Although we don't believe in timing the market or panicking over market movements, we do like to keep an eye on big changes -- just in case they're material to our investing thesis.

What: Solar stocks are having another rough day today, and Yingli Green Energy (NYSE: YGE) is dipping 10% along with many of the industry's leaders.

So what: The news out from Yingli is that one of the company's independent directors, who's also a member of its audit committee, has stepped down. But the bigger news came out of JinkoSolar (NYSE: JKS), which shut down a plant after regulators found it may be polluting a river.

Now what: As if the solar industry needed another black eye after the Solynra debacle, now it looks like pollution should be a larger concern than originally anticipated. Residents protested during the weekend over dead fish in a nearby river.

If you needed another reason to stick with U.S. solar manufacturers, who hypothetically operate more stringent facilities, now would be a good time to consider them over Chinese manufacturers. First Solar (Nasdaq: FSLR) and SunPower (Nasdaq: SPWRA) have long been this Fool's top pick out of solar manufacturers and should provide less risk than Chinese manufacturers.

Interested in more info on Yingli Green Energy? Add it to your watchlist by clicking here.