Simon P. Philipps’s research while affiliated with Fraunhofer Institute for Solar Energy Systems and other places

A major renewable-energy milestone occurred in 2022: Photovoltaics (PV) exceeded a global installed capacity of 1 TW dc. But despite considerable growth and cost reduction over time, PV is still a small part of global electricity generation (4 to 5% for 2022), and the window is increasingly closing to take action at scale to cut greenhouse gas (GHG) emissions while meeting global energy needs for the future. PV is one of very few options that can be dispatched relatively quickly, but discussions of TW-scale growth at the global level may not be clearly communicating the needed size and speed for renewable-energy installation. A major global risk would be to make poor assumptions or mistakes in modeling and promoting the required PV deployment a n d i n d u s t r y g r o w t h a n d then realize by 2035 that we were profoundly wrong on the low side and need to ramp up manufacturing and deployment to unrealistic or unsustainable levels.

In this paper, we present a stepped architecture optimized for current matching in high‐voltage laser power converter photovoltaic (PV) cells. The integrated series/parallel connection in stepped PV cells combines the advantages of well‐known multijunction and multisegment approaches with respect to current matching, whereas their specific drawbacks are circumvented. The superior misalignment tolerance of stepped PV cells in comparison with multisegment cells is shown by simulations of the maximum acceptable misalignment (MAM) for a range of devices with various output voltages. We present the first realization of stepped PV cells with two stacked GaAs‐based pn‐junctions. Thereby, the unique properties of the lateral current flow in the bottom cell and the assessment of the optical absorption in the subcells are discussed. Moreover, the effects of segmentation and number of stacked junctions on the I‐V characteristics are investigated. Finally, the behavior towards misalignment of a laser spot is studied for stepped and multisegment PV cells. An optimal current matching for misalignment‐prone power‐by‐light systems is found with a six‐segment stepped PV cell.

Solar energy has the potential to play a central role in the future global energy system because of the scale of the solar resource, its predictability, and its ubiquitous nature. Global installed solar photovoltaic (PV) capacity exceeded 500 GW at the end of 2018, and an estimated additional 500 GW of PV capacity is projected to be installed by 2022–2023, bringing us into the era of TW-scale PV. Given the speed of change in the PV industry, both in terms of continued dramatic cost decreases and manufacturing-scale increases, the growth toward TW-scale PV has caught many observers, including many of us (1), by surprise. Two years ago, we focused on the challenges of achieving 3 to 10 TW of PV by 2030. Here, we envision a future with ∼10 TW of PV by 2030 and 30 to 70 TW by 2050, providing a majority of global energy. PV would be not just a key contributor to electricity generation but also a central contributor to all segments of the global energy system. We discuss ramifications and challenges for complementary technologies (e.g., energy storage, power to gas/liquid fuels/chemicals, grid integration, and multiple sector electrification) and summarize what is needed in research in PV performance, reliability, manufacturing, and recycling.

Technologiebericht "Photovoltaik" des strategischen Leitprojektes "Trends und Perspektiven der Energieforschung" (gefördert durch das BMWi) über den Status, die Perspektiven sowie das Innovations- und Marktpotenzial von verschiedenen Energietechnologien.

This chapter discusses solar cells made of III-V semiconductors, and how they have reached efficiencies of over 46% in 2016, the highest of any photovoltaic technology to date. These high efficiencies are possible due to the ability of stacking solar cells made of different III-V semiconductors. The main focus of current research is on III-V multijunction solar cells with three or more junctions. III-V Solar cells are widely used in space applications, terrestrial concentrators as well as niche markets such as power-by-light or thermophotovoltaics. Today III-V devices find terrestrial applications only under high concentration. But III-V on silicon may be an attractive path to reduce cost and eventually penetrate this high-performance technology into conventional applications of flat-plate photovoltaics.

Blade condition monitoring systems with fiber-optic sensors attract much attention because they are resistant to lightning strikes, a major issue with increasing blade lengths. However, fiber-optic sensor systems are more complex and more expensive than their electronic counterparts. We describe a new blade condition monitoring system, which combines the lightning safety of optical fibers with the reliability and cost-effectiveness of electronic sensors. The optical fibers transport data from the blades to the hub, and in addition, they provide the electrical power for operating the sensor units in the blades. To achieve full protection against lightning-induced electromagnetic fields, an appropriate shielding of the sensor units is required. We present results on the reliability of a newly developed prototype based on optically powered sensors. In a field trial, the unit monitored successfully the blade vibrations of a 1.5 MW wind turbine for a period of 23 months. Copyright

OPEN ACCESS: http://dx.doi.org/10.1002/pip.2814 Dual-junction GaAs laser power converters optimized for one monochromatic wavelength are presented, and their temperature dependence is experimentally evaluated. External quantum efficiency and irradiance-dependent current–voltage measurements (10 to 104 W/cm2) under monochromatic laser light (809 nm) have been undertaken to quantify temperature- and irradiance-dependent effects on the performance. The temperature dependence of the current matching of the two subcells, caused by the temperature-dependent absorbance, is quantified. Losses in performance due to variations in operating temperature for different power-by-light applications are calculated to be between 16.2% and 21.0%. Future potential enhancements in cell performance are discussed. For elevated temperatures, super-linear behavior of the spectral response with increasing irradiance is observed, which is attributed to effective luminescent coupling from the top to the bottom subcell as the device becomes more radiative limited. For low temperatures, where the bottom cell is overproducing, no dependence on irradiance is found, which shows the influence of photon transport losses to the substrate. © 2016 The Authors. Progress in Photovoltaics: Research and Applications published by John Wiley & Sons Ltd.

