An ETF investing in solar energy companies has soared 90% in 2013 after a multiyear downdraft. There are several reasons why the solar ETF’s rally could be in the early innings with plenty of room to run.

The U.S. is increasing solar panel installations, supporting the fledgling photovoltaic industry, along with related exchange traded funds, as we try to wean ourselves off fossil fuels.

Americans are installing one solar photovoltaic system every four minutes, and given current market growth projections, we could be installing one system every minute and twenty seconds by 2016, reports Stephen Lacy for Greentech Media. In comparison, systems were being stalled every 80 minutes in 2006.

GTM Research calculates that about two-thirds of all distributed solar in the U.S. was installed in the past two and half years, and cumulative installations of distributed photovoltaic systems will double by 2016.

With installations going up every 83 seconds, capacity is projected to hit 9 gigawatts by 2016.

Source: Shayle Kann, GTM Research

Source: Shayle Kann, GTM Research

Deutsche Bank’s Vishal Shah, Jerimiah Booream-Phelps and Susie Min are even more optimistic, projecting U.S. solar capacity could hit 50 gigawatts by 2016, reports Rob Wile for Business Insider. However, this would only make up 2% of overall U.S. electricity capacity.

Deutsche Bank attributes the solar industry boom to a number of factors, such as lower costs and increasing competitiveness to traditional retail electricity.