Area 1: Elisa Antolín, Universidad Politecnica de Madrid, Spain

Elisa Antolin is an associate professor at Instituto de Energía Solar, which is part of Universidad Politécnica de Madrid. Her research focuses on new materials and novel photovoltaic concepts, including ultrathin solar cells made of two-dimensional materials, three-terminal multijunction architectures and quantum dot devices.

Title: Ultrathin Solar Cells Based on Transition-Metal Dichalcogenides

Abstract: Ultrathin solar cells offer exciting opportunities for the expansion of photovoltaics beyond conventional installations. A technology of low-weight, low-cost, and possibly flexible or semitransparent devices could transform virtually any surface into a power generator, from facades to vehicle exteriors to wearables. In this talk I discuss the potential of transition-metal dichalcogenides, such as MoS2 and WSe2, as light absorbers to fabricate ultrathin photovoltaic devices. These materials are especially attractive for several reasons: their layered crystalline structure, which enables the isolation of very thin laminae with excellent electrical properties, their extremely high absorption coefficient, and the possibility to fabricate devices from solution by low-cost methods. The challenges of this emerging technology and our experimental progress are presented, with emphasis on the management of surface effects and the achievement of ohmic contacts and high open-circuit voltages. I will show a very simple 1D optical cavity design that enables the absorption of 90% of supra-band gap photons in a MoS2 absorber with thickness 10 nm. Due to the unique absorption properties of transition-metal dichalcogenides, semitransparent designs are also possible for power-generating windows that produce a color-neutral transmitted light spectrum even in combination with high opacity.

Area 2: Susanne Siebentritt, University of Luxembourg, Luxembourg

Susanne Siebentritt heads the laboratory for photovoltaics, which she established in 2007 at the University in Luxembourg. Her research focus is on chalcopyrite solar cells. She is interested in fundamental loss mechanisms and tandem cells.

Title: CIGS - From Bottom to Top

Abstract: Chalcopyrite solar cells based on Cu(In,Ga)(S,Se)2 show cell efficiencies of more 23% and module efficiencies of nearly 20%. They have a long history of installations, proving their stability. They can be made light weight and bendable. The material class offers a wide range of band gaps, which are suitable for single junctions, as well as for bottom and top cells in tandem applications.

Various new developments open the path to even higher efficiencies and more efficient production: alloying with Ag allows lower deposition temperatures, a passivated back contact enables thinner absorbers without backside compositional gradient, transparent back contacts permit bifaciality. Futhermore, widegap chalcopyrites based on sulfides have reached efficiencies that put all-chalcopyrite tandem cells or tandem cells based on Si into reach.

Area 3: Daniel Derkacs, SolAero by Rocket Lab, USA

For the last 10 years, Daniel Derkacs has guided the development of next-generation photovoltaic products for space applications at SolAero Technologies. Daniel has extensive experience in the design and manufacturing of III-V multijunction solar cells, and his responsibilities and interests include epitaxial design & growth, cell processing, cell test & qualification, panel design & layout, in-orbit thermal modeling, and software development. He holds 38 patents related to III-V solar cells and has an additional 70 pending applications. In the past, Daniel was the Cell Design Manager at Solar Junction Corporation where he co-developed world record breaking >42% efficient dilute nitride-based concentrator solar cells. He began his career in photovoltaics as a Principal Investigator at Spire Semiconductor. Daniel earned his M.S. and Ph.D. in Applied Physics/Electrical Engineering from The University of California in San Diego and his B.S. in Electrical Engineering from the University of New Mexico.

Title: Inverted Metamorphic (IMM) Solar Cells for Space Power Applications

Abstract: Over the past 20 years, SolAero Technologies has been an industry leading supplier of III-V solar cells, solar cell assemblies and solar array panels. We have powered over 1,100 satellites and spacecraft, including >100 GEO missions, >900 LEO missions, and 15 lunar and interplanetary missions.

In the early days of space exploration, silicon solar cells powered most satellites. In the late 90’s, the first commercial single-junction GaAs solar cells on inactive Ge substrates became available, offering higher efficiency and improved radiation hardness. Two-junction GaAs/Ge were quickly introduced, followed by three-junction InGaP2/GaAs/Ge or InGaP2/InGaAs/Ge. For nearly two decades, three-junction cells dominated the market, offering Air-Mass Zero (AM0) efficiency improvements from ~26% to ~29% along the way. Today, multijunction solar cells with >30% are available with three, four, and five junctions. These cells offer improved infrared energy conversion and employ sophisticated device architectures based on upright metamorphic (UMM), inverted metamorphic (IMM), and/or strain-balanced superlattice structures.

