The main objective of this project is to create technological prerequisites for a drastic reduction in the per Watt manufacturing cost of amorphous silicon thin film PV modules. The cost reduction is achieved principally by developing industrially applicable solar cell and panel manufacturing processes for significantly higher module conversion efficiency and power. The main development area is the improvement of the quality and stability of the amorphous silicon thin film structure, but also the problem of geometric losses in the patterning of the thin films for finalized panels will be addressed.
The approach that has been adopted for the project is to develop tandem (dual junction) structures utilizing the possibility for bandgap tailoring in a-Si materials by producing a-SiGe alloys. Thus, spectrum splitting is utilized by having two different junctions absorbing different portions of the solar spectrum.
During the course of the project, each layer in the tandem structure is optimized for reaching high efficiency. This includes optimizing the light transmission in microcrystalline doped n- and p-layers, the current matching in the two junctions as well as optimizing the performance of the tunnel recombination junction between the two p-i-n structures. The optical and electrical parameters of individual layers will be determined from real samples and will then be used as input for computer device modelling to determine the optimized cell structure.
For transfer of results from laboratory into production the project relies on the complementarity of the partnership. Laboratory results and processes can be experimented in a pilot scale laboratory on large substrates before they will be tested in real production environment.
EXPECTED ACHIEVEMENTS AND EXPLOITATION
Manufacturing cost is the principal issue in the development of industrial PV technology. Presently the direct manufacturing cost (materials and direct labor cost) in Europe of industrial single junction a-Si modules with approximately 5% active area stable conversion efficiency is around 2.4 ECU/Wp.
For 1'x1' tandem panels manufactured with an industrial scale single chamber deposition system the goal for the development is to achieve a stable power of 6 W, corresponding to around 8 % active area efficiency. For more advanced laboratory tandem cells utilizing novel material and cell concepts the goal is to develop a manufacturing process for stabilized 10 % efficient cells. The transfer of these results into manufacturing without significant improvement in the manufacturing cost will reduce the direct manufacturing cost first to 1.6 ECU/Wp (panel level goal) and further to 1.2 ECU/Wp (cell level goal).
Funding SchemeCSC - Cost-sharing contracts
2600 GA Delft
3584 CC Utrecht