ACAP supported research by UNSW’s Associate Professor Brett Hallam and Dr Yuchao Zhang has addressed one of the big bottlenecks in the upcoming terawatt-scale manufacturing and deployment of TOPCon solar cell technology: the sustainable use of silver.
The team have developed a silver-lean screen-printed contact scheme that is compatible with existing manufacturing infrastructure, and maintains high cell efficiencies.
Dr Zhang said, “A reduction in silver consumption by over 80% down to 2 mg/W for TOPCon with this approach can enable mass production of PV at the multi-terawatt scale each year using existing and proven screen-printing technology, allowing us to deploy sufficient PV to meet net-zero targets.
“At a three terawatt p.a. scale, this could generate savings of up to $30 billion per year.”
Silver is a critical material in screen-printed contacts of solar cells, and its current usage levels are unsustainable. The PV industry already consumes nearly 20% of the global silver supply. With the industry's continued expansion to meet global energy demands, this figure will exceed sustainable thresholds, leading to resource depletion and substantial price increases.
The silver consumption of screen-printed contacts must be reduced to a target level of 2 mg W−1 to allow an upcoming terawatt-scale production of industrial solar cells. The silver-lean screen-printing design presented in their work provides a unique opportunity to achieve such a target without sacrificing efficiencies.
TOPCon (or tunnel oxide passivated contact) solar cells deliver higher energy conversion efficiencies compared to PERC solar cells, and are predicted to dominate the solar PV market, but they also require more silver than PERC cells, due to the use of silver contacts on both the front and rear surfaces.
There are four important benefits to this innovation.
Improved sustainability of silver resources
The proposed solution reduces silver usage in solar cells by up to 50% and offers a pathway to further reductions (below 2 mg/W), significantly alleviating the strain on silver resources.
Lowering production costs
Silver is a large portion (over 60%) of non-silicon cell manufacturing costs, contributing to approximately 8.5% of the total module cost. By reducing silver consumption, Hallam and team’s innovation helps lower production costs, making solar energy more affordable and competitive with other energy sources.
Compatibility with existing manufacturing
Importantly, the proposed new screen-printing method is compatible with existing industrial infrastructure. This reduces the barriers to adoption, allowing manufacturers to implement the technology without major overhauls or additional costs.
Maintaining high efficiency
The silver-lean contact design achieves an efficiency of 24.04% for large-area TOPCon cells, comparable to or better than standard industrial solar cells. This ensures that reducing silver consumption does not come at the cost of performance, maintaining competitiveness. Recently, industrial full-area TOPCon cells with over 26.5% efficiencies have been successfully fabricated in partner’s R&D facilities, as a part of collaborations with industrial partners and effort to accelerate the commercialisation of the developed silver-lean technologies.
The group is working with Fusion New Materials, Toyo Aluminium, Copprint and several leading solar cell manufacturers on this project.
Read more https://onlinelibrary.wiley.com/doi/10.1002/solr.202400478?msockid=37e3573ef9896594384543d2f8656459