A woven fabric for interconnecting back‐contact solar cells

Abstract

This paper reports on a novel and highly innovative technology to interconnect back‐contact cells. First, a background section explains the currently developed interconnection technologies. Then, our novel concept is introduced: interconnection of the cells is achieved with a woven fabric, combining both conductive wires, needed for the interconnection, and insulating wires, crucial to avoid shunting between both polarities at the backside of the cell. Weaving also allows out‐of‐plane stress relief features. In the third section, we explain that our technology combines the advantages of multi‐wire interconnection such as low‐stress and reduced resistive losses with known and low‐cost materials of traditional module assembly. Additional to previous publications, we demonstrate that the technology can be tuned broadly in terms of costs and resistive losses using an optimized interconnection pattern. These resistive loss simulations are also validated with the measured additional resistance in IBC test samples. We also present a preliminary thermal cycling test with promising results. Finally, first functional demonstrators IBC cells are fabricated, disclosing the process flow and initial technology developments. These results clearly demonstrate the proof‐of‐concept of the woven interconnection fabric, and based on electrical characterization we provide suggestions for improvements. Copyright © 2016 John Wiley & Sons, Ltd.

Interconnection and lamination technologies towards ubiquitous integration of photovoltaics

“…In an updated version of the interconnect foils from, 21 by implementing a patented method, 22 we have now improved and extended reli- T A B L E 2 Multi-wire (MW) interconnection applied for opaque (blue and magenta) building-integrated PV (BIPV) applications: current-voltage (IV) performance (measurement error <2%). T A B L E 3 Multi-wire (MW) interconnection applied for semitransparent building-integrated PV (BIPV) applications: currentvoltage (IV) performance of reference 5BB and MW modules integrated into an insulated glazing unit (IGU) (measurement error <2%).…”

Three‐dimensional multi‐ribbon interconnection for back‐contact solar cells

“…An important factor, since the International Technology Roadmap for Photovoltaics predicts a simultaneous increase in world market share for bifacial cell production and back‐contact cell technologies, increasing the demand for bifacially compatible back‐contact interconnection methods 11 . Imec's woven interconnection attempts to overcome this, by using an interconnection foil of copper wires held in place by interwoven, continuous glass fibres 12 . This brings the advantage of reduced silver consumption and an increased power yield from the multi‐wire interconnection technologies for two‐side contacted cells 13 .…”

“…As a next innovation, we propose the three‐dimensional (3D) multi‐ribbon interconnection, which carries some advantages from the latter technology such as CTE compensation by single connection points and decreased material consumption due to a tapered design, while potentially lowering the production costs by simplifying the design and module fabrication process. We described in more detail how the tapered design can optimize the Cu consumption in a previous publication 12 . The open character of the weave allows interconnecting bifacially active, back‐contact cells.…”

“…A more in‐depth analysis of the progress and knowledge of the back‐contact interconnection technology is beyond the scope of this paper but can be found in previous publications. 12,13 …”

“…By interrupting the cell‐to‐cell ribbons on specific locations, the fabric gets a tapered design and one ribbon can be used for two opposite polarities, which can save on copper consumption. 12 …”