There are rumblings and grumblings floating around that the renewable energy industry will start consolidating in the coming year. While that speculation's nothing new, the solid footing some firms now find themselves on leaves plenty of opportunities for aggressive acquisitions.

Do wind and sun mix?
Last week, a rumor that Trina Solar (NYSE: TSL) might be interested in European wind turbine manufacturer Gamesa piqued my interest. Wind and solar don't exactly provide economies of scale on a manufacturing level, but they do serve the same market and some of the same buyers. Gamesa is also in the project-development business, which could give Trina development capabilities similar to those added by First Solar (Nasdaq: FSLR) and SunPower (Nasdaq: SPWRA).

Gamesa's stock is down 60% this year, which initially sparked speculation that a buyer might be looming. Gamesa's market cap of $1.73 billion might be on the hefty side for Trina, but with $685 million in cash on hand at the end of the second quarter, it isn't beyond the latter company's reach.

Thin film consolidation
There could also be moves this year in the thin film market, which is full of many small startups and only a couple of big manufacturers. I will be surprised if First Solar doesn't take action to expand its technology next year. The thin-film manufacturer still dominates solar in cost leadership, but it's running out of costs to cut, its and CdTe technology might be reaching the limits of its efficiency. First Solar has a small R&D lab testing the CIGS technology right now, but I would like to see a big move to expand its technology options. It can't really think it will be leading solar in five years with CdTe panels, can it?

Most thin film manufacturers are still private companies controlled by venture capital. To these backers, a buyout offer from First Solar could be an attractive way out.

Elsewhere in China...
Yingli Green Energy
(NYSE: YGE) would also be a logical buyer if the industry begins to consolidate. Yingli had $577 million of cash at the end of last quarter, and it's one of the more ambitious solar players right now.

Whatever happens, we're in for an exciting 2011 for solar.

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Fool contributor Travis Hoium owns shares of First Solar and SunPower. You can follow Travis on Twitter at @FlushDrawFool, check out his personal stock holdings, or follow his CAPS picks at TMFFlushDraw. 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 has a disclosure policy.