Technology

Overview

Flisom solar modules are manufactured using a roll-to-roll deposition process to produce continuous high quality at low cost.
Flisom's key technology lies in the deposition of the CIGS (Cu(In,Ga)Se2) semiconductor compound. CIGS absorbs light and releases electrons.

Solar modules

A solar module is essentially an assembly of electrically interconnected solar cells and possibly other electrical components such as diodes and electrical wires or busbars. Depending on how the solar cells are interconnected within the solar module will enable it to produce more electrical current or more electrical voltage.
Components such as solar cells or diodes can be manufactured by depositing successive layers of material onto a sheet substrate such as various plastic sheets. The most important material, the so-called absorber, is what will convert light into electricity. The absorber compound used by Flisom is CIGS: copper (Cu), indium (In), gallium (Ga), and selenium (Se).

Roll-to-roll (R2R) manufacturing process

The roll-to-roll manufacturing process developed by Flisom enables the monolithical production of solar modules. That is, complex patterns of solar cells and other components can be designed and interconnected on a single sheet of plastic without having to add external hardware components. This is what is called monolithic interconnection. It is possible thanks to a sequence of depositions of material layers followed by laser scribings P1, P2, and P3 that delineate components after each layer is deposited.

The roll-to-roll process comprises the following sequence of material deposition and laser scribing steps:

1. A very thin foil, or web, of polyimide is progressively unrolled inside a vacuum chamber
2. A metallic layer is sputtered onto the web so as to create the back-contact of the solar cells
3. P1 scribe. The coated web exits the vacuum chamber and passes over a laser that scribes lines into the metallic layer to delineate individual solar cell back-contacts
4. The web enters a second vacuum chamber where the four elements of CIGS: copper (Cu), indium (In), gallium (Ga), and selenium (Se) of the semiconducting absorber layer are deposited
5. A transparent buffer layer is then deposited onto the CIGS layer so as to form a semiconducting p-n junction
6. P2 scribe. A laser scribes lines that delineate individual solar cell semiconductor components
7. The web enters another vacuum chamber where the front-contact layer is sputtered with transparent conductive oxide (TCO)
8. P3 scribe. A laser scribes lines that delineate components on the front-contact layer, thereby creating the monolithically interconnected solar cells that constitute a solar module
9. The final stage includes the application of electrical front contact grids, electrical busbars, protective lamination, and final roll-up for easy transportation and future deployment

Quality control

During the roll-to-roll production process the quality of deposition can be monitored non-invasively at various stages. The final modules are also tested under standardized lighting sources dedicated to solar technologies.

Some samples are also collected for invasive investigation, for example using scanning electron microscopy.