Flexible modules offer benefits over traditional crystalline silicon rigid modules for flat rooftop applications. The longer thin film modules cover more area per module at a fraction of the weight. Additionally, flexible modules can be placed directly on the roof, eliminating the need for mounting racks, structural reinforcement and penetration. This design dramatically reduces installation material and labor costs. So despite, not quite reaching the efficiencies of wafer-based crystalline silicon cells per square inch, they can often offer better paybacks, or enable solar installations in places that can’t handle glass panels, such as light weight roofs, high wind areas, curved surfaces, etc.
The flexible design must have some backbone and be rigid enough to protect the PV cells from damage, the thin film technology can break if folded or bent at too sharp an angle. To support the thin film module foil can be laminated into the module construction. This allows the module the desired amount of flexibility but also provides enough rigidly to protect the photovoltaic cells, typically copper indium gallium selenide (CIGS), from mechanical damage.
Although foil adds structural support to flexible modules, there are other means to meet that requirement without the cost and material handling complexities of foil substrates. However, another issue with CIGS PV technology is its moisture sensitivity. Traditional rigid solar modules typically allow ~3g/m2 per day moisture transmission without affecting the module performance. Thin film modules, on the other hand, require a near 100% moisture barrier.
The foil laminate meets the requirements for moisture barrier and structural support, making it among the most advantageous substrates for flexible PV applications.