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Understanding Thermal Expansion in Solar Modules

When it comes to designing solar modules, it is crucial to consider the impact of temperature on the materials used. One significant effect to take into account is thermal expansion, which refers to the tendency of materials to change in shape, volume, and length in response to temperature variations.

Stress Relief Loops: Minimizing Expansion-Related Stress

One method used to address the expansion of materials in solar modules is the incorporation of stress relief loops. These loops help to accommodate the expansion that occurs between cells when the temperature increases.

The spacing between cells in a solar module is designed to allow for an increase in distance, denoted by δ. This increase is determined by factors such as the expansion coefficients of the materials used (such as glass and the cell), the width of the cell, and the center-to-center distance between cells.

Interconnections between cells are often looped to minimize cyclic stress that can result from temperature-induced expansion. By using a larger number of thinner wires for interconnection, the stress at each connection point is reduced, lowering the risk of failure.

Double Interconnects and Modern Solutions

To further mitigate the risk of fatigue failure due to stress, double interconnects have been introduced in solar module design. Over time, the number of interconnects has increased significantly, from just 2 to as many as 12 or more in modern cells.

Modern solar cells utilize multiple interconnects to distribute stress more evenly and reduce the likelihood of failure at any single connection point. This approach helps to enhance the overall durability and performance of solar modules.

Addressing Temperature-Related Cyclic Stress

In addition to interconnect stresses, solar module interfaces are also susceptible to cyclic stress related to temperature fluctuations. This cyclic stress can eventually lead to delamination, highlighting the importance of considering not only thermal expansion but also other temperature-related factors in solar module design.

By understanding and effectively managing the effects of thermal expansion and temperature-related stress, designers and manufacturers can develop more resilient and reliable solar modules for a sustainable energy future.

Source: MDPI