Durable Bonding of Lightweight Crystalline Silicon PV Modules

Lightweight semi-flexible crystalline silicon photovoltaic modules have been introduced in the market for several years and provide an appealing possible alternative to conventional modules. In particular they are well suited for flat industrial or commercial roofs with limited load bearing capacity. An appropriate method to install such lightweight modules is to bond them to the roof structures using a suitable adhesive. This bonding approach actually needs special attention and care because the joints will undergo frequent high loads while being exposed to all possible weather conditions for many years. We introduce the use of silicone structural adhesives in this application, leveraging the large and long experience with creating durable structural bonds in the field of structural glazing for facades. The right joint dimensions are calculated taking into account wind load and design strength of the adhesive. Adhesion is tested not only in the as-bonded state, but also after stringent accelerated aging tests (long-term immersion in water, UV exposure, damp heat treatment, thermal cycling), which is a mix of tests developed for structural glazing and for the photovoltaic industry. We show that strong and durable adhesion can be reached.