Niche ETFs like the solar fund recently launched by Market Vectors are increasingly popular among investors concerned about which companies their portfolios are invested in, especially in today’s socially-conscious environment. But according to Jeffrey Ptak at Morningstar, these funds don’t have the sunny outlook you might expect.

According to Ptak, funds like the aforementioned Market Vectors fund and the Claymore/MAC solar fund invest in companies that rely heavily on government subsidies, and face stiff competition and a lot of it. He cites the volatility at SunPower, which rose 251 percent last year and fell 51 percent last quarter, as an example of why investors should hold off on solar funds, at least until they’re trading well below fair value estimates.

Read more at Morningstar.