Performance of solar cells integrated with rigid and flexible building substrates under compression

Abstract

Renewable solar energy has been increasingly used due to its efficiency and cleanliness. Integrating solar cells directly to supporting structures can eliminate the mounting systems and reduce the cost. Once integrated, the strains of solar cells and supporting materials become the same. Therefore, it is necessary to study the strain effect on the solar cells. This study evaluates the performance of amorphous silicon solar cells (a-Si) when they are integrated with building substrates, such as roofs and exterior walls. Based on the materials used and the failure modes under compression, these building substrates can be generally categorized into two groups: rigid and flexible substrates, which are simulated using concrete/FRP-wrapped concrete, and thin FRP plate attached to rubber, respectively, in this study. Cylinders from different materials were fabricated and bonded with (a-Si) solar cells, and then tested under compression. During the test, the (a-Si) solar cells were illuminated using a projector to simulate the sun light. J-V characteristics curves were measured and Maximum Power Point (MPP) was calculated. It is observed that the performance of (a-Si) solar cells remained unchanged until failure for specimens with rigid substrates; and buckling of solar cells, including both local and global buckling, occurred for specimens with flexible substrate. It can be concluded that, while the strain has negligible effect on the performance of (a-Si) solar cells under pure compression because of their small deflections, it has a significant effect on performance of solar cells under buckling because of the change in the angle and effective area receiving the light, which in turn causes the decrease of the performance. The findings from this paper can be used as a guideline to choose solar cells for building applications.