Clean energy ETFs are among the top-performers this year as well, after a spectacular performance last year.This comes after a volatile decade, when their performance was largely dependent on government subsidies and oil prices.The cost of renewable energy generation has been falling in recent years with continued technological innovation, and that has started changing the competitive balance between clean and traditional energy.The Invesco Solar ETF (TAN) holds US and international companies in the solar energy industry. Enphase Energy (ENPH) and SolarEdge Technologies (SEDG)—the largest holdings in the ETF—have skyrocketed more than 500% and 200% respectively over the past year.The Invesco WilderHill Clean Energy ETF (PBW) holds US traded companies involved in cleaner energy sources or energy conservation. Tesla (TSLA) is its top holding.The ALPS Clean Energy ETF (ACES) holds US and Canadian based companies that are focused on renewables and other clean technologies.The three ETFs have gained more than 50% in the last 12 months. To learn more about them, please watch the short video above.Want key ETF info delivered straight to your inbox?Zacks' free Fund Newsletter will brief you on top news and analysis, as well as top-performing ETFs, each week. Get it free >> Want the latest recommendations from Zacks Investment Research? Today, you can download 7 Best Stocks for the Next 30 Days. Click to get this free report Tesla, Inc. (TSLA): Free Stock Analysis Report Enphase Energy, Inc. (ENPH): Free Stock Analysis Report SolarEdge Technologies, Inc. (SEDG): Free Stock Analysis Report Invesco Solar ETF (TAN): ETF Research Reports Invesco WilderHill Clean Energy ETF (PBW): ETF Research Reports ALPS Clean Energy ETF (ACES): ETF Research Reports To read this article on Zacks.com click here. Zacks Investment Research Want the latest recommendations from Zacks Investment Research? Today, you can download 7 Best Stocks for the Next 30 Days. Click to get this free report