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Question
Explain the three processes involved in the working of a solar cell.
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Solution
A solar cell is a junction of n-type silicon (blue) and p-type silicon (red).
It generates electricity by using sunlight to make electrons move across the junction between the different types of silicon:
- When sunlight shines on the cell, photons bombard the upper surface.
- The photons carry their energy from the n-type layer to the p-type layer through the p-n junction of the cell.
- The photons transfer their energy to electrons in the p-type layer.
- The electrons use this energy to move across the barrier into then-type layer and flow out into the circuit.
- This flow of electrons through the circuit gives rise to a flow of current in the external circuit.
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