Midsummer AB of Järfälla, Sweden, a supplier of equipment for manufacturing flexible copper indium gallium diselenide (CIGS) thin-film solar cells, has increased the energy conversion efficiency of its cells from 15% to 16.2% aperture area for the full 156mm × 156mm solar cell.
Picture: Midsummer’s flexible CIGS thin-film solar cells.
The solar cell was manufactured in a regular production run and the process is already implemented in the production line. “Considering that the solar cell is made on stainless steel, contains no cadmium and that the production process is an all-dry, all-vacuum process where all layers (including the buffer layer) are deposited by sputtering, this achievement by our engineers is truly impressive,” reckons CEO Sven Lindström.
Inexpensive lightweight flexible modules
With Midsummer’s production system, the solar cells are manufactured individually and then strung together into modules, as with crystalline solar cells. This way, lightweight flexible modules can easily be made in any size and shape, says the firm.
A dry, all-vacuum process has less stringent requirements for cleanrooms, says Midsummer. In addition, avoiding cadmium in the manufacturing process is desirable for the sake of the production staff and also makes it easier to start low-cost manufacturing of CIGS solar cells.
Market shifts towards rooftop installations
“The global solar cell market is facing a paradigm shift,” believes Lindström. “Fewer large solar energy parks are being built in Europe. Instead, focus is moving to installations on large buildings in cities. Lightweight and flexible thin-film solar cells are ideal for this use,” he notes. “It is economically and environmentally more beneficial to use solar energy locally, where it is produced.”
