As an alternative energy investor, I'm often guilty of overlooking some of the companies outside of the sector's spotlight. First Solar (Nasdaq: FSLR) and Chinese PV manufacturers grab a lot of headlines, but we don't want to overlook some companies making our energy future possible. Here are four companies worth watching in 2011.

1. SatCon Technology (Nasdaq: SATC)
If 2011 does end up being solar's year, SatCon Technology will end up supplying a lot of inverters for growing solar projects like those built by First Solar. SatCon is making a bet in that direction, adding staff and planning a production increase of 500 megawatts. The solar sector is ripe with landmines like Energy Conversion Devices (Nasdaq: ENER) in 2011, but inverters are a great way to invest in the sector without getting burned by one solar stock.

2. American Superconductor (Nasdaq: AMSC)
American Superconductor is a beaten-down stock on worries that Sinovel, its main customer, is running into oversupply in China. That's a valid concern for Sinovel and may be a reason it announced an IPO this week, but the customer base is just starting to build for American Superconductor. Doosan Heavy Industries just placed an order of more than $10 million, marking the seventh customer to place a volume order in the past 12 months. These Windtec products are driving results now, but SolarTie, D-Var, and superconductor wire could be future growth drivers in alternative energy.

3. AeroVironment (Nasdaq: AVAV)
AeroVironment makes the odd combination of unmanned aircraft systems and efficient electric energy technologies. A recent $46.2 million order from the U.S. military will help unmanned aircraft systems, but it's the charging stations I have my eye on. Nissan is working with AeroVironment on supplying home charging docks for new LEAF owners, and as more electric vehicles hit the road in the next few years, demand should remain strong. The charging market won't be without competition, but AeroVironment is well on its way to a market-leading position.

4. SmartHeat (Nasdaq: HEAT)
SmartHeat makes plate heat exchangers and technology helping to improve China's efficiency in burning coal. Its products have been so successful that it grew revenue 36% last quarter and saw net income increase 25.1%. We need to keep an eye on the increasing diluted share count, but operations are improving quickly.

Which alternative energy company are you betting on in 2011? Leave your pick in the comments section below.

Interested in reading more about SmartHeat? Click here to add it to My Watchlist, which will find all of our Foolish analysis on this stock.

Fool contributor Travis Hoium owns shares of AVAV and AMSC. You can follow Travis on Twitter at @FlushDrawFool, check out his personal stock holdings or follow his CAPS picks at TMFFlushDraw.

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