SolAero’s flagship 34%-class efficiency five-junction IMM-β is the highest performing space-grade solar cell commercially available; and because it employs the IMM architecture, it has a pragmatic roadmap to higher efficiencies. Not only does IMM-β offer the highest power density (W/m2) and specific power (W/kg) at beginning-of-life (BOL), this cell exhibits industry-leading end-of-life (EOL) performance due to its radiation-hard design. In addition, IMM-β is engineered to operate 10°C-13°C cooler than Ge-based cells for typical in-orbit mission conditions. This feature improves the efficiency of the cell throughout the mission compared to values indicated solely by its temperature coefficients. Finally, the cost of manufacturing IMM cells has been significantly reduced, enabling cost/power ($/W) figures-of-merit that are near or below parity with the most advanced three- or four-junction Ge-based solar cells.

State-of-the-art multijunction solar cell technologies and their respective roadmaps will be reviewed, followed by discussions on the complexities and trades that are often made in the design of solar arrays. It will be demonstrated that higher efficiency solar cells, like IMM-β, often result in the lowest cost solution at the solar array and/or the satellite system level as compared to lower efficiency Ge-based cells, even if their $/W cost is greater at the bare cell level.

Area 4: Ivan Gordon, IMEC, Belgium and TU Delft, The Netherlands

Professor Dr. Ivan Gordon is leading the Photovoltaic Technology and Energy Systems group of IMEC in Belgium and is also part-time professor in Digital Photovoltaics at the Delft University of Technology in the Netherlands. Furthermore, he is Editor-in-Chief of the journal Solar Energy Materials and Solar Cells and coordinator of the joint program on Photovoltaics of the European Energy Research Alliance (EERA).

Title: Sustainable Silicon Cell and Module Technology for the Terawatt Era

Abstract: In this presentation, an overview of the state-of-the-art silicon PV cell and module technology will be given. Special emphasis will be placed on the challenge of making silicon PV manufacturing more sustainable and compatible with a worldwide production rate of multiple Terawatts per year. Such a high production and deployment rate will be needed in the coming decades if we want the world to become climate neutral by 2050 but this will not be possible with the current silicon PV technology due to among others the scarcity of certain key materials. Future technology improvements and manufacturing choices will therefore need to be driven mostly by sustainability arguments.

Area 5: Susanna Thon, Johns Hopkins University, USA

Susanna M. Thon is an Associate Professor of Electrical and Computer Engineering and the Marshal Salant Faculty Scholar at Johns Hopkins University.

Title: Spatially-Resolved Multi-Modal Spectroscopy for Defect Identification and Parameter Prediction in Solar Cells

Abstract: Solution-processed materials such as colloidal quantum dots, organic semiconductors, and hybrid perovskites show great promise for next-generation flexible photovoltaics. However, due to their nanostructured nature, films made from these materials often display large-scale inhomogeneity. Additionally, development times are constrained due to the empirical optimization process that involves measuring multiple materials parameters, adjusting fabrication procedures, and repeating to achieve better performance. Here, we demonstrate a micrometer-resolution 2D characterization method with millimeter-scale field of view for assessing solar cell film quality and uniformity. Our instrument simultaneously collects photoluminescence spectra, photocurrent transients, photovoltage transients, current-voltage characteristics, and other optoelectronic properties of interest. We use this high-resolution morphology mapping to quantify the distribution and strength of the local optoelectronic property variations in colloidal quantum dot solar cells due to film defects, physical damage, and contaminants across nearly the entire test device area, and the extent to which these variations account for overall performance losses. We also use the massive data sets produced by this method to train machine learning models that take as input simple illuminated current-voltage measurements and output complex underlying materials parameters, greatly simplifying the characterization process for optoelectronic devices.

Area 6: David Ginger, University of Washington, USA

Currently the B. Seymour Rabinovitch Endowed Chair in Chemistry and Chief Scientist of the University of Washington Clean Energy Institute, David Ginger studies interfaces in thin film photovoltaics. He obtained his Ph.D. in Physics from the University of Cambridge, and B.S. degrees in chemistry and physics from Indiana University.

Title: Scalable Surface Passivation Approaches for Perovskite PV: From Defects to Devices

Abstract: The control of interfacial defects is critical to advance the performance and long-term stability of halide-perovskite-based photovoltaics. In this talk I will discuss the origins of interfacial recombination arising from both native perovskite surface states such as halide vacancies as well as interactions between the perovskite semiconductor and typical charge transport layers. Using a combination of optical spectroscopy, electron and scanning probe microscopy, and a range of surface science tools we characterize the evolution of the perovskite and perovskite/charge transport layer interface, and explore strategies to reduce defect densities in perovskite thin films, while also reducing deleterious chemical and electronic interactions between the perovskite and charge transport layer. These results allow reduction of the surface recombination velocity to less than ~10 cm/s, and demonstration of record voltages in methylammonium-free wide-gap perovskites suitable for integration into tandem cells.

Area 7: Mauro Pravettoni, National University of Singapore (NUS), Singapore

Dr Mauro Pravettoni is Singapore’s convenor of IEC National Committee, member of the British Society for the Philosophy of Science and ISO 17025 Technical Assessor for NATA, the Australian National Agency of Testing Authorities. He got his PhD at the Imperial College, London. Since 2017 he is at the National University of Singapore, where he is director of PV Module for Urban Solar Cluster at SERIS, the Solar Energy Research Institute of Singapore.

