After the Organization of Petroleum Exporting Countries decided to keep output quotas unchanged, silver exchange traded funds plunged Friday, weakening on the diminished inflation outlook and potentially lower demand from the solar sector.

On Friday, the iShares Silver Trust (NYSEArca: SLV) and ETFS Physical Silver Shares (NYSEArca: SIVR) declined 6.5%.

COMEX silver futures fell 6.3% Friday to about $15.6 per ounce, heading for their biggest drop in 14 months.

OPEC’s decision to maintain its supply out sent West Texas Intermediate crude oil futures to around $67.9 per barrel Friday. The lower energy prices will help pressure consumer prices and diminish demand for precious metals as an inflationary hedge. [Expect a Brutal Day for Oil ETFs]

“Precious metals declined as lower oil prices prompted concerns about deflation,” ANZ analyst Victor Thianpiriya said in a Reuters article.

The SPDR Gold Shares (NYSEArca: GLD), the largest physically backed gold ETF, only dipped 2.4% Friday, as COMEX gold futures was down 1.9% to $1,175.4 per ounce.

Unlike gold, silver sees heavy industrial demand. For instance, silver demand for fabrication in the solar panels industry is expected to outpace photography demand for the first time, writes Frank Holmes, CEO and CIO of U.S. Global Investors, for Investing. Specifically, every photovoltaic panel includes about 15 to 20 grams of silver.

However, falling energy prices diminish the economic competitiveness of solar panels as an alternative energy source.

The Guggenheim Solar ETF (NYSEArca: TAN) fell 5.0% Friday, following OPEC’s decision.

“We believe that part of the solar sell-off may be driven by the fall in oil prices,” Canaccord Genuity analyst Josh Baribeau said, Investor Business Daily reports. “We have never liked the psychological correlation between solar stocks and oil, but it exists to some degree.”

iShares Silver Trust

For more information on the silver market, visit our silver category.

Max Chen contributed to this article.