Breaking the efficiency barrier: Researchers propose multi-stage solar system to harness the full spectrum

As the global push for renewable energy accelerates, capturing the full spectrum of solar energy remains a significant challenge. Photovoltaic (PV) cells convert light into electricity most efficiently at low temperatures, while photothermal (PT) and thermophotovoltaic (TPV) systems require high temperatures to function. Balancing these opposing thermal requirements in a single system has long hindered the development of hybrid solar harvesters.

In a study published in the journal ENGINEERING Energy, a research team from the State Key Laboratory of Clean Energy Utilization at Zhejiang University has proposed a novel solution: a multi-stage concentrating and spectrum-splitting coupling approach for complementary PV-TPV conversion.

Decoupling Temperature and Concentration The primary innovation of the research lies in its "multi-stage" architecture. In traditional spectrum-splitting systems, all components are often subjected to the same solar concentration ratio, forcing a compromise between PV cooling and TPV heating.

The Zhejiang University team developed a thermodynamic model that allows the system to decouple the concentration ratios for PV and TPV modules. By using advanced spectrum-splitting filters (such as SiO2/TiO2 interference thin films), the system directs high-energy photons to PV cells at lower concentration ratios to maintain efficiency through , while coupling lower-energy photons of multi-stage residual spectra to generate the high-grade thermal energy for TPV conversion.

Key Research Findings The study provides a comprehensive thermodynamic analysis of the system, evaluating its performance from ideal limits to practical application parameters. Key highlights include:

Enhanced GaSb Performance: The multi-stage system using Gallium Antimonide (GaSb) cells outperformed traditional single-stage hybrid systems, particularly at lower initial concentration ratios. Optimized Energy Flow: By separating the light-harvesting stages, the researchers successfully achieved the high heat collection temperatures required for TPV without overheating the PV components. A Pathway to Full-Spectrum Utilization: The model demonstrates a promising pathway for reaching higher overall solar-to-electrical conversion efficiencies by effectively utilizing both visible and infrared light.

Impact on Future Solar Technology "The challenge of full-spectrum solar utilization has always been the thermal conflict between different conversion methods," the researchers noted. "Our multi-stage approach provides a flexible framework that can be optimized for different materials and geographic locations, potentially leading to a new generation of high-efficiency solar power plants." This research offers a critical theoretical foundation for designing decentralized energy systems and industrial-scale solar conversion facilities that require both electricity and high-grade thermal energy.

JOURNAL: ENGINEERING Energy

DOI: https://doi.org/10.1007/s11708-026-1058-0

Article Link: https://link.springer.com/article/10.1007/s11708-026-1058-0

Cite this article: Tian, J., Cheng, Z., Shan, S., Zhang, G., Zhou, Z., & Cen, K. (2026). Thermodynamic analysis of novel solar photovoltaic-thermophotovoltaic complementary conversion method based on multi-stage concentrating and spectrum splitting. ENGINEERING Energy, 20(3), 10580. https://doi.org/10.1007/s11708-026-1058-0

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