TNO achieves copper-metallized silicon heterojunction solar panels

07 Oct 2025

“Breakthrough” in silicon solar cell metallization enables application of narrow copper lines on front and back of cells.

Cu-metallised Si heterojunction solar cell. Click for info.

Netherlands-based research lab TNO has succeeded in applying copper electrodes to silicon heterojunction solar cells using a new screen-printing process. With this innovation, TNO says, almost the same amount of electricity can be generated as with the traditionally used silver.

The use of copper makes solar cell production both cheaper and more sustainable, while also providing resilience against future silver scarcity and price increases. These results were presented at the European Photovoltaic Solar Energy Conference (EUPVSEC) in Bilbao, in September.

Copper-bottomed

Performance of solar cells with copper-metallization is comparable to those with silver-metallization, say the researchers: “The new process, using the existing screen print production technology, enables the application of very narrow copper lines on both the front and back sides of the solar cells. The performance of these copper-metallised cells is within 1% of traditional silver-metallized cells,” said the TNO statement.

Copper is currently 100 times cheaper and 1,000 times more abundant on the market than silver, enabling solar production to scale up sustainably without reliance on that scarce resource. However, global demand for solar energy is growing rapidly.

TNO says that by 2035, annual addition of PV systems could reach nearly 1 TW. At such a scale, up to 50% of annual global silver production would be needed for solar cells alone.

The research was carried out in close collaboration with Dutch PV start-up MCPV B.V. and a company specializing in metallization pastes.

Yu Wu, Principal Investigator at TNO’s Solar Energy Group, commented, “This result opens an important opportunity, in parallel to copper electroplating technology, for silver-free metallisation in the HJT solar cell manufacturing without extra investments in equipment or added process complexity. It also shows strong potential for future high-efficiency perovskite-silicon tandem solar cells.”

Next steps

TNO is continuing work on improving the copper metallisation process, developing advanced solar module technology compatible with this method, and testing the long-term reliability of the resulting modules. Because the method uses screen-printing technology, industrial implementation is expected to be relatively straightforward. Together with partners like MCPV, work is underway to ensure rapid and sustainable industrial application.

Benjamin Strahm, CTO of MCPV, said, “This result is indeed very important for sustainable heterojunction scale-up. Reducing the silver cost and availability burdens at little efficiency penalty, while using standard manufacturing technologies is offering a fast-track introduction into production.”

These results were achieved with support from the SusCon project, partly funded by TKI Urban Energy, part of the Top Consortia for Knowledge and Innovation (TKIs) of the Netherlands’ Ministry of Economic Affairs and Climate Policy, and SolarNL, funded by the National Growth Fund.