Siemens is the company that just can't resist.

The German industrial giant is considering purchasing solar cell maker Q-Cells, according to Reuters (via Forbes here.).

Earlier this month, Siemens bought solar thermal vendor Solel for $418 million. Earlier, it has bought an number of water companies and ramped up its investments in smart grid.

In a list of the top ten acquirers in greentech, we picked Siemens as number two, right behind General Electric.

This is a pattern you should get used to. Small, innovative startups often have tremendous technology, but they lack the capital, distribution networks and relationships to bring their ideas to fruition. Large conglomerates often fail to capitalize on the interesting stuff in their labs, but they do know how to buy stuff that seems to work and take it commercial. Thus, greentech will be a barbell market – a lot of small companies and a few large companies with not a lot of things in between.

As acquisitions spread, you can start to think of Silicon Valley as a farm system for conglomerates. That doesn't sit well with some: Didn't Silicon Valley win out over old-style conglomerates like Digital and IBM? Yes, but it doesn't mean it happens in every situation. Green startups are born to be bought.

And if Siemens isn't interested, start talking to Philips (two lighting acquisitions this year), Toshiba, TSMC, and Cisco Systems.