Tandem - Page 2

Cornell University researchers have evaluated the environmental and resource-saving potential of integrating perovskite tandem photovoltaics into agrivoltaic (AgV) lettuce production systems across the United States, revealing a pathway toward “net-negative” agricultural emissions under favorable conditions.

The team conducted a comprehensive “farm-to-fork” life-cycle assessment that links photovoltaic performance with agricultural production, water use, and supply-chain impacts. The analysis covers perovskite-silicon (P-S) and all-perovskite (P-P) tandem technologies, benchmarked against conventional silicon PV, and incorporates region-specific data on irrigation, yields, transport, and food waste. It also accounts for circular recycling and remanufacturing within a closed-loop solar economy framework, alongside avoided grid emissions from on-site electricity generation. 

Fraunhofer ISE, in collaboration with Oxford PV, has developed advanced shingled perovskite-silicon (perovskite-Si) tandem PV modules under Germany’s government-backed HoTSun research initiative.

The glass-glass monofacial Matrix Shingled tandem module. (Photo Credit: Fraunhofer ISE)

The modules were fabricated at Oxford PV’s pilot production facility in Brandenburg an der Havel, where the company supplied its perovskite-Si tandem cells. These cells feature a perovskite top layer, only a few hundred nanometers thick, deposited on a heterojunction (HJT) silicon bottom cell using thin-film processes. While average tandem cell efficiencies were not disclosed, Fraunhofer ISE highlighted the technology’s theoretical efficiency potential of up to 43.3%, significantly higher than the current 29.4% silicon limit.

France's Institut Photovoltaïque d'Île-de-France (IPVF) and Delft University of Technology (TU Delft) in the Netherlands have jointly demonstrated a power conversion efficiency of 31% on a 4 cm² two-terminal (2T) monolithic perovskite/silicon tandem solar cell. The device combines a nanotextured silicon heterojunction bottom cell fabricated at TU Delft with a perovskite top cell deposited at IPVF by slot-die coating in ambient air.

The team chose a unique deposition route. Several groups have already pushed tandem cells past the 30% mark, but many of those records rely on laboratory-scale deposition techniques. Here, the perovskite layer was applied using ambient-air slot-die coating, a process the teams describe as far closer to industrial manufacturing - making the demonstration a meaningful step toward commercially scalable, high-efficiency tandems.

Trina Solar has announced its first commercial order for high-efficiency perovskite/crystalline silicon tandem photovoltaic modules from a global high-end distributed PV customer, marking a major milestone in the commercialization of tandem solar technology. The project, deployed in New Zealand, represents the first time Chinese-developed tandem PV products have entered the global premium residential market.

According to the company, this development reflects the completion of Trina Solar’s full innovation cycle - from laboratory research and standardized product development to large-scale global commercialization. The modules supplied are based on Trina Solar’s 900W+ tandem technology platform and are designed as fully standardized industrial products rather than laboratory prototypes. They meet global residential installation standards and are suitable for batch delivery, representing a transition from experimental devices to commercially viable solutions.

An interview with Dr. Bin Fan, Founder and Chairman of GCL Optoelectronic, took place at a recent conference, providing interesting updates and shedding light on GCL’s perovskite commercialization strategy and 4‑terminal tandem roadmap. 

According to the interview, 2026 is set to be GCL’s first year of mass production for perovskite modules, following the installation of a 500 MW production line in 2025 that is now ramping up. GCL expects to start shipping products by the end of Q3 2026, with a first‑year shipment target of about 50-70 MW - still small compared with mainstream silicon, but a meaningful initial commercial volume for perovskite. The company is focusing on “universal” glass‑based modules designed as a common platform that can serve utility‑scale, distributed generation and residential segments, and that can later be transferred to other substrates, including flexible products.

Researchers from City University of Hong Kong, the Hong Kong University of Science and Technology, Southern University of Science and Technology and the University of Oxford have developed a PEDOT:PSS-free interface strategy that simultaneously boosts efficiency and stability in all-perovskite tandem solar cells.

