According to the International Technology Roadmap for Photovoltaics, passivated emitter and rear solar cells dominate the market in 2021 of up to 80% and are forecast to remain state of the art at least for the next 5 years. Within the production process of solar cells, it is typical to have cells with lower efficiency grades due to variations in manufacturing processes or material defects. Reprocessing such solar cells could save cost due to increased production yield and simultaneously reduced cost for recycling of unusable/unsellable low‐efficiency cells. Herein, the impact of the laser‐enhanced contact optimization (LECO) process on the power output and reliability of solar modules using commercial off‐spec cells of different manufacturers is analyzed. LECO is a downstream process for optimizing metal−semiconductor contacts on finished solar cells. The treatment leads to a significant economic gain due to enhanced cell efficiency (Wp ↑, therefore manufacturing cost per Wp ↓) even of already good solar cells. Herein, the first evaluation of the impact of the LECO process on the cell output power on an industrial scale (>1000 cells) and on module reliability is presented. The results for common short‐term effects like light‐induced degradation and light‐ and elevated temperature‐induced degradation are within expected limits and the durability against, for example, potential‐induced degradation is not changed due to the LECO process. The results further show that cell sorting is crucial for a reliable module and to avoid outliers in terms of unexpected degradation and recovery phenomena of individual cells.

This article presents a successful laser-powered cofiring process for highly efficient Si solar cells as a more compact and energy-efficient alternative to the conventional firing process in an infrared (IR) lamp-powered heat chamber. The best cell group reaches with laser firing only 0.1% abs lower cell efficiency compared to the best group with conventional firing, demonstrating the industrial potential of this laser firing technology. Adding the laser enhanced contact optimization (LECO) process after firing improves the cell efficiency for laser firing to the level of conventional firing, demonstrating the potential of the combination of the laser firing and the LECO process.

A technique to improve contacts of solar cells laser enhanced contact optimization (LECO) has been studied in terms of micro scale contact formation at industrial PERC solar cells. High-resolution diagnostics by focused ion beam techniques and scanning electron and transmission electron microscopy indicate the LECO-induced formation of microscopic contacts at the buried interface between the screen-printed silver finger and the silicon wafer. A large quantity of these micro contacts where found exclusively for LECO processed cells. Target preparation and threedimension cross-section investigation reveal an interdiffusion of the Ag and Si material as the underlying root cause for improved local contact resistivity. We propose a descriptive model for local ohmic contact formation maintaining surface passivation.

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