Novel in situ series connection for thin film photovoltaic modules

Abstract

The monolithically integrated series connection of single solar cell stripes into complete photovoltaic (PV) modules is one of the key advantages of thin film PV technologies. Instead of the well established laser scribing for series connection, this contribution focuses on a novel in situ series connection technology, without breaking the vacuum during module manufacturing, and without the need of costly laser-scribing equipment. Metallic wires or other filaments aligned along the slightly bent substrate, sequentially pattern the solar cell layers for implementing the monolithic series connection, simultaneously with the consecutive evaporation, plasma deposition, and sputtering of the semiconductor and contact layers. In addition to a proof of concept by flexible PV modules, this paper for the first time investigates wire-shading on rigid glass substrates and by multiple adjacent filaments. The results of these studies demonstrate that the in situ series connection is a promising candidate for competing with laser scribing, not only in roll-to-roll production of flexible PV modules, but also in batch or inline processing of standard large-area glass plates. Applying the novel in situ series connection to a laboratory-scale solar cell process, yields 40 cm 2 sized PV modules, consisting of ten single junction amorphous silicon n-i-p cells on a flexible polymer foil. The modules' total area efficiency of 3 % is close to the non-optimized efficiency of reference cells of 3.3 %. Wire-shading with wire diameters down to 50 µm proves successful, and thereby projects total interconnection losses F < 5 %, whereas the first experimental modules exhibit F = 15 %.

Thin-Film Silicon Solar Cells on Flexible Substrates

“…At the same time, this technology meets many problems in the case of its use to create panels on flexible polymer foils, resulting in an increase in the width of the incision, as well as problems associated with bypass surgery. Therefore, a technique of coupled elements using masks directly during different stages of deposition has been proposed [27,28].…”

“…Experiments have shown that in the case of nontextured PET foil for the substrate temperature of T d = 110°C the conversion efficiency was 9% [29]. Solar module with the area of 4×10 cm 2 that used a single-cell a-Si pin structure and formed on a polyethylene naphthalate (PEN) demonstrates a conversion efficiency of 3% [27].…”

Roll-to-Roll Front Contact Patterning by Wire Shading

“…The ISSC uses a wire frame which aligns parallel masking wires on the surface of rigid glass or flexible polymer foil substrates, and slightly shifts them between successive thin film depositions. The progress reported here is based on previous ISSC studies that used a static batch processing sequence [7,8]. This study analyses the dynamic in-situ wire shading during web coating of a 30 cm wide polymer foil with highly conductive Al-doped ZnO (ZnO:Al).…”

“…Further experimental details are given in ref. [6,7,8]. In addition to previous static experiments, this study examines dynamic roll-to-roll deposition and wire-shading of ZnO:Al in a cluster tool manufactured by MVSystems [9].…”

Optimization of the in situ series connection of amorphous silicon solar modules on glass and foil substrates

“…This contribution presents the alternative in situ series connection (ISSC) technology for thin film PV modules which avoids the need of breaking the vacuum during module manufacturing. For ISSC, masking wires aligned along the slightly bent substrate form the scribe lines simultaneously with layer deposition, and consecutive shifts of the masking wires implement the monolithic series connection of single cell stripes into completed PV modules 6, with no interruption of vacuum processing nor the need for extra equipment like costly laser and adjustment tools.…”