Photodiode Vs Solar cell | Difference between Photodiode and Solar cell
This page compares Photodiode Vs Solar cell and mentions difference between Photodiode and Solar cell. This question is often asked in class 12 viva during physics practical examinations.
Introduction: Both photodiode and solar cell are photovoltaic semiconductor devices. Both of these devices receive light as input and generate respective outputs as per their application usage. Both are optoelectronic junction devices.
Photodiode
• It is a p-n junction diode designed such that light fall on it through the transparent window.
• When Photodiode is illuminated with light energy (hv) greater than energy gap (Eg), it generates
electron-hole pairs due to absorption of photons. e-h pairs are generated near depletion region of the photodiode.
• It generates current through external load when it is reverse biased.
• The magnitude of generated photocurrent depends on incident light intensity.
• Figure-1 depicts symbol of the photodiode. I-V characteristic of photodiode is shown below.
• Photodiodes are used in cameras, CAT scanners, smoke detectors, barcode scanners, fiber optic links etc.
• Refer basics and types of Photodiodes >>.
Solar cell
• It is a p-n junction device which generates emf when light radiation falls on its junction.
Photon energy of light should be greater than band gap.
• It does not require external bias for its functioning.
• It is used to produce more power and hence junction area is kept larger.
• Semiconductor materials with band gaps close to 1.5eV are used for solar cell manufacturing.
The materials having higher optical absorption, high electrical conductivity are chosen for its facrication.
• Solar cells are mainly used in satellites, space vehicles, calculators, back up power in homes etc.
• Figure-2 depicts working of the solar cell >>.
I-V characteristic of solar cell is shown below.
Difference between photodiode and Solar cell
Following table summarizes difference between photodiode and solar cell with respect to various parameters.
| Parameters | Photodiode | Solar cell |
|---|---|---|
| Junction area | Smaller | Larger, as solar radiation is required to fall on large area for conversion to electricity. |
| Biasing | Reverse bias voltage is applied to the photodiode externally. | No voltage is applied directly to the solar cell. |
| Size | Small | Large |
| Load capacity | Smaller | Greater |
| I-V characteristic |  |
 |
| Application | Used as light sensors to detect presence of light. | Used as transducers to convert light energy into electric energy i.e. electricity. |
| Advantages and disadvantages | • Refer Photodiode >> | • Refer Solar cell >> |
Also refer following topics on photodiode and solar cell.
• Advantages and disadvantages of Solar Energy >>
• Advantages and disadvantages of Perovskite Solar Cell >>
• Advantages and disadvantages of Organic Solar Cell >>
• Difference between Photodiode and Photoresistor >>.
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