TNO’s bifacial solar cell design enables greater electricity yield

Netherlands-based research center TNO has demonstrated for the first time that bifacial tandem solar technology can be manufactured at what it calls “industrial scale”, generating significantly more electricity per square meter. The breakthrough was achieved together with Dutch industrial companies Levitech, Tempress, Yparex, SMIT Thermal Solutions, and Hanwha Q Cells, Germany.

This new power generation concept, featuring innovation at both cell and module level, can be manufactured using industrially-compatible processes and delivers measurably higher energy output under realistic conditions, says TNO.

The tandem solar module consists of monolithic perovskite/silicon solar cells stacked on top of each other. This architecture achieves higher efficiencies than current silicon-based solar modules, resulting in more power per square metre and lower cost per kWh.

The energy transition requires a rapid increase in renewable electricity production, while available space for solar installations is becoming increasingly scarce. This challenge is particularly visible in urbanized regions and on large commercial and industrial rooftops, where the available surface area is fixed – meaning that increasing the electricity yield per square meter is a priority.

Bifacial solar panels, which capture light at both the front and the rear, already contribute to higher total output. Tandem devices go a step further by improving utilisation of the solar spectrum, enabling efficiencies that single-junction solar cells cannot reach. The current tandem architectures integrate perovskite technologies with existing commercial silicon technologies.

‘Best of both worlds’

Within the Fit4Market project TNO and its partners have focused specifically on combining the best of both approaches: bifacial light capture and tandem cell architecture and doing so at a scale that is relevant for industry. Rather than maximising laboratory efficiency, the emphasis was placed on scalability, integration with current technologies, and validation under practical conditions.

TNO’s announcement stated: “Testing has shown that the bifacial tandem approach delivers 15–30% higher power output compared to conventional bifacial silicon modules used as a reference. The first energy yield measurements from a rooftop installation confirm an approximately 16% increase in annual electricity generation.”

A physical demonstrator has been installed in The Netherlands and is currently undergoing outdoor validation, with a second generation of prototypes now on the roof providing ongoing data under real operating conditions.

Valerio Zardett, Senior Scientist at TNO, commented, “By focusing on industrial processes and bifacial design optimisation, we show that higher power density is achievable in practice. This is a key step towards making bifacial tandem solar technology relevant for large-scale deployment.”

The technology addresses two distinct deployment logics: generating more energy within a fixed footprint, or generating the same amount of energy within a smaller footprint than conventional technology requires. This makes it particularly suited to space-constrained urban and industrial environments.

For optimal performance, the technology is recommended for installations with an albedo (that is the ratio of reflected radiation to incident radiation) of 10–20%. The bifacial design can be further customised to match specific site conditions and local reflectivity, offering flexibility across deployment environments.

The Fit4Market project is coordinated by TNO and brings together industrial partners from the Netherlands and Germany across the photovoltaic value chain. The project is supported through the Dutch Topsector Energy program.

The next phase will focus on further scaling, longer-term outdoor validation, and continued collaboration with industry to prepare the technology for broader application.