All-perovskite tandems are widely regarded as a pathway to surpass single-junction efficiency limits thanks to band-gap tunability and strong optical absorption. However, their practical deployment has been constrained by the instability of mixed tin-lead (Sn-Pb) narrow band-gap subcells, particularly when using the conventional PEDOT:PSS hole-transport layer. This material is hygroscopic, exhibits parasitic absorption in the near-infrared, and - critically - interacts with processing solvents during film formation. Using in situ characterization techniques, the researchers show that PEDOT:PSS induces a solvent–underlayer interaction that traps the perovskite film in a metastable state during crystallization. This leads to pronounced phase segregation in the mixed Sn-Pb system, generating compositional heterogeneity and defect-rich films that accelerate degradation and reduce device performance.

Researchers at Nanjing University, National Innovation Institute of Defense Technology, Chinese Academy of Sciences, University of Science and Technology of China and Renshine Solar have developed a new interconnecting strategy for all-perovskite tandem solar modules that directly tackles one of the key bottlenecks to commercialization: the conventional gold-based tunnel recombination junction (TRJ). 

Gold TRJs, while conductive and stable, introduce strong parasitic absorption in the near‑infrared and suffer from interfacial instability, which together limit photocurrent generation and long‑term device durability. By replacing this stack with a fully solution‑processed, oxide-based interconnecting layer, the team shows that it is possible to combine high efficiency, large area, and improved operational robustness in a single device architecture.

Researchers at City University of Hong Kong, Syracuse University and King Abdullah University of Science and Technology (KAUST) have developed an integrated perovskite/silicon tandem photoelectrochemical (PEC) system capable of driving both unassisted water splitting and selective CO₂-to-liquid-fuel conversion, addressing key bottlenecks in photovoltage, interfacial losses, and catalytic overpotential.

At the core of the system is a high-voltage tandem photoanode that combines a wide-bandgap (1.68 eV) triple-cation perovskite top cell, Cs_0.05FA_0.8MA_0.15Pb(I_0.75Br_0.25)₃, with a double-sided textured crystalline silicon (c-Si) bottom junction (1.12 eV). The perovskite absorber is engineered with a carbazole additive (0.5 mg mL⁻¹), which passivates grain-boundary defects and suppresses halide migration, leading to improved film uniformity and reduced non-radiative recombination. As a result, the single-junction device achieves a power conversion efficiency of 22.18% (VOC = 1.227 V, JSC = 21.04 mA cm⁻², FF = 81.2%), along with extended carrier lifetimes (from 972 ns to 1.642 μs) and improved interfacial energetics.

Trinasolar has announced a new world record for a perovskite/crystalline silicon tandem solar module, achieving a peak power output of 907W and a full-area module efficiency of 29.2%. The module performance has been independently verified by TÜV SÜD.

The record-breaking module is based on Trinasolar’s 210 mm large-area tandem cell technology platform and uses an industry-standard, full-size module area rather than a lab-scale demonstrator. According to the company, the R&D team focused on improving perovskite thin-film uniformity, enhancing interfacial passivation and optimizing spectral absorption matching in the tandem stack, which together enabled higher conversion efficiency and better operational stability.

Hanwha Qcells has announced that it will supply its perovskite-silicon tandem solar cells for a lunar surface solar power demonstration project, aiming to test the technology’s viability in the harsh conditions of space. Hanwha Q CELLS GmbH, the company’s German unit, will provide perovskite-based tandem cell samples for the Space Science & Technology Evaluation Facility - First Flight Lunar In-Situ Solar Cell Experiment (SSTEF-1), a project funded by NASA and led by US-based Aegis Aerospace Inc.

The Georgia Tech Research Institute (GTRI), a nonprofit applied research unit under the Georgia Institute of Technology, selected Hanwha Qcells’ tandem devices for this mission to evaluate solar cell performance beyond Earth. The samples will be mounted on the surface of a lunar lander and exposed directly to the space environment, including vacuum, extreme temperature swings, ultraviolet radiation and cosmic radiation, in order to gather real-world performance and reliability data.