Influence of IR Soldering Profile on Industrial Silicon Heterojunction Solar Cells

Within this work, the influence of infrared (IR) light on bifacial n-type silicon heterojunction (SHJ) solar cells is investigated, with the focus on the industrial IR soldering process. The EL images and I-V parameters of industrial SHJ cells are compared before and after treatment with IR light. The temperature-time-profile of this thermal treatment is varied according to established soldering profiles used in silicon photovoltaics, reaching peak temperatures above 200 °C. As a result, a reliable process window for the interconnection process of SHJ solar cells is identified (max. 250 °C, max. 6 s), where thermal degradation is avoided and even slight improvements of the cell performance are observed (ΔVoc = +1.9 mV, ΔFF = +0.3 %, Δη = +0.1 %). Overall, these investigations demonstrate the feasibility of the established IR soldering process for SHJ solar cells during module integration and therefore extend the range of usable process options for a broad deployment of SHJ modules.