Mechanical Testing Photovoltaic or Solar Cells

With a growing global focus on green energy solutions, solar cells companies are racing to develop highly efficient and low cost solar cells for various applications. 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

Peel testing of stacks 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.

The challenge of testing to these standards are:

• Maintaining a 90° angle throughout the test
• Data rate used to capture peaks and troughs
• Eliminating slippage throughout the test

Instron solution:

• Maintaining a 90° angle throughout the test – The 90° peel fixture is able to maintain this angle by using a low force sliding table that is adjusted throughout the test.  The fixture consists of a bearing mounted table, which is linked to the test system via a cable and pulley, as well as anchored on the back by a dampening coil spring. As the crosshead is driven in the tensile direction, the cable pulls the table to maintain a constant 90° angle peel, and the coil spring keeps the table from reacting to inertia caused by load peaks and troughs. This fixture is adaptable for both single and dual column frames.   
• Data rate used to capture peaks and troughs – Instron’s 5900 series frames enables data capture of up to 2.5 kHz to ensure that all fast changing test events are captured.  Too low of a bandwidth may “dull” the system and lead to missed peaks and troughs, resulting in lower average strength values. 
• Eliminating slippage throughout the test – The advanced screw action grips employ a patented “quick-change” jaw face design which enables operators to easily change jaw faces to accommodate the needs of their materials.  Pneumatic grips can also be used to maintain consistent gripping pressure throughout the test.

It is important to review these standards in order to fully understand the test setup, procedure, and results requirements.