Outside the Box: After underperforming the stock market for years, alternative energy is red hot

Clean-energy stocks and exchange-traded funds are on a tear this year, sharply outperforming the broader market and traditional fossil-fuel investments.

The clean-tech ETFs with the most powerful year-to-date rallies include Invesco Solar ETF, up 81% through Thursday; First Trust NASDAQ Clean Edge Green Energy Index Fund , up 58%; and iShares Global Clean Energy ETF , up 41%. Compare that to SPDR S&P 500 ETF Trust , which is up 1.99%, and the Technology Select Sector SPDR Fund , up 23%.

The…