Wednesday, 24 September
08:30–10:00 | 10:30–12:30

Welcome to our second preview of the EU PVSEC plenary talks, which we want to continue with a glance at those scheduled for Wednesday. This is the morning of plenary talks, as we are preparing for a total of nine presentations covering the topics of:

Si PV Manufacturing: Pushing the Limits of Performance (08:30)
Perovskite – Silicon Tandems: Towards Commercialization (10:30)
PV Stability in the Field (11:30)

Let’s start with the early morning talks, where we placed the latest information about Si-technology and its developments. We reflect the current market situation with our first keynote plenary which will be given by Guangtao Yang of Trina Solar, Changzhou, China. His talk, titled 'Silicon Surface and Interface Study for >27% Efficient SHJ Solar Cell' will give insights into the current company strategy towards ever higher efficiencies in mass production. To achieve such high efficiencies, the optimisation of surface morphology becomes an important parameter to study. Trina will report on an attempt to chemically polish the usual rear/front texturisation in order to flatten the pyramid surface. They find that adjusting the polishing parameters significantly impacts the wafer’s optical performance. The deposition of the amorphous Si layer to form the heterojunction leads to a better passivation quality, meaning a better Voc (of 752 mV). Moreover, it seems that the p-type a-Si:H crystallisation behaviour is improved on these partially polished surfaces. With fill factors reaching 87%, and optimisation of the front/rear polishing parameters, Trina will certainly report about their top efficiencies of slightly above 27% for a 200 cm² wafer.

What inevitably follows in this morning session is the spotlight on the European situation, and the presentations cover technology, manufacturing, and commercial strategies.

For the large European Project 'IBC4EU: European Back Contact Technology' Florian Buchholz of ISC Konstanz in Germany will report on the progress of this consortium, which involves 17 partners from across Europe. The aim of the project is nothing less than developing the most promising route for rapidly establishing gigawatt-scale production in Europe. What is at stake is the technology competitiveness of the IBC (Interdigitated Back Contact) in an entire value chain confronted with current and future mainstream HJT (heterojunction), TOPCon (tunnel oxide passivated contact) or PERC (Passivated Emitter and Rear Cell) technologies.
The focus is on the cost-effectiveness not only of production equipment but increasingly on eco-design elements such as minimisation of scarce raw materials and indium-free design. The presentation will bring you the latest material, solar cells, and module development results as well as a novelty: the comprehensive LCC (Life Cycle Costing). Also, it is certainly worthwhile to learn the consortium’s approach for an inclusive LCA (Life Cycle Assessment) taking into account local social factors and environmental impact of the processing steps, as it could give a commercial advantage in an increasingly environmentally and socially conscious Europe.

The next plenary presentation will be about the 3sun factory in Catania, Italy, a European flagship in PV manufacturing. As the title 'Challenges and Opportunities in Scaling HJT Manufacturing at GW Level in Europe – Navigating the Path to Large-Scale Solar Success' already suggests, Cosimo Gerardi, CTO of the 3sun Gigafactory will give us insight into the challenges of scaling bifacial HJT technology to a 3GW/year PV factory in Europe. But certainly, we will also be briefed on the opportunities offered by the strong partnership with ENEL Greenpower, and most of all the significant 'in-house' R&D efforts. In close collaboration with the manufacturing processes, 3sun R&D has successfully developed bifacial HJT (Heterojunction) technologies which are production-ready, and are recently also expanding their portfolio into the next generation using Perovskites as the top cell. 30% efficiency seems to be within reach at 3sun!

To conclude this plenary session, we will curiously listen to 'Business Model Optimization for European Solar PV: a Study on Costs and Commercial Strategies'. As it seems that currently PV manufacturing will not receive the same political attention and funding compared to chip foundries and battery manufacturing, it becomes essential to have a closer look at the business models which would make investment in European PV manufacturing economically viable. Philippe Macé and the experts from the renowned Becquerel Institute will present details of the innovative modelling of PV technology commercialisation, by not only considering the well-known manufacturing steps but also by including parameters like target market segments, the distribution channels and a tailored pricing strategy. In a nutshell, their model combines cost optimisation with business optimisation. The plenary presentation promises to give insights into the results and their data presentation, and we also expect the analysis applied to the European IBC4EU project (see 2nd talk of the session)

Now there might be a very short coffee break on this busy plenary morning, as the fully packed second plenary session must start in time. As a current frontrunner in worldwide R&D, Perovskite technology will be on stage for the next 60 minutes. Come in and listen immediately to the 'World-Record Industrial Tandem Solar Cells on M10 Wafer Size', a presentation given by Fabian Fertig of Hanwha Q CELLS, Bitterfeld-Wolfen in Germany. The spoiler is: 28.6% efficiency! But stay and listen to the ingredients of this achievement. Firstly, the high efficiency results from a perovskite-Si tandem topology on a 330 cm² wafer. Secondly, many adjustments on layer uniformity, thermal budgets and contact structures add up to significant improvements when assisted by big-data correlation and learning tools. For the rapid transfer and scaling into a production process, a pilot line is utilised, allowing also to fine-tune the parameters of the already industrial-scale Si bottom cell. We will probably be impressed to learn how close these achievements are to the industrial scale.

