Image source: Plug Power.

What: Shares of hydrogen technology provider Plug Power Inc. (NASDAQ:PLUG) jumped as much as 16% today after announcing fourth-quarter earnings.

So what: Revenue jumped 78.6% from a year ago to $38.4 million, coming in ahead of the $35.5 million analysts were expecting. GenDrive units recognized in the quarter jumped from 719 a year ago to 1,256.  

On the downside, net loss more than tripled to $25.2 million, or $0.14 per share, partly due to writedowns on service contracts because of faulty products. Adjusting for these one-time items, the company lost $0.05 per share, which is what Wall Street expected.   

Now what: Growth is coming along nicely for Plug Power, but there's still no sign the company is going to turn a profit in the near future. That's what has me concerned today, despite the strong top-line results. Management also recently took out a $30 million loan to help fund future growth. That leaves the company with a strong cash position, but until Plug Power can prove it can generate cash from operations, rather than burn it, I would approach this stock cautiously.