How is a solar cell made

Solar cells - the central element of a solar system

How do solar cells work?

A solar cell converts solar energy into electricity. When sunlight hits the cell, positive and negative charge carriers are released in the cell. The light or heat can be transmitted via a so-called semiconductor. An ideal semiconductor is silicon, because it is inexpensive as a component of quartz sand and can be produced in a highly pure and monocrystalline manner. In order for the positive and negative charge carriers to be conducted correctly, foreign atoms are built into the semiconductor. Here one speaks of p- and n-doped silicon. The silicon layer p-doped with trivalent boron atoms has a positive charge excess, while the layer doped with pentavalent phosphorus atoms is negatively charged.

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The so-called layer is located between the p- and n-doped layers Boundary layer or the p-n junction: Here an internal electric field is generated by the impact of the two layers. When exposed to sunlight and the associated penetration of photons, electrons are separated from their atoms. These migrate into the n-layer, while "electron holes" that have become free move towards the p-layer. On the front and back of the cell, the electrons are diverted through contact layers made of metal (usually aluminum or silver) and made to flow through a conductor. Electric current flows.

You can find more information on how a solar cell works in this video from the Helmholtz Center Berlin:

An additional anti-reflective layer made of silicon nitride or titanium dioxide is applied to the solar cell to protect the cell from environmental influences and to reduce light reflections.

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What types of solar cells are there?

In general, three types of silicon cells for photovoltaic systems can be distinguished:

    Monocrystalline solar cells in close-up © PN_Photo |

  • Monocrystalline solar cells:
  • Monocrystalline solar cells are made from monocrystalline silicon rods, which are then cut into thin slices or Wafer get cut. This manufacturing process is very complex and expensive, but due to the high silicon content they are highly efficient. This is up to 20%. Monocrystalline cells are particularly worthwhile for small PV areas that should achieve the highest possible yield. You can read more about monocrystalline solar cells here.

  • Polycrystalline solar cells:
  • Polycrystalline cells are made from silicon blocks that have previously been cast and then solidified. As a result of the cooling process, the silicon crystals later have different sizes. The block is turned into discs or Ingots cut, which ultimately result in the cells. At 12 to 16%, the efficiency of polycrystalline cells is significantly lower than that of monocrystalline cells. They are therefore particularly suitable for large roof areas. The price, on the other hand, is much cheaper, which is why polycrystalline modules are also the most popular modules.

    Close-up of polycrystalline solar cells © PN_Photo |

  • Thin film solar cells:
  • While crystalline solar cells are produced on the basis of wafers, in the production of thin-film solar cells the semiconductor is vapor-deposited or sprayed onto a carrier made of glass, plastic or metal - this creates a micrometer-thick layer that absorbs sunlight. Amorphous silicon, cadmium telluride or copper indium diselenide are used as semiconductors. Amorphous means that the semiconductor atoms are in a disordered network and are therefore particularly reactive with other atoms, for example with hydrogen atoms. The advantage of thin-film modules: They are extremely light and, due to the low use of semiconductor material, they are also inexpensive to produce. Due to the different carrier materials, the modules can be used flexibly - from pocket calculators to clothing to photovoltaic systems. Since the cells have a rather low efficiency of 4 to 10%, they are more suitable for large PV areas.

Manufacturer of solar cells and modules

In the following you will find an overview of well-known German solar cell manufacturers and their products:

companyMonocrystallinePolycrystallineThin film
AE Solarxx 
aleo solarxx 
Alma Solarxxx
Schott Solarxxx
Solar-Fabrik AGxx 


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