Light and durable: Composite structures for building-integrated photovoltaic modules

In several countries, building-integrated photovoltaics solutions could prospectively contribute to the growth of total installed photovoltaic (PV) capacity as they enable electricity production with minimal impact on free land. However, in some circumstances, the relatively high weight (>= 15kg/m(2)) of existing glass/glass building-integrated photovoltaics modules may constitute a barrier to the diffusion of PV in the built environment. With the aim of limiting the weight while preserving excellent mechanical stability and durability properties, we propose a new design for lightweight crystalline-silicon (c-Si) PV modules in which the conventional polymer backsheet (or glass) is replaced by a composite sandwich structure, and the frontsheet by a transparent polymer foil. Since sandwich structures are generally realized using epoxy as a gluing material, requiring long processing times, we further investigate (1) the possibility of using standard polymers used in the solar industry as alternative adhesives in the sandwich and (2) the possibility to considerably simplify manufacturing, using conventional lamination processes. Mini-modules are produced, characterized, and submitted to accelerated aging tests (thermal cycling and damp-heat) to assess the stability of the product against environmental degradation. We show that, by using the reference epoxy adhesive, it is possible to manufacture a lightweight (similar to 5 kg/m(2)) mini-module in a 2-step process, which successfully passes a selection of industry qualification tests, including thermal cycling, damp-heat, and hail test. We further show that, by replacing epoxy by a PV adhesive, we are able to considerably simplify the manufacturing process, while preserving excellent mechanical and durability properties.