Flexcellence: Towards roll-to-roll mass-production of low cost thin film silicon solar cells

The authors report on the mid-term results obtained in the frame of the European FLEXCELLENCE project which aims at developing the equipment and the processes for cost-effective roll-to-roll production of high- efficiency thin-film modules, based on amorphous (a-Si:H) and microcrystalline silicon. Eight partners, with extended experience in complementary fields ranging from device simulation to machinery development, are involved. During this first part of the project several milestones were achieved: Setting-up and operation of roll-to-roll systems for deposition of solar cells by micro-wave PECVD, hot-wire and VHF PECVD; fabrication of high quality nanotextured substrates both on plastic foils and on metal foils with insulation; achievement of high efficiency devices on textured plastic substrates with initial efficiencies of 8.8%, 8.6% and 10.9% for amorphous silicon, microcrystalline and tandem micromorph cells, respectively; improvement in interconnection technologies, module encapsulation and reliability; demonstration of the possibility to reach ultra-low cost (< 0.6 EUR/Wp) if high efficiency micromorph concepts can be realised in production; successful integration by one of the partners of new high-throughput VHF- electrodes and move to module mass production. Thanks to the collaborative nature of the project, important steps towards the goal of mass-production of high efficiency thin film Si modules have consequently been realised.