Photovoltaic integration in curved parts: Mechanical limits and key parameters from a theoretical point of view

Photovoltaic cells are produced as thin flat layers. They behave as a brittle and elastic material that fails at a given level of stress. Conforming cells into curved geometries will a priori induce both flexure and membrane stresses. In the present work, an analytical model is derived to predict both stress distributions and intensities in a mono-crystalline pseudo-square cell. Furthermore, a second model is derived to find the main stresses within fractions of cells. For conventional cell dimensions, solutions predict a transition from flexure to membrane dominated stresses for most conformations as curvature increases. As a consequence, near failure stresses are mainly determined by cells size and aspect ratio. In contrast, flexion is the main contribution in a small subset of the curvature space or for small curvatures. In the corresponding cases, stresses scale in proportion to cells thickness. As a consequence, cell size and/or shape is the main parameter to reduce internal stresses in most cases. In particular, the use of fractions of cells can substantially decrease membrane stresses and thus increase the maximum curvature. For instance, in a case study with M0 cells and curvature radii of a few meters, the highest predicted tensile stress is 45 MPa$$ \mathrm{MPa} $$. In such a case, the larger M12 format gives a prediction of 65MPa$$ 65\kern0.1em \mathrm{MPa} $$. In contrast, thirds of cells give predictions of 25 and 30MPa$$ 30\kern0.1em \mathrm{MPa} $$, respectively.