Question

Explain the working principle of a solar cell. Mention its applications.

Answer 1

                    Cross-sectional view of a solar cell

1. Solar cell converts light energy directly into electricity or electric potential difference by the photovoltaic effect.

2. It generates emf when radiations fall on the p-n junction. A solar cell is of two types p-type and n-type.

3. Both types use a combination of p-type and n-type silicon which together forms the p-n junction.

4. In solar cells, electron-hole pairs are generated due to the absorption of light near the junction.

5. Electrons move towards n-type silicon, holes move towards the p-type silicon layer.

6. Electrons reaching the n-side are collected by front contact and holes reaching p-side are collected by back electrical contact.

7. Thus potential difference is developed across solar cells. When an external load is connected, photocurrent flows through it.

8. Many solar cells are connected in series or parallel to form solar panels or modules.

Applications:

1. Widely used in calculators, watches, toys, portable power supplies, etc.
2. Used in satellites and space stations.
3. Solar panels are used to generate electricity.