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Researchers from the University of New South Wales (UNSW), Sydney have discovered that the current reduction in silver consumption is not sufficient to offset the growing demand from the photovoltaic sector. They recommend increased investment in developing “silver-lean,” photovoltaic technologies.
The study, titled “The silver learning curve in photovoltaics and Projection of silver demand for net zero emissions by 2050”, was done by the team to examine the effects of different PV technology paths on silver demand.
The clean energy transition could see the cumulative installed capacity of photovoltaics increase from 1 TW before the end of 2022 to 15–60 TW by 2050, creating a
significant silver demand risk.
The research present a silver learning curve for the photovoltaic industry with a learning rate of 20.3 ± 0.8%. Maintaining business as usual with a dominance of p-type technology could require over 20% of the current annual silver supply by 2027 and a cumulative 450–520 kt of silver until 2050, approximately 85–98% of the current global silver reserves.
A rapid transition to higher efficiency tunnel oxide passivated contact and silicon heterojunction cell technologies in their present silver-intensive forms could increase and accelerate silver demand. As we approach annual production capacities of over 1 TW by 2030, addressing the silver issue requires increased efforts in research and development to increase the silver learning rate by 30%, with existing silver-lean and silver-free metallisation approaches including copper plating and screen-printing of aluminium and copper.
Emerging next-generation high-efficiency n-type TOPCon and SHJ solar cell technologies, with record efficiencies of 25.5% and 26.3% for two-sided contact devices, respectively, have a substantially higher requirement for silver. The current industrial implementation of TOPCon uses silver for the rear n-type contact as well as silver/Al for the front p-type contact to balance between optical and electrical resistive losses, which results in a silver consumption of 20.4–26.0 mg/W, 30–80% higher than that of PERC. SHJ solar cells use a low-temperature silver paste for both contacts with silver consumption reported in the range of 30.3–37.4 mg/W, more than double that of PERC.
According to the researchers, copper plating is a promising way to reduce silver consumption in the photovoltaic sector. Recycling older solar modules could be a good source of silver over the long-term. This study found that investment in research is crucial. It may take decades before photovoltaic scrap processed enough to make up more than a small amount of new silver.
The team cautioned against relying upon increased silver production as the best silver resources are already mined. This means that opening new mines could mean digging deeper and processing lower-quality ores and all of which will lead to higher energy consumption.