“This year’s runup in clean energy ETFs highlights the volatility of these investments, which have had years of horrible underperformance. Even with the recent jump, both ETFs have underperformed the S&P 500 by more than 100 percent since 2009,” Balchunas said of GEX and TAN.

When it comes to solar ETFs, volatility is the price to pay for increasingly sturdy fundamentals.

China is planning to install as much as 17.8 gigawatts of solar power this year, or two-and-a-half times the capacity added by the U.S. in 2014 as part of the country’s aggressive plans to cut carbon emissions. For instance, the country’s recent move away from small coal plants will avoid the annual release of as much as 11.4 million metric tonnes of carbon dioxide, which could help cut emissions for the first time in over a decade, Today Online reports. [China Initiative Drives Solar ETF Higher]

TAN has a standard deviation of 43.2% while KWT’s three-year standard deviation is 37.1%

Market Vectors Global Alternative Energy ETF