Assessing the long-term stability of laser enhanced contact optimization (LECO) treated PERC cells in PV modules by extended indoor and outdoor durability tests

Abstract

It was previously shown that the Laser Enhanced Contact Optimization (LECO) Process is a promising boost for PERC and TOPCon cell manufacturing enhancement. In this contribution, a method is developed to assess the long-term stability of industrial LECO treated PERC cells in a module compound. Therefore, extended accelerated aging tests as well as outdoor measurements were performed on modules comprising LECO treated cells as well as untreated references. It is described, how data can be evaluated to separate typical, known aging and degradation effects from presumable LECO specific effects. The results of this work show that test modules comprising LECO treated cells did not show a different behavior in the accelerated aging or degradation compared to the reference. The same conclusion was found for thermal cycling and damp heat tests, both far in excess of IEC requirements, as well as in a sequential test sequence. In addition, their outdoor performance with local and integral measurements has been evaluated. We can conclude that for the tested PERC cells, aging and degradation effects appeared, but none of them could be attributed to the LECO process. Hence, improvements in the efficiency and/or yield on cell level due to LECO can be translated to the module or even system level considering typical aging and degradation behavior, independently of a prior LECO process.

Investigation of the Ag–Si Contact Characteristics of Boron Emitters for n‐Tunnel Oxide‐Passivated Contact Solar Cells Metallized by Laser‐Assisted Current Injection Treatment

“…[23,24] In addition, the results of the long-term stability evaluation, including extended thermal cycling and damp heat, were also within expectations. [25] Over the past few years, the working principle of LECO and the corresponding internal mechanism of Ag-Si contact based on PERC solar cells have been investigated. During the LECO process, a laser beam scans over the front side of a solar cell to locally excite charge carriers, and at the same time, a reverse bias voltage is applied on both sides of the solar cell to drive free carriers through metal-semiconductor contacts.…”