Italian prototype makes glass-free silicon solar modules flexible

A four-cell solar module sat on a curved support for 672 hours, bent to a 150 mm radius and operated continuously under short-circuit conditions. It retained 96.12% of its initial efficiency, according to Paola Jakuza and colleagues at the University of Padova and the Institute of Materials for Electronics and Magnetism of the Italian National Research Council, or IMEM-CNR.

The team’s prototype removes glass from a crystalline-silicon, or c-Si, solar module. Instead, commercial 150-μm interdigitated-back-contact cells — cells with their electrical contacts on the rear — were placed in a PET/EVA/c-Si/EVA/PET stack. PET is a flexible plastic layer; EVA is the encapsulating material around the cells. Together, the outer PET layers provide mechanical protection while allowing the module to bend.

The researchers used a commercial hot-roll laminator to emulate a roll-to-roll production process, joining the stack in a single atmospheric pass. They tested bare cells, single-cell modules and four-cell mini-modules connected in series. After lamination, efficiency fell by approximately 4.4% in relative terms. Jakuza said measurements pointed mainly to optical loss from reflection at the front PET surface, rather than electrically active cracks or damage caused by processing.

The mechanical results were mixed in a useful way. A single-cell module showed no cracks when bent to a radius of 95.4 mm, with efficiency declining by about 3.4%, mainly because illumination became uneven. The four-cell module retained 93% of its flat-state power output at a bending radius of 155 mm. The team translates those results into a recommended bending radius above 200 mm, along with bonding and thermal-management constraints.

So what changes in practice? A lighter, flexible silicon module could be considered for building-integrated photovoltaic applications where rigid glass panels are difficult to place, while retaining a mature cell technology rather than relying on newly manufactured cells. The evidence remains at prototype stage: the researchers plan anti-reflective coatings, solder-paste integration and longer thermal-cycling, repeated-bending and outdoor durability tests before the design’s reliability is clearer.