The next plenary talk is titled 'Outdoor Performance and Reliability of Perovskite-Silicon Tandems: Fifteen Months of Monitoring in the NEXUS Project', given by Jordi Veirman of EURAC Research, Bolzano, Italy. This is a European multi-partner project aiming to develop a stable, high-efficiency Si-perovskite tandem which shall also meet eco-design standards. The consortium exposed encapsulated perovskite-silicon tandems of 2cm x 2cm at four different sites in Europe, and monitored the relevant performance parameters. Interestingly, on one site, water running off the samples was also collected for an early estimation of lead-leaching. As this analysis is performed in real-time, they could also detect eventual correlation between lead-leaching and electrical failures. The authors promise to present at the plenary the results of the analysis of long-term degradation, and also the valuable data generation for their own long-term energy yield forecasting tool.

Back to the third plenary of the session, with a presentation on the progress in the estimation of the commercial parameters of Perovskite-Silicon tandems. Baljeet Singh Goraya from Fraunhofer ISE in Freiburg, Germany will talk about the 'Total Cost of Ownership, LCA and LCOE Analysis of Perovskite-Silicon Tandems Compared to Single Junction Crystalline Silicon PV Technologies'. Currently, there are many activities about the modelling of the commercialisation of Perovskite-Si Tandems, but this one combines the calculation of LCOE (levelised cost of electricity) with wider-ranging approach of LCA (Life Cycle Analysis) to arrive at well-substantiated TCO (Total Cost of Ownership) estimate for 4 different PV technology types: two c-Si based SJ technologies, and two 2-terminal (2-T) perovskite Silicon tandem technologies. All modelling considered a hypothetical cell and module factory with a minimum yearly production capacity of 5 GW. The TCO analysis results show an increase in PV module production costs ranging from 1% to 45% for the perovskite-silicon tandem technologies compared to the c-Si single junctions on a per watt-peak base. However, when extending the model to the LCOE assessment for residential use, it was found that the perovskite-SHJ based tandem provided the lowest LCOE compared to all other technology types, showing an LCOE advantage of 6.6% over the single junction TOPCon technology. When the consortium looked at the LCA of the different technologies, perovskite tandems have a lower global warming potential than SJs due to higher efficiency, but only if the system lifetimes match the 30 years of the SJs. So far, the results are only preliminary, we hope for confirmed results to be presented during the plenary talk.

In the third part of this Wednesday plenary, we feature two more presentations specialised on degradation and PV inspections. As UV-induced degradation of up to 5% is an issue in modern Si cells, you might want to take part in 'Understanding the Root Cause of UV-Induced Degradation in TOPCon and PERC Solar Cells'. The talk will be given by Muhammad Umair Khan of UNSW, Sydney, Australia, and the authors suspect and explain an increase in hydrogen concentration at the TOPCon front structure. More sophisticated measurements reveal an increase in interface defect density with rising UV doses. The corresponding increase of silicon dangling bonds explains the drop both in both V_oc and I_sc. The talk will also explain why the rear contact of the TOPCon cells does not contribute to the UV-induced degradation.

Finally, the last presentation in this session is titled 'Enhanced EL Drone Imaging. High Resolution Electroluminescence for Advanced PV Inspections' and Sergio Suarez of Enertis Applus in Madrid, Spain will present an innovative approach, utilising proprietary drones to overcome the limitations of current EL imaging techniques. What is new is the combination of both CMOS and InGaAs cameras in a single system, covering a wider spectral band and allowing much lower exposure times. This promises a substantial improvement in defect identification, in particular as the imaging analysis is assisted by AI. The presentation will certainly display good imaging examples, and possibly a video of a real field-inspection fly-by without hovering or stopping.

This concludes our 'Sneak Preview' of the Wednesday plenaries. We are sure you will find the programme as interesting as we do.

Next week, we will continue with our preview of the plenary session on Friday, covering the topic 'Flexibility and Sustainability'.