Dutch-German consortium developing simplified tandem solar modules

15 Mar 2023

Module consists of solar cells made of sandwiched monolithic perovskite-silicon layers.

In cooperation with Dutch and German industrial partners, research center TNO is developing a novel tandem solar module for early market introduction. The module consists of monolithic perovskite/silicon solar cells layered on top of each other. This arrangement can achieve higher efficiencies than those achieved by current silicon-based solar modules, which results in more power per square meter and lower cost per kWh, say the partners.

FIT4Market, a four-year research project granted by the Netherlands Enterprise Agency, is intended to drive CO₂ reduction through to 2030, thus supporting national climate objectives. Besides that, the project is aiming to bring PV production back to Europe and rebuild a competitive PV supply chain, says this week’s statement from TNO.

Typically, PV modules are increasing their average conversion efficiency by 0.5% per year. This progress results in the continuous reduction of the price per kWh of PV energy production. However, the power conversion efficiency of conventional silicon-based PV modules is set to reach its technological limit within three to five years, adds the statement: “It will become increasingly costly to maintain this positive trend, which is bound to slow down.”

Tandem design

Tandem devices can reach higher efficiencies than single junction solar cells because of an improved utilization of the solar spectrum. The currently emerging tandem cells combine commercial silicon technology for the bottom device, with perovskite technology as the additional layer. Perovskite offers highly efficient conversion of ultraviolet and visible light and excellent transparency to near infrared light. The FIT4Market project is aiming to develop a simplified approach of the tandem technology to accelerate the market introduction.

“The purpose of the collaborative FIT4Market research project is to identify best-practice two-terminal cell development using perovskite and silicon cells in order to develop tandem modules with a competitive LCOE and industry-leading reliability and performance,” said Jorg Muller, Head of cell R&D at Qcells. “Qcells will supply its silicon cell expertise to the project, with our Benelux team overseeing field-testing to measure real world energy performance and yield.”

Maarten Ribbens, Head of TNO Benelux, said, “Qcells current market position is a result of a deep understanding of the addressable market and customer needs. We are extremely excited and happy to be part of this consortium to support the development of this novel solar technology. TNO has been developing its tandem technology since 2016 and a handful of industrial partners eventually hope to deploy this technology in mass production. However, tandem PV module technology requires further development at relevant scale before it is industry-ready for introduction into the market.”

Gianluca Coletti, Program manager of Tandem Technology and Applications, at TNO, said, “The monolithic tandem cell technology used in this project is based on commercial PERC [Passivated Emitter and Rear Cell] c-silicon cells with planar front side, avoiding complexity in dealing with silicon surface texture. The modules will also be bifacial, to increase the current and energy yield and, furthermore, will feature a glass-glass encapsulation for protection of the perovskite cells against moisture.”

New PV era

The TNO statement this week said, “The FIT4Market project will validate that tandem module based on currently used PERC bottom cells are industrially manufacturable, competitive in efficiency and cost and competitive in stability. Further, field tests will provide data to enhance bankability; and the project will also interact with end-users of the new technology.

“The Dutch PV market is especially keen for innovative products due to limited availability of land in the Netherlands, and the opportunity to optimally utilize commercial rooftops for power generation. All these will provide support for further deployment of the technology in Europe. It is expected that as a result, PV module power conversion efficiency can reach over 300Wp/m² [conventional modules today perform in the lower 200Wp/m² range].”