The European project FLEXCELLENCE: Roll to roll technology for the production of high efficiency low cost thin film solar cells

The EU research project FLEXCELLENCE started on October 1st 2005 and is set to last during 3 years. FLEXCELLENCE aims at developing the equipment and the processes for cost-effective roll-to-roll production of high-efficiency thin-film modules, involving amorphous and microcrystalline silicon. Eight partners, with extended experience in complementary fields, are involved. Within the first year of the project, a hot wire chemical vapour deposition system (HW-CVD) has been built; and a roll-to-roll deposition system for microwave plasma enhanced chemical vapour deposition (MW-PECVD) has been further developed and put into operation. In the meantime, the very high frequency (VHF) PECVD pilot line at VHF-Technologies is being upgraded to allow higher throughput. Regarding the optimisation of the VHF-PECVD process, device grade quality microcrystalline silicon has been deposited on 30 cm x 30 cm at 2 nm/s and laboratory scale a-Si:H and microcrystalline-Si:H cells have been developed in a new double chamber system on plastic substrates. So far, these cells achieve a conversion efficiency of 6.2 % and 8.2 %, respectively. In addition, a 2D simulation program has shown that only 10 % total losses from a solar cell to a module are achievable on the flexible VHF-Technologies modules. Finally, a first cost calculation has demonstrated that production costs below 0.8 EUR/Wp should be reasonably achievable with single a-Si:H cells, and that an important part of this cost is for the encapsulation.