Did you hear the news about a “breed” of stocks that made investors the richest in 2019?

It’s not housing stocks, which enjoyed a record rally last year. It’s not even everyone’s beloved tech stocks like Netflix or Facebook.

This may sound like a joke if you’ve followed this sector for long, but the hands-down winner of 2019 was solar stocks. Invesco Solar ETF (TAN) ran up 51% in just a year, becoming last year’s best-performing ETF.