Industrial high performance crystalline silicon solar cells and modules based on rear surface passivation technology

Stimulated by the extreme market conditions, the increase in performance and the reduction of manufacturing costs of standard crystalline silicon solar cells and modules have been quite significant in the last years. This progress was achieved mainly by process and material improvements avoiding additional process complexity. As todays cells are predominantly limited by optical and recombination losses at the rear surface, dielectric rear surface passivation represents an obvious approach to overcome the limitations. In recent years several concepts have been developed to implement dielectric rear side passivation into industrial-scale mass production. In this paper a short review is given about the evolution of dielectric rear side passivation technologies as well as on state-of-the-art cell and module results. Simple and cost effective cell and module designs utilizing standard as well as innovative manufacturing technologies are presented. Furthermore, it is shown that for all major steps multiple process options are available to further reduce the manufacturing costs. Using an optimized emitter and screen-printed metallization on commercially available 156 mm x 156 mm p-type Czochralski-grown crystalline silicon wafers best cell efficiencies of 19.9% without dielectric rear surface passivation and 21.0% with dielectric rear surface passivation are demonstrated. Replacing the screen-printed front contacts by electroplated nickel copper contacts record efficiencies of up to 21.3% are reached. By optimizing the module design and materials to reduce the resistive and optical losses, a peak module power of up to 306 W and 19.5% aperture area efficiency are achieved. (C) 2013 Elsevier B.V. All rights reserved.