Title: Reliability of Modules in Floating Photovoltaics: Stresses, Severities and Tests

Abstract: The recent evidence of the need for a further boost in solar photovoltaic (PV) deployment has triggered actions from policymakers. These are leading to a change of paradigm in the PV community, from established PV applications (mainly rooftop, and utility-scale for commercial PV modules; but also space, indoor PV and gadgets) towards the exploitation of new “integrated” applications. In 2022 our Institute has co-launched the 1st International Integrated-PV Workshop, bringing together worldwide experts of building-integrated PV (BIPV), vehicle-integrated PV (VIPV), agro-PV, floating-PV, and PV integrated into urban infrastructures (noise-barrier PV, PV fences, road-integrated PV, PV shields, PV carports, etc.). Modules designed for these novel PV applications require to rethink the test procedures for their qualification, and new advanced stress tests will be needed to ensure that modules can withstand new specific operational environments. This work will list the environmental features (and associated stresses with severities) that will need to be assessed soon to ensure PV module reliability, with a focus on floating PV applications.

Area 8: Colin Sillerud, CFV Labs, USA

Colin Sillerud is the VP of engineering and head of reliability testing at CFV Labs in Albuquerque, NM. He has both collaborated on and designed IEC test protocols and published research on photovoltaic module mechanical and backsheet durability. He is also active on multiple standards committees such as IEC TS 63209-1, Extended Reliability Testing.

Title:Current Issues in PV Module Reliability Testing

Abstract: Reliability testing for PV modules grows in importance as new technologies proliferate and as installations move into harsher environments. The photovoltaic industry continues to expect module performance and lifetime gains at lower costs by using novel designs, materials and technology. Further, modules are being installed in environments with greater extremes in temperature, humidity and mechanical stresses, while investors require increased confidence in module lifetime predictions. Extended reliability testing, such as IEC TS 63209-1, is used to compare and separate modules into groups of higher and lower reliability. This presentation examines past, current, and future trends in extended reliability testing. Current reliability concerns, such as increased module size, hail resistance, and UVID, will be discussed. Testing considerations for new and future technologies, such as TOPCon, HJT and Perovskites, are also presented.

Area 10: Martin Wild, ETH Zurich, Switzerland

Martin Wild is a climate scientist at the Swiss Federal Institute of Technology (ETH), Zurich Switzerland. His research focuses on solar radiation in the climate system, and its changing availability at the surface over the years. He is a lead author of the 5th and 6th assessment reports of the Intergovernmental Panel on Climate Change (IPCC).

Title: Decadal Variations in Solar Resource under Climate and Air Pollution Change

Abstract: Solar radiation received at the Earth’s surface is the key resource for PV power production. However, there is growing evidence from long-term surface radiation measurements, that this resource is not stable over the years but undergoes substantial multidecadal variations. These include a decrease in surface solar radiation from the 1950s to the 1980s at widespread observation sites, a phenomenon popularly known as “global (solar) dimming”, followed by a more recent partial recovery in some parts of the world, known as “brightening”. A quantification of these variations and understanding of the underlying causes is of importance for solar resource assessments and the long term planning of solar power systems. At many observation sites in industrialized countries, solar dimming and brightening has also been evident under cloud-free conditions, pointing to changing levels of air pollution as major contributor. Specifically, increasing air pollution and associated increase in aerosol concentration are considered as major cause of the decline in solar resources up to the 1980s, while air pollution regulations and mitigation contributed to their more recent recovery in many of the industrialized nations. This presentation will also address potential changes in the future availability of surface solar radiation as projected by global climate models.

Area 11: Izumi Kaizuka, RTS Corporation, Japan

Izumi Kaizuka specializes in analysis of the PV market, policy, industry and business models, and especially has a thorough knowledge of the overseas trends of renewable energy. She serves as the deputy manager and Japan's representative of the Task 1 (Strategic PV Analysis & Outreach) of IEA PVPS, the International Energy Agency Photovoltaic Power Systems Programme. She is also one of the authors of the "Trends in Photovoltaic Applications" released by IEA PVPS Task 1. She serves as the chairperson of the JEMA PV System Standardization General Committee as well as members of various other committees, and also serves as chair of WinPVJ to promote diversity in the PV sector under the efforts of Japan Photovoltaic Society. In November 2017, she has been awarded the “Special Award” at the International Photovoltaic Science and Engineering Conference (PVSEC) for her contribution to international activities.

Title: Trends of Global PV Markets and Industry

Abstract: Global installed capacity of PV power generation reached 1 TW in the first half of 2022 and newly added installed capacity of PV is expected to be 200 GW level for the first time. The global efforts towards decarbonation and competitiveness of PV power over conventional electricity contributed the growth of the PV market. Due to the geopolitical situation, PV power became more and more important for national energy security. In this plenary talk, global trends of the PV market and supply chain will be presented based on Snapshot of Global PV Markets by IEA PVPS Task1 and issues for future growth towards TW PV markets will be discussed.