13 Jul 2026
I-V Characteristics and Efficiency of a Solar Cell
practical
pg-i
solar-cell
photovoltaic
Aim
To plot the illuminated I-V characteristic of a solar cell and determine its open-circuit voltage, short-circuit current, fill factor, and efficiency.
Apparatus
Solar cell, lamp, variable load, voltmeter, ammeter, and lux or irradiance meter.
Figure
Theory
Photons with sufficient energy create electron-hole pairs in the semiconductor. The built-in field of the junction separates these carriers and produces a photocurrent. The useful output power is $P=VI$. If $V_{oc}$ and $I_{sc}$ are the intercepts and $(V_m,I_m)$ is the maximum-power point,
\[FF=\frac{V_mI_m}{V_{oc}I_{sc}},\qquad \eta=\frac{V_mI_m}{P_{in}}\times100.\]Observations
| Voltage (V) | Current (mA) | Power (mW) |
|---|---|---|
| 0.00 | 82.0 | 0.0 |
| 0.20 | 75.0 | 15.0 |
| 0.40 | 61.0 | 24.4 |
| 0.55 | 42.0 | 23.1 |
| 0.65 | 0.0 | 0.0 |
Graph
Result
$V_{oc}=0.65\,\text{V}$, $I_{sc}=82\,\text{mA}$, and the maximum power is approximately $24.4\,\text{mW}$. With incident power $P_{in}=0.20\,\text{W}$, $\eta=12.2\%$.
Viva Questions
- What is the photovoltaic effect? Generation of emf when light creates and separates charge carriers in a junction.
- What is fill factor? The ratio of maximum electrical power to $V_{oc}I_{sc}$.
- Why does current fall with load voltage? The load extracts the photogenerated carriers and changes the operating point.
Discussion