How does a solar module work?

A solar module consists of several solar cells that convert sunlight into electricity. The main component of solar cells is a semiconductor material, usually silicon. Semiconductors are materials that cannot be assigned to the group of isolators or conductors and whose electrical properties can be altered by the deliberate, controlled introduction of impurities (doping). The solar cell consists of two adjacent semiconductor layers which feature separate metal contacts. These have each been doped in such a way, that an n-layer (n=negative) with an excess of electrons and an underlying p-layer (p=positive) with a shortage of electrons has emerged. Due to the concentration gradient, electrons diffuse from the n- to the p-layer. As a result, an electric field is formed inside this semiconductor structure, the so-called depletion zone.

In a solar cell, the upper n-layer is very thin. Therefore, the photons of the incident sunlight can penetrate the layer and transfer its charge to an electron in the depletion zone. The excited electron is mobile, follows the internal electric field and thus moves from the depletion zone to the metal contacts of the n-layer. When a consumer is connected, the circuit is closed: The electrons flow through the consumer to the back-side contact of the solar cell and finally to the depletion zone.