SunDrive sets 26.07% efficiency record for HJT cell in mass production setting


Sydney-based SunDrive said it had teamed with China-headquartered heterojunction (HJT) equipment manufacturer Maxwell Technologies to demonstrate what it said is “the future potential for HJT solar cell efficiencies exceeding 26% in mass production”.

SunDrive announced on Thursday it had recorded a solar cell efficiency of 26.07% on a full-size silicon HJT solar cell featuring the company’s technology – which replaces the expensive silver used in conventional solar PV cells with cheaper and more abundant copper – using large-scale production processes provided by Maxwell Technologies.

SunDrive, which set a new world record for commercial-sized silicon solar cell efficiency in September, said its latest result has been officially verified by Germany’s Institute for Solar Energy Research (ISFH)

The result is more than 0.5% higher than the 25.54% world-record achievement announced by the company last year, with SunDrive saying improvements had been observed in open-circuit voltage (Voc), short circuit current (Isc) and fill factor (FF).

The improvement in efficiency is the result of “several equipment and processing upgrades,” the company said in an emailed statement.

A plot of the measured current-voltage characteristics under standard test conditions.

Image: SunDrive

SunDrive said Maxwell’s latest generation chemical vapor deposition (CVD) equipment for microcrystalline silicon layer deposition, and an innovative physical vapor deposition (PVD) coating process to create high mobility transparent conducting oxide (TCO) layers were both adopted for the batch of cells.

The metallisation of the HJT cell, with a total area of 274.3cm2 (M6 size), was performed using SunDrive’s “latest generation of direct copper plating technology which achieves finer feature sizes and superior aspect ratios compared to commercial silver screen-printing technologies”.

Silver is a key component in today’s solar panels with estimates indicating solar panel manufacturing accounts for about 20% of the world’s annual consumption of the precious metal. That volume is expected to increase as the next generation of high-efficiency cells currently being developed require up to three times more silver than their antecedents.

SunDrive’s solution, developed by co-founder and chief executive Vince Allen during his PhD at the University of New South Wales (NSW) in Sydney, has been to replace the precious metal with copper.

SunDrive founders David Hu (left) and Vince Allen.

Image: SunDrive

Allen said for solar to reach its full potential, solar cells need to be more efficient, and copper is the key to unlocking the floodgates of more efficient solar cell structures.

“Copper is around 100 times cheaper per kilogram and around 1,000 times more abundant than silver,” he said.

“And aside from the abundancy and cost benefits of copper, we have found we can improve the efficiency above and beyond what is attainable with silver.”

The company, which in December successfully fabricated its first full-size panel, said it is planning to establish cell and module production operations in Australia by the end of 2023 to provide for the nation’s rooftop solar PV market and future utility scale projects.

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