Your solar electricity may not be as clean as you think.
Those shiny panels use the same technologies as are used in the wider electronics industry, which is known to have ethical and environmental problems both at the manufacturing stage and at the point of disposal.
But every year, the Silicon Valley Toxic Coalition produces a scorecard of how well manufacturers are performing in making their products safer and less polluting. They have just published their latest edition (see below).
Your solar energy may not be as clean as you think. The Silicon Valley Toxic Coalition has recently produced a new scorecard ranking manufacturers on safety, pollution and human rights. You can use it to help choose the best manufacturer. The top three suppliers for 2014 are Trina, Sunpower and Yingli.
The Solar Scorecard is based on SVTC's annual survey of photovoltaic (PV) module manufacturers, as well as on prior survey responses, interviews, news stories, and publicly available data.
The scorecard is intended to enhance transparency around environmental health, safety, and sustainability issues for communities, workers, and the environment. SVTC started collecting data for the Solar Scorecard in 2009 when the solar industry produced just 6.4 GW of PV modules. In 2013, the PV industry produced 38.7 GW, more than six times that amount, they calculate.
Company participation: Since 2010, 44.5% of the PV industry (based on 2013 market share) has participated in one or more SVTC survey. Seven companies representing 25.2% of the PV module market share responded to the 2014 SVTC survey, a decline from the response of 51.1% in 2012, due largely to the bankruptcies and/or restructuring of former participants. For the 2014 Solar Scorecard, SVTC scored a total of 37 companies based both on survey responses and on information available on company websites and from publicly available sources.
Pollution and greenhouse gas emissions
The problems identified by SVTC include the need for workers in plants making the panels to be protected from toxic exposure; and preventing hazardous e-waste dumping in developing countries like India, Ghana, and China, where the proper infrastructure protect workers or the environment is lacking.
A key report (Towards a Just and Sustainable Solar Energy Industry) published by SVTC in 2009 says that there may be no cause for alarm about their impact in countries with well regulated environmental pollution regimes, but such strict monitoring and controls are not necessarily in force everywhere.
Examples of toxic substances used in the manufacture of silicon cells and semiconductors are silane gas, used in the production of crystalline silicon (c-Si) cells. It is extremely explosive and presents a potential danger to workers and communities.
Accidental releases of the gas have been known to spontaneously explode, and the semiconductor industry reports several silane incidents every year. The production of silane and trichlorosilane results in waste silicon tetrachloride (SiCl4), an extremely toxic substance that reacts violently with water, causes skin burns, and is a respiratory, skin, and eye irritant. This will only be a problem in places with little or no environmental regulation.
Sometimes the extremely potent greenhouse gas sulfur hexafluoride (SF6) is used to clean the reactors used in silicon production. The Intergovernmental Panel of Climate Change (IPCC) considers this to be the most potent greenhouse gas per molecule; 25,000 times more potent than CO2. It is being phased out in most of the industry.
Other chemicals used in the production of crystalline silicon requiring special handling and disposal procedures include:
- sodium or potassium hydroxide (used to remove the sawing damage on the silicon wafer surfaces): dangerous to the eyes, lungs, and skin;
- hydrochloric acid, sulfuric acid, nitric acid, and hydrogen fluoride (used to remove impurities from and clean semiconductor materials);
- phosphine (PH3) or arsine (AsH3) gas (used in the doping of the semiconductor material): inadequate containment or accidental release poses occupational risks;
- phosphorous oxychloride;
- phosphorous trichloride;
- boron bromide and boron trichloride.
Other dangerous chemicals used in the manufacture of amorphous-Si include acetone, aluminum, chlorosilanes, diborane, phosphine, isopropanol, nitrogen, silicon tetrafluoride, tin, and, where germane is used, germanium and germanium tetrafluoride.
CdTe cells use cadmium, cadmium sulfide, cadmium chloride, and thiourea. Cadmium is a known carcinogen46 and is considered "extremely toxic" by the U.S. Environmental Protection Agency (EPA) and Occupational Safety and Health Administration (OSHA).
The Pesticide Action Network recognizes thiourea as a "Bad Actor Chemical" because it is a known carcinogen and can be toxic.
Numerous chemicals are used in the production of CIS and CIGS panels, many of them very toxic. These include hydrogen selenide (or selenium hydride, H2Se), which is considered highly toxic and dangerous at concentrations as low as 1 part per million in the air.
Extended Producer Responsibility shunned by USA
Extended Producer Responsibility (EPR) requires companies to take responsibility for the impacts of their products: from the materials used in manufacturing to product recycling.
One well-known form of EPR is producer take-back, which requires companies to take back their products when users are done with them and ensure that they are recycled safely and responsibly.
EPR policies provide incentives for companies to design and produce cleaner and more easily recyclable products, and discourage the practice of "planned obsolescence" (intentionally making products that quickly become out of date or useless).
Whereas most PV modules sold in Europe are covered by a prefunded Extended Producer Responsibility (EPR) scheme to ensure safe and responsible disposal, no PV modules in the USA do so.
Three PV manufacturers (Trina, Yingli, and Up Solar) have written to the Solar Energy Industries Association (SEIA) seeking action on EPR for PV modules in the USA. Over the past three SVTC surveys, 14 companies have said they would support public policy for an EPR scheme for PV modules.
The SVTC comment that "commercial, government, or residential purchasers of PV modules are making a long-term financial and environmental commitment, and PV module manufacturers should make the same long-term commitment to the nvironment and worker safety."
SVTC also seeks to stop the practice of sending e-waste to U.S. prisons for dismantling, which results in toxic exposure to inmates.
Good news
The good news is that emerging technologies for the generation of solar electricity are not likely to be so potentially toxic.
These include:
- Dye-sensitized solar cells, which utilise a pigment that effectively absorbs sunlight. The dye can be organic, of plant origin, like the colouring found in pokeberries or blackberries. When light falls onto the dye-sensitized solar cell, it is absorbed by the dye; and
- Organic (living or dead carbon-based) solar cells, made of biodegradable materials.
These are approaching commercially viable status.
David Thorpe is the author of