Final Report Summary - SE-POWERFOIL (Roll-to-roll manufacturing technology for high efficient multi-junction thin film silicon flexible photovoltaic modules)
The SE-POWERFOIL project aimed to develop highly efficient, flexible thin film silicon photovoltaic (PV) modules, which were produced in a roll-to-roll process on metal foil, using innovative, batch type laboratory deposition processes. The principal objective was to achieve higher efficiency and longer operational life with reduced manufacturing costs in comparison to commercial alternatives. Therefore, it was necessary to propose and evaluate technical and economic innovations regarding both the device and the manufacturing process.
The applied methodologies examined numerous technology components, such as raw materials, the thickness and efficiency of the film layers and the potential for control and optimisation of the light scattering and reflecting electrode properties. Significant technical improvements were made and increased efficiency was reached; nevertheless, further improvement of the manufacturing robustness was necessary.
Cells and modules were fabricated by hydrogenated polymorphous silicone using the temporary foil substrate concept. A design that produced and analysed individual cells rather than modules was selected in order to achieve higher cell efficiencies. In addition, thin film silicon tandem modules were fabricated on a laboratory scale by integrating all optimised building blocks. The initial goal of 12 % stable efficiency was not achieved, even though a maximum efficiency of approximately 11 % was reached. Future research should focus on the strong degradation of the devices, as well as on the integration of novel, improved functional layers.
In parallel, new materials were investigated for optical layers like windows, intermediate reflectors and black reflectors. Relevant efforts resulted in solar cells of noticeable performance. Deposition rates were monitored in a state of the art multi-chamber deposition system. The elaborated experiments facilitated the development of an innovative, adapted technology.
Moreover, the high efficiency potential of the hot wire chemical vapour deposition (HWCVD) technique was demonstrated on a laboratory scale. The quality of solar cells with hot-wire deposited absorber layers was essentially unaffected by changes in the superstrate type. The applied technique increased as well the efficiency of tandem cells. Finally, the micromorph tandem module made by HWCVD was very stable against light soaking.
Flexible PV modules represented an economically viable alternative to rigid thin film PV modules in terms of manufacturing, installation and integration costs. Fast deposition technologies were identified as an additional critical parameter for low cost applications, and HWCVD appeared as a promising option for mass production. A new coater head design enabling fast deposition was successfully developed as part of SE-POWERFOIL and increased understanding of the CVD system operation and design. In addition, similar options were investigated for the active silicon layer.
The modules' lifetime affected the kWh production cost as directly as their efficiency. As a result, barrier encapsulation layers were applied both at the back and front side of the cells. Research on those layers was undertaken in parallel to the project. Evaluation of the proposals was based on performance monitoring both in the field and with the aid of standard accelerated lifetime tests.
SE-POWERFOIL was highly successful and most of its technical and scientific objectives were reached. Even though the developed product was not commercially exploitable at the end of the project lifetime, the observed efficiencies and the competitive costs were promising in terms of the potential for future technology exploitation.
The applied methodologies examined numerous technology components, such as raw materials, the thickness and efficiency of the film layers and the potential for control and optimisation of the light scattering and reflecting electrode properties. Significant technical improvements were made and increased efficiency was reached; nevertheless, further improvement of the manufacturing robustness was necessary.
Cells and modules were fabricated by hydrogenated polymorphous silicone using the temporary foil substrate concept. A design that produced and analysed individual cells rather than modules was selected in order to achieve higher cell efficiencies. In addition, thin film silicon tandem modules were fabricated on a laboratory scale by integrating all optimised building blocks. The initial goal of 12 % stable efficiency was not achieved, even though a maximum efficiency of approximately 11 % was reached. Future research should focus on the strong degradation of the devices, as well as on the integration of novel, improved functional layers.
In parallel, new materials were investigated for optical layers like windows, intermediate reflectors and black reflectors. Relevant efforts resulted in solar cells of noticeable performance. Deposition rates were monitored in a state of the art multi-chamber deposition system. The elaborated experiments facilitated the development of an innovative, adapted technology.
Moreover, the high efficiency potential of the hot wire chemical vapour deposition (HWCVD) technique was demonstrated on a laboratory scale. The quality of solar cells with hot-wire deposited absorber layers was essentially unaffected by changes in the superstrate type. The applied technique increased as well the efficiency of tandem cells. Finally, the micromorph tandem module made by HWCVD was very stable against light soaking.
Flexible PV modules represented an economically viable alternative to rigid thin film PV modules in terms of manufacturing, installation and integration costs. Fast deposition technologies were identified as an additional critical parameter for low cost applications, and HWCVD appeared as a promising option for mass production. A new coater head design enabling fast deposition was successfully developed as part of SE-POWERFOIL and increased understanding of the CVD system operation and design. In addition, similar options were investigated for the active silicon layer.
The modules' lifetime affected the kWh production cost as directly as their efficiency. As a result, barrier encapsulation layers were applied both at the back and front side of the cells. Research on those layers was undertaken in parallel to the project. Evaluation of the proposals was based on performance monitoring both in the field and with the aid of standard accelerated lifetime tests.
SE-POWERFOIL was highly successful and most of its technical and scientific objectives were reached. Even though the developed product was not commercially exploitable at the end of the project lifetime, the observed efficiencies and the competitive costs were promising in terms of the potential for future technology exploitation.
