From photons to electrons [ Return towards Photovoltaic energy ]

Photovoltaic cells capture sunlight and convert it directly into electricity. These technologies enable energy to be produced without greenhouse gas emissions and limit our dependency on fossil fuels.

How does it work?

Photovoltaic energy in images

The core of a photovoltaic cell is comprised of a fine layer of silicon. Its upper and lower surfaces are "doped": these are the positive (P) and negative (N) layers.

When the light rays reach the cell, they transfer their energy to the excess electrons in the negative layer which move to the positive layer. The junction between these two layers creates a circulation of electrons from the N layer to the P layer: this is electricity.

Two main technologies exist to date for making photovoltaic cells. In the traditional or "crystalline" technology, ingots of silicon are cut into thin slices called wafers and transformed into photovoltaic cells. Crystalline technology is well-established and represents 85% of today's total market.

The thin layer technique represents 15% of the market and is rapidly growing. More innovative, it allows building cells on glass or other substrates. Through gases, elements are deposited on the support, successively forming the several layers.