Shares of fuel-cell company Plug Power (NASDAQ:PLUG) shot up 30% over the past two days, after the company announced it would be expanding its presence in Wal-Mart (NYSE:WMT) distribution centers, representing a big contract win for the small company. Plug Power currently has about 535 hydrogen fuel cell charging stations in three of Wal-Mart's distribution centers, for use in charging fork lifts and other heavy machinery, and will now be expanding that presence to a total of nine distribution centers. The stock also received analyst upgrades as a result of the contract, further spurring on investor confidence.

But the size and former market capitalization of the company raise some questions. With the stock's 52-week low of $0.14 per share, many still question the legitimacy of the company, despite the potential for its disruptive technology showing much more promise over the past year. This contract with Wal-Mart lends a lot of the credibility to Plug Power that investors were hoping for.

On today's Stock of the Day, host Mark Reeth and Motley Fool energy analyst Taylor Muckerman take a look at Plug Power, and whether it looks like a buy today. Early investors who bought at the low have seen eye-popping gains of over 4,000% in the past year, but while Taylor says he'll definitely be keeping a close eye on the stock, he wants to see the dust settle a little more around this one before he buys in.