Efficient recovery justifies silver’s use in solar cells


Silver is a scarce raw material but the first real scale study of recycling polymer solar cells reveals that its use can be sustainable.

The organic photovoltaic life cycle

Putting up huge numbers of solar panels every day could help address the world’s energy crisis. ‘If you want to solve big problems, then the scale of whatever you are doing is also likely to be big, and so is any waste you generate,’ explains Frederik Krebs who led the study at the Technical University of Denmark. 'This should therefore be part of your thinking when you are developing something.'

Silver is needed for solar cell electrodes but it is also a precious metal, cutting into both the cost of production and energy payback time of mass-produced solar cells. Now, Krebs’ team has demonstrated that 95% of the silver electrodes in polymer solar cell modules can be reclaimed as silver chloride after simply shredding the modules and soaking them in nitric acid. This yield would diminish the overall energy payback time of the solar cells from 139 days to 128 days, a decrease of 8%.

To decommission the solar cells they are rolled up (left) then shredded (right)

Experts in sustainable energy have praised the study. ‘Research like this, that sits between the basic science of organic photovoltaics and the commercial deployment of solar modules, is exceedingly important, as it informs chemists and physicists of the real-world constraints and challenges that underly the societal relevance of their research,’ says Ryan Chiechi at the University of Groningen in the Netherlands.

Annick Anctil, of Clemson University in the US, says that life-cycle assessment at an early stage will help ensure scientists are developing sustainable forms of energy and not creating new issues, 'such as an electronic waste problem in the case of organic photovoltaics.’

‘Unlike the environmental failures seen in the geriatric fossil fuel industry, the photovoltaic industry is solving potential problems before they occur,’ adds Joshua Pearce of Michigan Technological University in Houghton, US. ‘With this kind of progress, the potential for a low-cost, solar-powered future looks pretty bright.’


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