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 MEMC Electronic Materials (NYSE: WFR), which makes solar-panel and semiconductor wafers, jumped 12.1% on heavy volume this morning.

So what: The company actually missed analyst expectations but more than made up for that with a tremendously optimistic outlook on 2011. The report not only game MEMC a rocket boost, but also gave a push to solar-panel rivals from Trina Solar (NYSE: TSL) to SunPower (Nasdaq: SPWRA).

Now what: MEMC's projections could be right or they could be wrong, but management would have to make a lot of faulty assumptions in order for 2011 to be anything but a good year in the solar-power industry. However, MEMC's stock looks expensive in relation to its habitually weak earnings and the best play on the sector probably lies elsewhere. Valuation matters, even in a hot sector.

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