The working principle of a solar cell is based on the photovoltaic effect, where light is converted directly into electricity. Solar cells are made from semiconductor materials, usually silicon, which have the unique ability to generate electricity when exposed to sunlight. When sunlight strikes the surface of the solar cell, the energy from the light is absorbed by the semiconductor material. This energy excites the electrons in the silicon atoms, causing them to break free from their bonds and move around. This process generates electron-hole pairs, where free electrons are negatively charged, and the holes they leave behind are positively charged.
A solar cell consists of two layers of silicon: the p-type layer, which has an excess of holes, and the n-type layer, which has an excess of electrons. When these two layers are combined, they form a p-n junction that creates an electric field. This electric field directs the free electrons towards the n-type layer and the holes towards the p-type layer, allowing them to flow in a specific direction.
As a result, the movement of these electrons generates an electric current. Metal contacts are placed on both the top and bottom of the solar cell to capture the electrons, creating an external circuit through which the current can flow. The current produced is direct current (DC), which can be used immediately or converted to alternating current (AC) using an inverter for home or industrial use.
The efficiency of solar cells depends on the materials used and their ability to absorb sunlight and generate a current. Solar cells are a clean and renewable source of energy, widely used in applications from small devices to large-scale solar power plants, making them a crucial technology in the shift toward sustainable energy solutions.