Title:	High Fill Factor CIGS Solar Modules by Evaporated Metal Grid: Numerical Simulation and Module Validation
Author(s):	S. Lin, H. Shan, D. Zhuang, R. Wächter, T. Repmann, T. Freund, N. Zancan
Keywords:	Metal Grid, CIGS Module, Numerical Simulation, Evaporation, P2 Busbar
Topic:	Perovskites, other Non-Silicon-Based Photovoltaics and Multi-Junction Devices
Subtopic:	CI(G)S, CdTe and Related Thin Film Solar Cells
Event:	36th European Photovoltaic Solar Energy Conference and Exhibition
Session:	3BV.1.62
Pages:	708 - 712
ISBN:	3-936338-60-4
Paper DOI:	10.4229/EUPVSEC20192019-3BV.1.62
Price:	0,00 EUR
Document(s):	paper, poster

Abstract/Summary:

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In this article, we focused on CIGS thin-film solar module structure optimization. Based on numerical simulation results by PVMOS software, we designed the structure of metal grid and chose the optimized parameters. By analyzing the loss, we deduced that P2 busbar would be helpful to reduce Ohmic heating effect in the module. The high definition P2 busbar is creatively added by a new method with E-Beam Al evaporation. Transmission-line-model (TLM) measurement reveals that the contact resistivity between AZO and evaporated metal grid is extremely low (<0.05m-cm2). Although a low contact resistivity seems to be quite beneficial for reducing serial resistance, therefore increasing module fill factor. However, the simulation results show that such low contact resistivity could strongly enhance the shunting effect when shunting defects are under the metal grid fingers. By removing of these local shunting defects manually, the final finger-shunting-free modules show high fill factors. The modules with metal grid fingers only and with P2 busbars + grid fingers on 100100 mm2 substrates both show high fill factors > 77% even on 7 mm width sub-cells with 25 / TCO. Compared with the reference modules composed of 4mm sub-cells, the metal grid and P2 busbar structure modules show increase not only in FF from 73.5 % to >77%, but also the active area ratio from 93.7% to 94.1% according to our design parameters. P2 busbars not only reduce the heating in finger/P2 contact area, but it could also better balance the loss in contact resistivity and in grid finger enhanced shunting. Metal grid with P2 busbar is a promising technology for future high performance thin-film solar modules according to the simulation results.