Investigating the shaping boundaries of flexible photovoltaics on doubly curved uncoated woven textile geometries

Abstract

The built environment faces the challenge of meeting the sustainable development goals of the Paris Agreement with regards to building emissions. One aspect of this challenge is the energy transition from fossil to more sustainable sources. A possible solution lies in the field of solar energy technology which, over the last decades, has become the main sustainable energy source globally. Various types of solar cells exist today, from large-scale solar parks to small strips of flexible organic photovoltaics, or OPV. In parallel, the field of tensile architecture provides answers to the materiality challenge of the same sustainable development goals. Tensile architecture is lightweight by nature, which reduces the material use. This reduction in turn limits the embodied carbon of the material.

The current body of knowledge regarding textile engineering shows a wide variety of different types of textiles in architecture. In parallel, the knowledge around the bending of semi-rigid elements such as the OPV strips supports their use in curved geometries. However, gaps remain relating to the use of uncoated textiles in tensile structures, as well as the non-adhesive integration of semi-rigid elements such as OPV strips.

Given the context, the main research question of this thesis was:
To what extent can an uncoated woven hybrid textile, using non-adhesively integrated solar cells, be applied in doubly curved tensile structures?

SUNTEX, a newly developed hybrid textile consisting of rPET yarns and slender OPV strips, defined the scope of this research. A number of design parameters was established to determine the largest possible surface area, or maximum coverage, of OPV strips on a hyperbolic parabola and a saddle surface between arches, or barrel vault. To this end, a two-step computational analysis, using the Easy and Rhino Grasshopper software packages was performed. The analysis tool was designed to be compatible with current, conventional design workflows.

Results from the research showed an OPV strip coverage on the hyperbolic parabola of 23%. This best case scenario was produced on a shape which was divided into 5 cutting pattern segments. The barrel vault supported a maximum of 30% of the total surface area. This coverage was achieved on a shape which was divided into 5 cutting pattern segments. These results are global optima, as either increasing or decreasing the numerical design parameters results in a reduction of coverage on both shapes.

The conclusion of this thesis is that SUNTEX can be applied on doubly curved surfaces with a coverage up to 30%, depending on the type of shape that is used in the design, as well as the right combination of design parameters. Within a design sequence, the iterative analysis method that was researched in this thesis should therefore be applied twice. Once at the early design stages, and once at the detailed design stage.
It is recommended that the design parameters are further explored to better understand their influence on the coverage on various shapes. Apart from that, the analysis method itself should be evaluated to reduce the run time, and improve of the accuracy of the results.