Use of digital image correlation technique to determine thermomechanical deformations in photovoltaic laminates

Measurements and accuracy

authored by: Ulrich Eitner, Marc Köntges, Rolf Brendel
Abstract: An experimental technique to measure the deformation of solar cells in transparent PV modules is presented. This method uses the digital image correlation technique with a stereo camera system. Deformations resulting from thermal loading, where rather small deformations occur compared to tensile or bending experiments, are measured by viewing through the window of a climate chamber. We apply this method to measure the thermomechanical deformation of the gap between two crystalline silicon solar cells by viewing through the transparent back sheet of the laminate. Two PV laminates are prepared, each with three crystalline silicon solar cells that are embedded in transparent polymer sheets on a glass substrate. The first laminate (A) contains non-interconnected cells while the second laminate consists of a standard-interconnected cell string (B). We find the gap between two solar cells to deform 66.3±2 μm between 79.6 and -17.3 °C (laminate A) and 66.4±2 μm (laminate B) between 84.4 and -39.1 °C. We determine an accuracy of 1 μm in displacement for the gap experiment by measuring free expansion of a copper strip and averaging displacement values over regions with homogeneous deformation. Furthermore, the relative error contribution in strain due to the optical influence of the layers on top of the object surface is less than 1×10^-6 for one camera. This is proven by a geometrical consideration.
External Organisation(s): Institute for Solar Energy Research (ISFH)
Type: Article
Journal: Solar Energy Materials and Solar Cells
Volume: 94
Pages: 1346-1351
No. of pages: 6
ISSN: 0927-0248
Publication date: 08.2010
Publication status: Published
Peer reviewed: Yes
ASJC Scopus subject areas: Electronic, Optical and Magnetic Materials, Renewable Energy, Sustainability and the Environment, Surfaces, Coatings and Films
Sustainable Development Goals: SDG 7 - Affordable and Clean Energy
Electronic version(s): https://doi.org/10.1016/j.solmat.2010.03.028 (Access: Closed)