When Bloomberg New Energy Finance (BNEF) released their clean energy league tables for 2010, the top of the list was my favorite exchange traded fund (ETF), the Powershares Cleantech Portfolio ETF (AMEX: PZD), with an annual return of 7.6%. Second place was the Winslow Green Growth (WGGFX) mutual fund (7.4% return), which is one of what I consider to be the three best clean energy mutual funds.