Exclusive: A start-up offers copper paste as a cost-effective alternative to silver in solar panels


In the solar energy industry, silver is a crucial material in the manufacture of photovoltaic panels. The silver is transformed into a paste which is loaded into the silicon wafers inside the panel. When sunlight shines on the panels, the silicon releases the electrons and the silicon carries solar electricity through a current that powers a building or goes to a solar battery for storage.

As the demand for solar power installations has increased over the past few years, the demand for silver used in panels has also increased. Silver use in photovoltaics increased 13% to 113.7 million ounces from 2020 to 2021, according to data from the silver institute, which also observed that the global demand for silver in 2021 reached 32,627 tons, surpassing the pre-pandemic environment to reach the highest level since 2015. Industrial manufacturing increased by 9.3% to reach 15,807 tons Last year.

“This primarily reflected the effects of a resumption of industrial operations and the reopening of businesses as economies began to recover from COVID,” the Silver Institute said in its data report. “Other supporting factors included demands from the work-from-home economy, a boom in consumer electronics, investment in 5G infrastructure, inventory build-up along the supply pipeline, and increased end use in the green economy, mainly in photovoltaics.”

But as demand increases, prices rise. The Silver Institute also reported a 22% year-over-year increase in silver prices in 2021, hitting a nine-year high of $25.14 per troy ounce. As silver prices and demand increase, the price of photovoltaic panels will also be impacted.

A different solution: One solution to dealing with rising silver prices is to swap it for copper, a significantly cheaper metal that is widely used in transmission and power generation. While copper prices have risen — $4.24 per pound in 2021, up 50% from 2020, about 6% higher than the 2011 record high of $4.01 per pound — it is still considerably cheaper than silver.

And it’s there Bert Thin Films comes in. Co-founded in 2015 by Dr. Thad Druffelprofessor of engineering at Kentucky’s University of Louisvilleand post-doctoral researcher Ruvini Dharmadasa, the mission behind Bert Thin Films is to promote copper paste called “CuBert” as a solar panel material. The company has its roots in the university’s Conn Center for Renewable Energy Research and is now an independent private entity.

According to the company, the production of CuBert is identical to the process used today with silver – the metal is printed and fired in the same way as silver paste, with the same screen printing equipment and the same ovens. tape currently used by solar panel manufacturers. Since the process is a direct plug-and-play replacement that does not require new technology or machinery, the cost savings are realized immediately.

“The idea of ​​using copper as a replacement for silver has been an industry target for several years,” Druffel told Benzinga. “There are known issues with copper degrading solar cell efficiency over time, and previous attempts to use copper as a conductor on solar cells have failed. My co-founder and I discussed the cons. -measures that could solve the problem of copper-induced degradation several years ago and we came up with a concept that is a commercial alternative to silver.

Druffel pointed out that copper is “nearly 1% of the cost of silver and is considerably more abundant than silver”. But cheaper does not mean that copper is less efficient.

“Copper has almost the same conductivity as silver, so it will produce the same performance,” Druffel added.


Thad Druffel

Growing a start-up: Bert Thin Films began in earnest in January 2015 with a $225,000 grant from the national science foundation designed to enable the manufacture and commercialization of the process for creating copper paste. The Kentucky state government followed three months later with a $100,000 grant. The company received $1.5 million in state and National Science Foundation grants in 2019 to further fund its work, while the U.S. Department of Energy Office of Solar Energy Technologies awarded a $1 million grant in August 2021.

The investment community has also taken notice – earlier this year the company secured $1 million in angel investment. Druffel said he has no plans to entice Bert Thin Films to go public at this time, stating that “the company’s current funding, combined with growing support from industry partners, is sufficient”.

At the moment Bert Thin Film production is still in the testing phase, with Druffel reporting an initial enthusiastic response from solar panel manufacturers evaluating the product.

“We currently produce CuBert paste at our Louisville plant which is used to test solar cells from major global manufacturers,” Druffel said. “We plan to continue production in Louisville for the foreseeable future.”

And while Druffle recognized that his company’s copper paste could be adapted to other situations, he is strictly focused on his current mission.

“Yes, there are other opportunities, but right now solar power is the biggest opportunity,” he said.

Photos: Top photo courtesy of Bert Thin Films, photo by Thad Druffel courtesy of Conn Center for Renewable Energy Research at the University of Louisville.

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