Review Article | Published:

Understanding the cell-to-module efficiency gap in Cu(In,Ga)(S,Se)2 photovoltaics scale-up

Nature Energyvolume 3pages466475 (2018) | Download Citation



Cu(In,Ga)(S,Se)2 (CIGS) solar cells show record efficiencies comparable to those of crystalline Si-based technologies. Their industrial module production costs are also comparable to those of Si photovoltaics in spite of their much lower production volume. However, the competitiveness of CIGS is compromised by the difference in performance between cell and module scales, known as the cell-to-module efficiency gap, which is significantly higher than in competing industrial photovoltaic technologies. In this Review, we quantify the main cell-to-module efficiency loss mechanisms and discuss the various strategies explored in academia and industry to reduce the efficiency gap: new transparent conductive oxides, hybrid modularization approaches and the use of wide-bandgap solar absorbers in the 1.4–1.5 eV range. To implement these strategies, research gaps relating to various device layers need to be filled.

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A.P.-R. acknowledges financial supports from the Spanish MINECO (Ministerio de Economía, Industria y Competitividad) under the WINCOST project (ENE2016-80788-C5-1-R), the European Regional Development Founds (ERDF, FEDER Programa Competitivitat de Catalunya 2007–2013) and the CERCA Programme from the Generalitat de Catalunya.

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    • Veronica Bermudez

    Present address: Solar Frontier KK, Atsugi Research Center, Atsugi-shi, Kanagawa, Japan


  1. EFESE, EDF R&D, Chatou, France

    • Veronica Bermudez
  2. Solar Energy Materials and Systems Group, Catalonia Institute for Energy Research (IREC), Barcelona, Spain

    • Alejandro Perez-Rodriguez
  3. IN2UB, Department of Electronic and Biomedical Engineering, University of Barcelona, Barcelona, Spain

    • Alejandro Perez-Rodriguez


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V.B. is currently working at the Atsugi Research Center of Solar Frontier K.K.

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Correspondence to Veronica Bermudez.

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