Siemens, the industrial giant from Germany, bought Solel, the grandaddy of solar thermal firms, for $418 million and it won't likely be the last one of these types of deals.

Solel focuses on trough systems, which gather heat from the sun in parabolic mirrors. The heat is then used to produce steam, which gets run through a generator to produce power. The Israeli-based company was one of the early solar thermal players and participated in erecting solar thermal plants in California's Mojave desert in the late 1980s and early '90s. In the past few years, Solel has been supplying components to solar thermal plants in Spain and working on getting approvals for U.S. projects. In the first six months of this year, the 500-employee company garnered $90 million in revenue.

The acquisition will further expand the reach of Siemens into greentech. The company in recent years has expanded its portfolio in water and energy efficiency. Siemens makes the turbines for solar thermal plants. Combined with Solel's experience in mirrors and building solar thermal fields, Siemens can now boast a nearly complete suite of technologies for power plants.

As the greentech market expands, large industrial conglomerates will likely continue to acquire companies. Startups and one-technology companies have the technology to improve the efficiency or reduce the cost of making biofuels or solar power. However, they don't have the money. Conglomerates have the capital and sales force required to take green ideas globally. Unfortunately, they sometimes lack the technology. Hence, the buying spree.

Siemens was selected as one of our top ten acquirers in greentech last month. Toshiba, TSMC, General Electric, Cisco Systems and Philips are also expected to make more acquisitions. Philips has already made two acquisitions this year in lighting.