ROCHESTER, N.Y.—Natcore Technology Inc., a New Jersey based solar company, announced the development of a breakthrough solar cell structure earlier this year that greatly reduced the need for silver in solar cells. Now, the company’s researchers have found a way to eliminate silver from mass-produced solar cells altogether.
The technology relies on an all-back-contact silicon heterojunction cell structure in which silver has been replaced using much less expensive aluminum. The substitution was made without any loss of performance, which will allow material costs to be reduced significantly.
“Within the past month, our scientists have wrought historic changes in the architecture and the economics of the solar cell,” Chuck Provini, Natcore president and CEO said. “Solar cell manufacturers will no longer be subject to the vagaries of the silver market. We are now able to produce solar cells at a substantial cost savings thanks to improvements achievable by our proprietary laser technology. We expect to file a provisional patent application within the next two weeks.”
In the most basic sense, when sunlight hits a silicon cell, it generates electrons, and since practical solar cells have been manufactured, silver has been used as a conductor to collect these electrons in order to form a useful electric current. Silver was originally chosen for this role because it is a high-conductivity metal.
Natcore said the average solar panel uses about one-half of an ounce of silver, meaning the metal represents more than 48 per cent of the metallization cost of a solar cell, or about 11 per cent of the total raw material cost of a solar module. At today’s prices, silver costs about US$15.28 per troy ounce. The same quantity of aluminum costs $0.05, about 0.3 per cent of the cost of silver.
Though it is necessary to use twice as much aluminum as silver to achieve an equal amount of conductivity from cell to cell, the raw material cost of aluminum is still more than justified at that differntial.
Natcore’s novel design allows for aluminum to be easily substituted for silver. Natcore scientists used their proprietary laser technology to apply contacts to the rear of the cell as well as for other critical aspects of the process.
The company noted that roughly 1.5 million ounces of silver are currently required to generate 1 gigawatt of solar power. That demand translated into roughly 60 million ounces of silver in 2014, or about 6 per cent of the total demand for the metal. Demand was projected to rise to 15 per cent of the total market in 2018.