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How does it work?

What is photovoltaic energy?

Photovoltaic energy is the conversion of sunlight into electric power. It is a renewable energy and can be used to power all types of electrical equipment or systems.

Photovoltaic energy can be used in two ways:

  • it is either connected to the electrical grid (for houses, large roofs on community buildings, etc.) and injected directly into the grid,
  • or it brings electricity to isolated sites (solar units, solar pumping, etc.) which immediately benefit from the necessary power.

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How is photovoltaic energy produced?

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To use the majority of electrical equipment, the direct current generated by the solar panels has to be converted into alternating current. This principle is applied via an inverter built into the photovoltaic solar installation.

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The main components of a photovoltaic solar system

Photovoltaic cells
A photovoltaic cell is an electronic component which generates electricity when exposed to light. The photovoltaic cell generates a direct current. Its power depends on the light received.

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Photovoltaïque : comment ça marche ?Cell manufacture process
The material used most frequently to manufacture these photovoltaic cells is silicon.
The raw silicon is obtained by reducing silica (the most abundant constituent part of the Earth's crust, especially in sand or quartz). It must then be cleaned and reworked. It is then produced in ingot form, known as wafers. These wafers are cut into very thin sheets 200 micrometres thick. They are reprocessed and metallised into semi-conductors: the photovoltaic cells.



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Two types of photovoltaic cells: mono-crystalline or polycrystalline
Both these technologies have advantages. The mono-crystalline cells have better output whilst the polycrystalline cells cost less and last longer.

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Photovoltaic solar modules
The modules are panels made up of photovoltaic cells interlinked electrically. The module output depends on their specific technical features, the sunshine, their size, etc. Peak power is the term used for the maximum potential for electricity generated by a cell or photovoltaic panel. This is expressed in Watt-peak (Wp).

Did you know?
The peak power of a photovoltaic panel is in the order of 100 to 200 watts per square metre (i.e. an output of 10 to 15%), which gives a peak power of 50 to 250 Wp per panel.

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Structures
The structures are the components on which the photovoltaic modules sit. These structures differ according to how the solar panels are integrated (roof- or façade-mounted on a house, community buildings, industrial sites, car parks, etc.), architectural objectives and output goals.

The main options are:
- Structure flat on a roof (S-TE Linea)
- Structure built into a roof (S-TE Fixea)
- Shade screen structure (S-TE Protect)
- Ground-mounted A-frame structure (S-TE Solarland)
- Simplified Integrated Structure for large installations (S-TE Integra Max)
- Simplified Integrated Structure for small installations (S-TE Integra)
- Cement fibre structure (S-TE Fibra)
- Guard rail structure (S-TE Top Safe)
- Skylight structure (S-TE Lumex Design)
- Structures for flat roofs (S-TE EnerTop5)
- Impregnable structures (S-TE SunGuard)

For example, to create solar units (numerous panels lined up side by side directly on the ground), the modules are fixed on structures with type, height and slope calculated specifically in relation to the sunshine and which way the units are facing. The installation thus generates maximum output.

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Inverters
This is equipment which delivers voltages and alternating currents from a direct electrical energy source.

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Other components
Other components supplement the photovoltaic system based on its intended use: circuit breaker, production and consumption meter, regulator, monitor, etc.

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Specific features of generating photovoltaic energy on an isolated site

Any photovoltaic installation not connected to the electricity distribution network is known as an "off-grid" solution. There are then two techniques for accessing the electricity:

Power supply as the sun shines
The solar panel is connected directly to the receiver (specific low consumption electrical equipment) with no other components. The electrical power supplied to the receiver depends on the lighting power. These systems operate perfectly for water pumping.


Power supply with battery storage
Energy requirements very often do not match the hours of sunshine or require a regular current (general lighting or powering refrigerators, for example).
The photovoltaic solar system then has support batteries and accumulators used to store the power and restore it as and when it is needed.
It is also essential to use a regulator which protects the battery against overcharging or extensive discharging which could be detrimental to its service life.
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