This paper presents the project Concentrating Photovoltaic modules using advanced technologies and cells for highest efficiencies (CPVMatch), which is funded from the European Union’s Horizon 2020 research and innovation programme. V multi-junction solar cells and CPV modules. Concerning cells, novel wafer bonded four-junction solar cells made of GaInP/GaAs//GaInAs/Ge are optimized with the target of reaching 48% efficiency under concentration at the end of the project. Moreover, multi-junction solar cell technologies with advanced materials - like ternary IV element mixtures (i.e. SiGeSn) and nanostructured anti-reflective coatings - are investigated. Concerning CPV modules the project focuses on both Fresnel-based and mirror-based technologies with a target efficiency of 40% under high concentrations beyond 800x. Achromatic Fresnel lenses for improved light management without secondary optics are investigated. In addition, smart, mirror-based HCPV modules are developed, which include a new mirror-based design, the integration of high efficiency, low cost DC/DC converters and an intelligent tracking sensor (PSD sensor) at module level. A profound life-cycle and environmental assessment and the development of adapted characterization methods of new multi-junction cells and HCPV modules complete the work plan of CPVMatch.

The full set of information on the study "Flexibility concepts for the German power supply in 2050. Ensuring stability in the age of renewable energies" can be found on http://www.acatech.de/de/aktuelles-presse/dossiers/dossier-stromversorgung-2050.html and the main document with the study in English is available on http://www.acatech.de/de/publikationen/stellungnahmen/kooperationen/detail/artikel/flexibility-concepts-for-the-german-power-supply-in-2050-ensuring-stability-in-the-age-of-renewable.html Dieser Steckbrief entstand im Rahmen der Ad-hoc-Arbeitsgruppe Flexibilitätskonzepte des Akademienprojektes Energiesysteme der Zukunft (ESYS). Er dokumentiert die Ergebnisse der Fachgruppe Photovoltaik. Die Ad-hoc-Arbeitsgruppe Flexibilitätskonzepte hat analysiert, wie die Stromversorgung im Jahr 2050 mit einer CO2-Einsparung gegenüber 1990 von 80 bis 100 Prozent gestaltet werden könnte. Dabei lag der Fokus darauf, wie die Versorgungssicherheit in der Stromversorgung bei einem wachsenden Anteil volatil einspeisender erneuerbarer Energien sichergestellt werden kann. Für verschiedene Szenarien wurde untersucht, wie die fluktuierende Stromerzeugung aus Wind und Photovoltaik sinnvoll durch sogenannte Flexibilitätstechnologien – flexible Stromerzeuger, Demand-Side-Management, Speicher und Netzausbau – ergänzt werden kann. Hierbei war es das Ziel, sämtliche Möglichkeiten zur Bereitstellung von Flexibilität zu erfassen und zu charakterisieren, um deren Einsatzmöglichkeiten in unterschiedlich ausgeprägten Stromsystemen im Jahr 2050 zu identifizieren. Um eine valide und aussagekräftige Datenbasis zu erhalten, wurde ein breiter Konsultationsprozess mit Expertinnen und Experten aus Industrie und Wissenschaft durchgeführt. In zehn Fachgruppen wurden die verschiedenen Technologien zur Bereitstellung von Flexibilität analysiert und einer einheitlichen interdisziplinären Bewertung unterzogen.

Starting on June 2011, NGCPV has been the first coordinated project between the European Commission and Japanese NEDO in order to advance in the science and technology of concentrator photovoltaics (CPV). Research has covered all relevant areas in CPV, from solar cells to complete systems, including multijunction solar cells, novel solar cell concepts utilizing nanostructures, advanced optics and modules, thermal management, reliability and modeling at all the stages of the CPV chain, rating and round robin schemes and the development of characterization tools for cells, modules and systems (outdoor and indoor). Ending in November 2014, the NGCPV project has attained some remarkable results, such as the manufacturing of a 44.4% world record efficiency triple junction solar cell (by Sharp Corp.) and the development of a 15 kW CPV system (by Daido, BSQ and UPM) with a DC efficiency of 28% under CSOC, which is the highest reported in the world at system level. In this paper we summarize these and other relevant results concerning project activities such as the investigation of novel buffers for growing III-V materials on silicon, novel ~1eV materials for manufacturing quad-junction solar cells, the development of accurate models to forecast the electricity production in CPV plants and novel advanced optical designs for CPV modules, among others.