From ingot to cell: how a photovoltaic cell is made

Every solar panel on a rooftop or in a solar park starts with a small, thin component: the photovoltaic cell. In our animation we follow, step by step, the path from very pure silicon to the cell that turns light into electricity. Below are the same steps, explained in words.

1. Polysilicon: the raw material

It all starts with polysilicon, chunks of high-purity silicon. Silicon is one of the most abundant elements in the Earth's crust, but solar cells need it to be extremely pure, because impurities slow electrons down and reduce the current a cell can deliver. The polysilicon chunks are loaded into a crucible, a vessel that withstands very high temperatures, where they melt and become liquid.

2. The ingot: one large crystal

A single large crystal, called a monocrystalline ingot, is slowly pulled from the molten silicon. Textbooks describe the process like this: a seed crystal touches the melt and is raised very slowly while rotating, and the silicon solidifies on it, keeping the same ordered crystal lattice. An ordered structure, without boundaries between crystals, lets electrons move through the material more easily.

3. The wafer: very thin slices

The cylindrical ingot is shaped into an almost square block and then wire-sawn into slices a fraction of a millimetre thick. These slices are called wafers, and each one becomes the base of a cell. After sawing, the wafers are cleaned and prepared for the steps that turn a plain slice of silicon into an electrical device.

4. Texture: pyramids that trap light

A perfectly smooth silicon surface would reflect part of the light falling on it. That is why the wafer surface is textured with microscopic pyramids, too small to see with the naked eye. Light reflected by one pyramid hits the neighbouring one and gets a second chance to enter the silicon. In the animation, the magnifying glass shows exactly this detail.

5. The cell, layer by layer

Thin layers are added to the wafer, each with its own role. The exploded view in the animation numbers them from top to bottom:

1. Front contact grid - fine metal fingers and busbars that collect current from the front of the cell while leaving as much surface as possible open to light.
2. Anti-reflective coating - a very thin layer that reduces reflection and gives the cell its typical dark colour.
3. Silicon wafer - the heart of the cell, where light is absorbed.
4. Passivation layer - protects the silicon surface so that fewer electrons are lost before they are collected.
5. Rear contact - closes the electrical circuit on the back of the cell.

How the cell works

When sunlight hits the cell, its energy sets electrons in motion inside the silicon. The internal structure of the cell separates the electrical charges, the contact grid collects them, and when the cell is connected to a circuit an electric current flows. In the animation, the sun's rays light up a bulb: the simplest picture of this principle. Cells are then connected together and protected by glass and a frame, forming the solar panel.

Recap in 5 steps

Polysilicon, ingot, wafer, cell, panel. The cell is the step in the production chain that actually turns light into electricity.

Why it matters for Romania

SOLYWATT ROMANIA plans to make this step in Romania, through its planned TOPCon+ photovoltaic cell factory in Galati, with a capacity of 1.17 GW. European manufacturing, local skills, clean energy.