Which of the world's largest solar PV makers are the most environmentally responsible? The Silicon Valley Toxics Coalition rates many of the manufacturers with the largest market share in the industry in the organization's latest Solar Scorecard.

German PV maker SolarWorld earned the best environmental grade of the 10 largest  manufacturers in the industry with a score of 91 out of possible 100 points for practices in four categories: recycling, green jobs, toxics and disclosure. Trina Solar, based in China, followed in second place with a score of 89. Tying for third place with scores of 87 were two firms among the top 10 largest, REC of Norway and First Solar of the U.S., and another U.S. firm, Abound Solar.

While the solar photovoltaic industry is growing, producing twice as many modules in 2010 than in 2009, mere growth isn't enough, according to the Silicon Valley Toxics Coalition. It's essential that the industry strives to be as green as the energy its technology produces, the organization says, because although generating electricity using solar PV systems doesn't produce greenhouse gases, the business of making the panels can have negative environmental and health impacts if manufacturers don't take steps to avoid them.

The Silicon Valley Toxics Coalition's Solar Scorecard, now in its second year, is aimed at improving PV makers' environmental practices by shedding light on their manufacturing processes.

There is "a limited window of opportunity to ensure that solar PV does not follow the electronics industry's toxic and unsustainable path," the organization says in its 2011 Solar Scorecard. "The Silicon Valley Toxics Coalition believes that we still have time to ensure that the PV sector is safe for the environment, workers and communities."

Disclosure is key to that effort, says Sheila Davis, the organization's executive director.

"It's very important that firms provide transparency," she said.

This year 15 PV manufacturing companies, including six of the 10 with the largest market share, responded to the organization's survey for the scorecard. In all 40 firms were queried and those responding represent 46.6 of the market share -- double the market share reflected in the first scorecard, Davis said.

Here is the list of scores:

SolarWorld, Germany - 91
Trina Solar, China - 89
Abound Solar, U.S.  - 87
First Solar, U.S. - 87
REC Solar - 87
SunPower, U.S. - 85
Solon, Germany - 84
Sovello, Germany - 83
Calyxo, Germany - 82
Yingli Solar, China - 72
SoloPower, U.S.  - 71
Motech Industries, Taiwan - 70
AXITEC, Germany - 64
Fluitecnik Group, Spain - 61
Eurener, Spain - 60

Other highlights from the scorecard include:

• 11 firms saying they would support a law requiring mandatory takeback and recycling. 
• 13 reporting that they audit and monitor their supply chain for environmental, health, and safety issues. 
• 14 reporting that they do not use prison labor.
• 3 -- SunPower, Eurener and AXITEC -- reporting that their products do not contain cadmium or lead.

The  Silicon Valley Toxics Coalition's 2011 Solar Scorecard is available at www.solarscorecard.com.

Image courtesy of SVTC.