be operated in the fourth quadrant corresponding to delivering power to the external circuit
Effect of solar radiation on the I-V curve
Current in the illuminated solar cell is negative, flows against the conventional direction of a forward diode

7. Solar Cell I-V Curve Solar cell parameters I Isc Pm Im V
Voc - open circuit voltage,
Isc - short circuit current,
Pm - maximum power point
Im, Vm – current and voltage
at maximum power point
FF – fill factor
η – efficiency
Rs – series resistance
Rsh – shunt resistance
Isc I Vm Im
Voc Pm V
Usual I-V plot of solar cell – Current is shown on positive y -axis

8. Short-Circuit Current, IscVm Im
Voc Pm X
The short-circuit current is the current through the solar cell when the voltage across the solar cell is zero (i.e., when the solar cell is short circuited).
The short-circuit current is due to the generation and collection of light-generated carriers.
The short-circuit current is the largest current which may be drawn from the solar cell.
At V=0  I = -IL= Isc

9. Open Circuit Voltage: Voc
Isc I Vm Im Pm X
Voc
The open-circuit voltage, Voc, is the maximum voltage available from a solar cell, and this occurs at zero current.
The open-circuit voltage corresponds to the amount of forward bias on the solar cell junction due to illumination.
At I=0  V = Voc

10. Maximum power: Pm I Isc Pm Im Pm = Im x Vm
Power out of a solar cell increases with voltage, reaches a maximum (Pm) and then decreases again. Im
Power Vm
Voc
Pm = Im x Vm
Remember we get DC power from a solar cell

11. Fill Factor: FF I Im Ideal diode curve Isc
The FF is defined as the ratio of the maximum power from the actual solar cell to the maximum power from a ideal solar cell Pm Im Vm
Voc
Graphically, the FF is a measure of the "squareness" of the solar cell

12. Efficiency: η I Isc Pm ImVm Im Pm X
Voc
Power
Efficiency is defined as the ratio of energy output from the solar cell to input energy from the sun.
The efficiency is the most commonly used parameter to compare the performance of one solar cell to another.
Efficiency of a cell also depends on the solar spectrum, intensity of sunlight and the temperature of the solar cell.

13. Four Point Probe Resistivity Measurements

14. Characteristic resistance, Rch
Effect of Rs and FF
Isc
Voc V I
Characteristic resistance, Rch
Medium Rs
Large Rs
Normalized series resistance, rs
Slope of the I-V curve near Voc gives indication about Rs
Effect of series resistance on the FF and maximum power

15. Effect of Rsh on FF Isc Normalized shunt resistance, rsh Medium Rsh I
Voc V I
Normalized shunt resistance, rsh
Medium Rsh
Slope of the I-V curve near Isc gives indication about Rsh
Effect of series resistance on the FF and maximum power

16. ScienceTech 150W太陽光模擬器 機型：ScienceTech 150W太陽光模擬器與IV 量測系統
Substrate：> 5.0 cm x 5.0 cm
可量測範圍：0.1V to 1.0V
I-V曲線中之各項性能參數：開路電壓（Voc）、短路電
流（Isc）、最大輸出功率（Pmp）、並自動計算填充因子(fill factor) 、太陽電池效率(efficiency)
具有溫控功25℃

17. ScienceTech

18. IV measurement

19. IV Analysis

20. 全波段入射光子轉換效率光度計(IPCE)

21. Quantum Efficiency
Quantum efficiency (Q.E.) is the ratio of the number of carriers collected by the solar cell to the number of photons of a given energy incident on the solar cell.
Internal quantum efficiency (IQE) refers to the efficiency with which photons that are not reflected or transmitted out of the cell can generate collectable carriers.
External quantum efficiency (EQE) of a silicon solar cell includes the effect of optical losses such as transmission and reflection.

22. Quantum Efficiency