Evaluation of screen-printed metallization concepts for large-area BC-BJ solar cells

Abstract

In this study, we investigate a wire-based interconnection approach for back-contact back-junction (BC-BJ) solar cells with an edge length of 156 mm and screen-printed contact finger metallization. Every second contact finger is interrupted periodically, hence allowing for connecting contact fingers of each single polarity by wires without an additional insulation layer. By means of numerical simulations using the software Quokka, we show that contact finger interruptions up to 1 mm have no significant negative impact on the cell performance (Δ <; 0.1 %abs). Furthermore, adhesion tests of soldered cell interconnectors are carried out for different metallization concepts, aiming at finding suitable solder pad dimensions for 156 mm BC-BJ solar cells. Peel forces exceeding 1 N/mm are found for both investigated metallization concepts with i) screen-printed copper-based busbars with screen-printed insulation layer beneath, and ii) wire-based busbars without insulation layer

Emitter Patterning for Back-Contacted Si Heterojunction Solar Cells Using Laser Written Mask Layers for Etching and Self-Aligned Passivation (LEAP)

“…We speculate that the (p)a-Si:H emitter acting as an etch barrier for n-type cells also plays a role for etching and repassivation of the base contact area. Clearly, a cell design is preferable that uses only single line scribing, and uses an electrically isolated base contact bar, for example, by placing it on a separate level like in multilevel metallization schemes [23], [24]. Such a design is under development.…”