Focus on solar energy – Discovery, operation and technologies

17/04/2019 Focus on

How does photovoltaics work?

Solar energy, an inexhaustible and abundant source of energy at the Earth’s surface. Throughout the world, the development of photovoltaic technologies enable us to exploit this source of energy immediately and at no cost. But how can we transform solar energy into electric current and what are the existing photovoltaic technologies which are able to achieve this?

The photovoltaic effect: how do we explain this phenomenon?

Solar energy is produced by light and heat particles called “photons”. When the photons collide with the surface of cells, they cause electrons to move, generating an electric current. The photovoltaic effect is therefore the name we give to the principle of converting light into electricity.

Photovoltaic system

This phenomenon can be reproduced using various solar technologies. Three types of technology co-exist: they take the form of either a rigid or a flexible photovoltaic panel, or of a flexible, light and semi-transparent solar film. Made up of an assembly of cells, these panels and photovoltaic films contain semi-conductive materials capable of transporting the electric current generated thanks to the photovoltaic effect.

Did you know?

In 1839 the French physicist Antoine Becquerel was the first person to discover the photovoltaic effect. This phenomenon remained an unexploited laboratory curiosity until American researchers finally developed the first photovoltaic cell in 1954.

What are the major differences between the different photovoltaic technologies?

There are many types of photovoltaic cells, depending on the material they are made of:

  • Monocristalline or polycristalline cells are prepared from a block of silicon. In order to be exploited, the block must undergo a lengthy transformation process involving considerable demands in terms of energy;
  • Amorphous silicon cells are different from the previous cells as the quantity of silicon required is much lower. These cells are made by only depositing a fine layer of silicon on the substrate;
  • Other cells in a thin layer also exist, made from various materials such as copper, indium, selenium and gallium. These materials are available in limited quantities and some are even becoming more and more rare due to human exploitation;
  • Finally, a new generation of thin-layer cells is gradually appearing on the market. They contain no traces of silicon: this mineral is replaced by organic polymers, hence the name “organic photovoltaic technology” (OPV).

Did you know?

Currently, over 90% of photovoltaic installations installed worldwide contain silicon. This hard mineral present in sedimentary rocks such as sand or sandstone is heated up to temperatures in excess of 3,000 °C and must undergo major physical and chemical treatment before becoming exploitable.

Yet the cost in terms of energy and the cost to the environment can now be minimized using photovoltaic technology of organic origin (OPV). The French industrial group ARMOR has decided to develop and produce only this type of technology.

OPV technology and its advantages

OPV technology comes from organic chemistry. The photovoltaic cells are made from a soluble formulation coated in an extremely fine layer onto a thin film. And the proof of this is that the thickness of the film can be measured in nanometers! This new technology therefore requires a very small quantity of raw materials during production, and its low-energy manufacturing process leaves a very low carbon footprint. The low demand on and preservation of natural resources are two of the major benefits of organic photovoltaics in terms of the environment, in addition to the technical advantages.

Solar Energy definition

ASCA®, an innovative and ingenious technology

The ASCA® organic photovoltaic film designed and produced by ARMOR is a revolutionary technology that offers new possibilities to exploit solar energy in a different way.

A unique formulation, produced in France

With a network of strategic partners, teams of researchers, engineers and technicians, who are continually designing and improving ASCA® technology, have developed photovoltaic cells from a formulation without equivalent anywhere in the world. They are solely composed of soluble polymers and raw materials that are neither toxic nor carcinogenic. ARMOR is committed to bringing an eco-responsible photovoltaic technology to the market. The ASCA® photovoltaic films are therefore produced using a coating process that deposits layers using a “slot-dye” coating process. This roll-to-roll manufacturing process selected by ARMOR to produce the ASCA® films is decidedly low-carbon. The process is very low in energy consumption unlike other methods based, for example, on vacuum evaporation. Consequently, its energy payback time (EPBT) is just 3 months, around 10 times faster than the other photovoltaic technologies.

A unique production capacity

ASCA® is produced by the same coating process used for coating thermal transfer ribbons – another area of industrial expertise in which ARMOR is fully proficient and is the global market leader. With this roll-to-roll wet-process mode of production, the extraordinary throughput of inked film production (800 meters per minute with a width of one meter) enables the French group to supply very high volumes. One million m² per year of 600mm-wide ASCA® photovoltaic film can be produced at ARMOR’s Industrial Expertise Centre, near Nantes.

Damien HAU - Innovation & Industrial R&D Manager at ARMOR

The expert’s view: Damien Hau, Innovation & Industrial R&D Manager at ARMOR

“Since 2010, our activities dedicated to the design and production of the ASCA® photovoltaic film have evolved significantly. Our personnel specializing in formulation, process, encapsulation and characterization has doubled in size in just 4 years, now making up a 40-strong team. We have invested 60 million euros in our production line in order to quickly meet industrial demand, providing a reliable solution able to cover all market requirements with a minimum lead time.

Between 2011 and 2018, the PCE rose from 10 Wc/m2 to 45 Wp/m2. The dimensions of the modules have also considerably increased. At the start our modules measured 4cm in width and 5cm in length, whereas now we are able to produce modules 60cm wide and 6m long. Furthermore, by assembling these “super modules”, we can offer customers much bigger dimensions: widths of 2.50m and lengths able to reach several tens of meters.

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