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: Shares of China-based solar-panel wafer manufacturer JinkoSolar Holding (NYSE: JKS) jumped as high as 16.1% in early trading today before swooning 2.3% below Friday's closing price, all on very heavy trading volume.

So what: Solar stocks are dropping across the board today on news that heavy solar-power user Italy might cap solar installations at 8 gigawatts total. JinkoSolar has a large exposure to the Italian market, so the afterglow from this morning's fantastic earnings report faded very quickly.

Now what: Rivals LDK Solar (NYSE: LDK) and Yingli Green Energy (NYSE: YGE) were hit much harder than JinkoSolar today, because they didn't have any ameliorating good news to soften the Italian blow. Even so, this might turn out to be a buy-in opportunity on solar stocks in general -- don't forget that the Italian parliament is just thinking about that solar cap for now, and the proposed rule may never get signed into law. Whether you're an opportunistic solar buyer or a panicked seller today, this industry is not for the faint of heart.

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Fool contributor Anders Bylund holds no position in any of the companies discussed here. We Fools may not all hold the same opinions, but we all believe that considering a diverse range of insights makes us better investors. The Motley Fool is investors writing for investors.