As more solar electricity lights up homes and businesses across the country, it also spotlights a growing, thorny issue: how do you recycle discarded solar panels safely? And should solar companies follow a set of sustainable practices similar to those in the electronics industry?

That debate could grow louder with the release of the latest Silicon Valley Toxics Coalition (SVTC) “solar scorecard” Tuesday. The scorecard, based on survey responses and publicly available information, ranks 37 solar manufacturers’ actions and commitments to practices such as reporting emissions, using water and energy efficiently, avoiding the use of conflict materials and promoting workers’ health and safety.

For companies that also develop and build solar power plants, the coalition looks at how they incorporate wildlife conservation into their projects.

“When the cleantech movement started, the solar industry had a lot of the similar environmental impacts as the microelectronics industry that the SVTC had looked into,” said Sheila Davis, executive director of the coalition. “We wanted to ensure that the solar industry is clean.”

The No 1 spot goes to Trina Solar, a Chinese company that received 92 out of 100 points. SunPower, based in Silicon Valley, grabbed the second spot with 88 points, followed by Yingli Green Energy (81), also a Chinese company. Germany-based SolarWorld (73) and REC (71), from Norway, complete the top five listings.

Eight companies, which include Suniva, Andalay Solar, Jinko Solar and Hyandai, scored below 10.

The 2014 scorecard is the fifth by the coalition, a nonprofit that works with investors who see sustainability as a criterion for deciding which companies to put their money in. The solar industry has grown quickly. The US market is expected to install 6.5 gigawatts of solar panels in 2014, which would be 6.5 times the installations in 2000, according to GTM Research. Globally, the solar market is set to build 50 gigawatts of solar panels, according to SolarBuzz. The 19.5 gigawatts that will likely be added in the fourth quarter alone would exceed what was installed in all of 2010.

“The scorecard is helpful for giving investors an independent view of the industry,” said Steven Heim, managing director and the director of environmental social governance research at Boston Common Asset Management. “We can then see if it raises questions or highlights companies that we might consider.”

Boston Common helps the coalition by sending out a letter – accompanying the survey – to urge company participation. It’s also the public face of the more than 25 institutional investors in North America and Europe that signed the letter. The investors collectively manage $1.6tn worth of assets, Heim said.

A solar panel is made up of solar cells and electronics for transporting the electricity produced. The most common material for solar cells is silicon, the same ingredient that’s in the chips that run computers and cell phones. The processes of turning silicon into cells involve the use of many gases, chemicals and metals and leave behind toxic wastes that pose health hazards for workers and the environment.

The coalition began to take interest in the solar industry’s environmental management after seeing the emergence of many silicon processing plants in late 2000s to meet the fast-growing demand. Many of these plants rose up in China, which also was home to manufacturers who went on to become the top solar cell and panel makers in the world and held initial public offerings on the New York Stock Exchange or the Nasdaq.

One of the high-profiled incidents of environmental mismanagement involved Jinko Solar and its discharge of toxic waste from its facility in China’s Zhejiang province into a river. The 2011 incident sparked a three-day protest from the villagers upset over the large number of dead fish in the river, brought out riot police and prompted the company to suspend its operation there.

Jinko said it unintentionally discharged “a small amount of solid waste” into the river and attributed heavy rains for causing a spill from waste containers outside of its warehouse.

The 37 companies on the 2014 scorecard represent about 75% of the manufacturing sector, the coalition said. Only seven manufacturers, which account for 25% of the sector, filled out the survey. The coalition then gathered more data from public records, such as company websites, regulatory filings and news stories. The survey response rate dropped from 34.6% in 2012 and 51.1% in 2012, reflecting in part of the high number of manufacturers that shrank significantly or went out of business in the past few years because supply exceeded demand.

Some low-scoring companies didn’t want to talk about the scorecard. A few explained why they didn’t respond to surveys. Hanwha SolarOne said in a statement that the company didn’t have time to respond to the survey and the score, 10 out of 100, “in no way an accurate measure of the sustainability of HSOL’s business”.

Andalay Solar, a penny stock, has been outsourcing the manufacturing work and struggling to survive, and that explains why it didn’t reply to the survey, said Wei-Tai Kwok, chief operating officer at Silicon Valley-based Andalay. The company is changing its business model to move away from selling solar panels and will focus on licensing its mounting system that props up solar panels instead.

Canadian Solar, which has a score of 14, said in a statement that the coalition was demanding too many details about the company’s business practices. The company said it refused to respond to the survey and contended that the score is inaccurate because the coalition “penalizes companies that did not participate in the SVTC survey”.

“To conclude, if the SVTC does not change their communication and ranking practices, we may seek legal action,” said the statement from Canadian Solar.

Davis said Canadian Solar’s statement is “unusual” and the information sought by the coalition is something that that would usually be included in a corporate social responsibility report.

“We’ve aggressively outreached to companies because we want solar companies to do well and for the solar industry to be an environmental leader,” Davis said.

The scoring weighted issues such as solar panel recycling, worker safety and emissions reporting. Recycling is a critical issue, according to the coalition, which would like to see the US solar industry fund a program that collects used panels for proper recycling.

The coalition is hoping that the Solar Energy Industries Association will take the lead in developing the recycling program and pressing its members to plan for and report their sustainable practices. The association seems slow in tackling the issue of recycling, let alone setting up a program, Davis said.

“We were told that they were going to release a report last year and [were] looking into the issue,” Davis said. “Up to this point we haven’t seen any action from them.”

The trade group said it is working on figuring out “the best next step for the industry on recycling.” said John Smirnow, vice presient of trade and competitiveness at the association. The association is looking at ways to provide incentives for building and running recycling centers and is keeping a close watch on California, which will likely be the first in the country with solar-specific recycling regulation, Smirnow said.

Smirnow said the trade group understands the need for its members to take sustainability issues seriously and launched the “Solar Industry Commitment and Environmental and Social Responsibility” in 2013. The document includes some broad sustainability issues that its signatories promise to address, such as reducing energy use, creating safe working environment and disposing of hazardous materials and other wastes properly.

Over two dozen companies have signed the document, including big-name manufacturers, such as Trina, Yingli and SunPower, Smirnow said.

After five years of ranking top global solar companies, the coalition now plans to create a sustainability standard – as well as a registry aimed at influencing the purchase decisions of solar energy equipment buyers, from installers to power plant developers – and convince solar companies to follow it.

The coalition is working with the Green Electronics Council to create the standard and registry, and is hoping to enlist solar companies as well. The Green Electronics Council runs a registry on electronics manufacturing.

“We have been encouraged by some of the companies that want to show that they are doing above and beyond what the regulations say,” said Dustin Mulvaney, the coalition’s science advisor and an assistant professor of environmental studies at San Jose State University. “I have a lot of faith in the solar industry.”

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