The debate over the toxic potential of thin film solar panels based on cadmium compounds has been reignited.
Cadmium Telluride (CdTe) is a commonly used material in thin film solar modules. Cadmium is a heavy metal and extremely dangerous. Cadmium fumes may cause flu like symptoms and more severe respiratory problems. Cadmium dust is even more toxic, leading to respiratory, liver and kidney problems that can be fatal. Some compounds containing cadmium are thought to be carcinogenic.
Cadmium telluride, while considered less dangerous in relation to acute exposure, is toxic if ingested, improperly handled or the dust inhaled.
In relation to solar panels, the CdTe is safe while encapsulated in the module, but if the panel is damaged and exposed to water, the cadmium telluride could leach into the water. Aside from this contaminated water entering the wider environment through stormwater runoff, this issue raises concerns particularly where rainwater is harvested from a rooftop for use within the building.
In an interview on CleanEnergyAuthority, Vice President of Technology for solar panel manufacturer REC, Trond Westgaard, said since cadmium telluride based panels are not officially considered a dangerous product, there is also a risk of them being mixed with other waste after being damaged or at the end of their serviceable life.
While even silicon based solar panels have their own problematic element – lead – Mr. Westgaard says tests have shown lead leaching potential of approximately 4 grams of lead per kilowatt installed compared to approximately 23 grams of cadmium per kilowatt installed for CdTe panels. Additionally, he said cadmium is considered 10 times more hazardous than lead.
Mr. Westgaard acknowledges the handling of CdTe panels in large solar farms may be closely monitored and recycling programs in place, but states REC is concerned with home solar power and medium scale solar installations that may not be subject to such controls. REC does not use cadmium telluride in any of its solar panels.
Earlier this year, Australian solar power solutions provider Energy Matters expressed similar concerns about cadmium panels, stating that while the company is open to the idea of offering CdTe based thin film solar panels at some point and have discussed their concerns with manufacturers, the issues of safety have not yet been addressed to their satisfaction.