Periodic Reporting for period 2 - ESPResSo (Efficient Structures and Processes for Reliable Perovskite Solar Modules)
Reporting period: 2019-10-01 to 2021-09-30
The ESPResSo team targets alternative cost effective materials, novel cell concepts and architectures, and advanced processing know-how and equipment to overcome the current limitations of this technology. The consortium aims to bring the cell performance close to its theoretical limit by demonstrating cell efficiency of more than 24% (on 1cm²) and less than 10% degradation in cell efficiency following thermal stress at 85°C, 85% RH for over 1000h. Scale up activities utilising solution processed slot-die coating and laser processing will additionally deliver modules with more than 17% efficiency showing long-term (>20 years) reliable performance as deduced from IEC-compliant test conditions.
The ESPResSo team also envisions integrating modules in façade elements demonstrating a levelised cost of electricity (LCoE) of ≤ 0.05€/kWh. Prototyping advanced, arbitrary-shaped architectures with specific materials and process combinations will emphasize that new highly innovative applications like on flexible substrates or with high semi-transparency are well accessible in the mid- to longer-term with this very promising thin-film PV technology
Gradual development of large area deposition processes including blade and slot die coating for the perovskite photo-active layer as well as transport layers and electrode materials has been performed, resulting in full modules processed up to 10x10cm2, 20x20cm2 and even up to 35x35cm2. The former ones have achieved PCEs over 20%, the latter ones lag a bit behind still on the PCE value, with best obtained result of 13%.
Similarly, a variety of devices, both cells and mini-modules, have been evaluated under long term stress factors like temperature, light and humidity. With highly stable perovskite compositions and modifications on the transport layers, or use of metal-free electrodes, stable PCE beyond even 1000hrs under these conditions and especially at elevated temperature of 60 or 85C has been proven. In combination with appropriate edge sealing and/or lamination foils, several cell and module architectures have proven to sustain the lab testing conditions at 85C and 85% RH. However, combined stress testing including for example light soaking or continuous operation under maximum power point (MPP) conditions showed that the overall degradation mechanisms become much more complex and synergistic effects could occur. More effort is clearly needed to show its viability for > 20 years, and more specifically that new test protocols beyond currently used IEC standards are to be developed to make validation based on accelerated testing possible.
Operational lifetime is an important parameter in LCoE calculations, so clearly some assumptions needed to be made for that part of such calculations. Nevertheless, a full investigation of the perovskite module production process was made based on the developments within ESPResSO to fabricate the BIPV façade element containing eight 35 x 35 cm² modules. A value for the levelized cost of electricity of ≤ 0.05€/kWh could indeed be extracted from this study when this PV system would be operating in locations in Southern Europe. This analysis has not only set the boundary conditions for the minimal efficiency and operational lifetime to reach this cost target, but also on what process throughput, module sizes, cost distribution of materials and production etc should be considered.
Especially extending this analysis with a prospective view how the environmental product footprint could impact the European energy mix in coming decades was shown to be very fruitful. This analysis emphasized that perovskite PV technology could have a substantial effect on reducing the CO2 footprint of the European energy mix when deployment would occur in the timeframe of 2030-2040, with high emphasis on BIPV application.
The detailed life cycle and toxicity analysis, eco-footprint as well as cost calculations are hardly reported in literature up to the level anticipated in this project. The building integration demonstrator as well-developed use case is also a result not yet found back in literature.
Besides the fabrication and installation of this BIPV facade element, several other prototypes have been realized.
The OSI (One-step-interconnect) process was successfully completed also on substrate sizes of 35x35cm2 and thus has shown its potential as alternative interconnection technology next to the conventional P1-P2-P3 monolithic interconnection. Moreover, this process substantially alters the general module process flow enabling high customization of module layouts since the interconnection process is essentially decoupled from the layer deposition steps.
Using inkjet printing technology has resulted in effectively arbitrary shaped modules, like leaf- or hexagonal-shaped ones. Moreover, it was shown on plastic substrates and thus resulting in flexible modules.
Semi-transparent modules were used to realize tandem prototypes, in combination with cSi bottom cells. It was demonstrated that this combination outperforms the stand-alone efficiency of either the cSi cell or the perovskite module.
With this progress, the project substantially reduces the technological risks and thus de-risking future investments in a broad set of activities like building integration photovoltaics, but also flexible, customized and even tandem applications.
Covering also the life cycle and ecological aspects, the project enables substantial reduction of environmental impact, by using more environmentally friendly materials, minimizing material usage and by significantly extending the module lifetime overall a higher ratio of energy generated over energy used in production.
With several SMEs as partner in the consortium, the project collaboration enables them to build jointly a future technology base in Europe, ranging from materials, tools, thin-film modules up to final application products.
As such the results obtained will have a positive impact on CO2 reduction - supporting the ambitious European goals -, novel employment in renewable energy activities, and thus contributing to solving the global climate and energy challenges