With a growing global focus on "green energy", companies are racing to develop higher efficiency and lower cost solar cells for various applications. We were asked to provide several materials testing systems to assist in the evaluation of the mechanical performance of thin films and substrates used in the manufacture of photovoltaic cells, also known as solar cells. Solar cells are developed and manufactured by numerous companies globally, each looking to optimize the energy output from the cell, while maintaining a high quality and reliability, and minimizing the cost of these devices. The International Electrotechnical Commission (IEC) is the world’s leading organization that prepares and publishes International Standards for all electrical, electronic and related technologies — collectively known as electrotechnology.
These companies must obtain the design qualification and type approval according to IEC 61646: "Thin-Film Terrestrial Photovoltaic (PV) Modules - Design Qualification and Type Approval" and/or IEC 61215: "Crystalline Silicon Terrestrial Photovoltaic (PV) Modules - Design Qualification and Type Approval". The standard mechanical load test determines the ability of the module to withstand a wind pressure of 130 km per hour. A load is gradually applied to the front and back surface, in turn, to 2,400 Pa and maintained for 1 hour, then repeated for a total of three cycles.
Other Instron tests for PV modules include:
• Four-point bend testing of glass and stainless steel substrates to ensure the edge strength of these substrates. This test is used to ensure the substrate's rigidity is sufficient to guarantee a reliable, long-term electrical connection throughout the cells.
• A 90° peel adhesion test on various layers of thin films, also known as "stacks". This peel test confirms the quality of the adhesion between the layers and the adhesives used. It is important for companies to know the adhesion strength of these various film layers and which interface may contain the least amount of adhesion strength.
We recommend using a single column electromechanical testing system equipped with a 90° peel adhesion fixture, pneumatic side action grips and rubber coated grip faces for measuring the peel adhesion forces for these thin film stacks. Bluehill® 2 Software automates the adhesion force measurement and provides the operator with supreme confidence in the testing results. Our unique 90° peel fixture is designed with zero friction so all force measurements are a direct result of the film and adhesive. Since film strength is so important, many companies have used the single column machines with pneumatic grips for tensile testing of thin films to investigate film tensile strength performance.
In summary, electromechanical testing systems and accessories help manufacturers ensure compliance to the mechanical load testing outlined in IEC 61646 and other internal compnay standards. Your local Instron technical representative can assist you in properly configuring a testing system to meet your requirements.