First Solar ( FSLR), the leader in the solar sector, said this month that it plans to build two new factories in the U.S. and Vietnam. Each plant will create 600 jobs.

Rival SunPower ( SPWRA) set up a manufacturing venture at a Flextronics ( FLEX) plant in Milpitas, Calif. There was much fanfare around the SunPower decision, but it's a small operation compared to SunPower's plants in Malaysia.

The disparity between the Solar Foundation's data and industry developments raises questions about the value of employer-supplied information in gauging growth in green jobs.

"That's the bad news, but this is not some vague study either. There were more than 2,400 employers providing detailed survey answers," said John Bunge, a statistics professor at Cornell University who developed the study methodology for the Solar Foundation.

The Bureau of Labor Statistics plans to have its green energy employment database running by 2012, and publish its first study of the job market by winter 2012, according to Rick Clayton, head of the BLS' division of administrative statistics and labor turnover.

"We're working rapidly to develop a definition and it's consumed most of this year. The first time through is always the roughest," the BLS economist said, adding that the green energy industry doesn't fit existing job descriptions neatly.

The BLS effort will do for green energy what it has done for every other sector of the economy -- and what an employer-based survey like the Solar Foundation's can't do. By tracking changes in the green job market, the agency will provide the discussion points for economists and investors. Until then, the effectiveness of government-backed green energy development as an engine for job growth remains a question.

-- Written by Eric Rosenbaum at TheStreet.

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