5 Research Priorities for Making Sure More Solar PV Materials Get Recycled

5 Research Priorities for Making Sure More Solar PV Materials Get Recycled

From the Article

by Jason Deign

Solar PV is now the dominant technology for new electricity generation capacity additions. That’s a huge achievement, but it brings up the vital question of what will happen to all those panels when they reach the end of their useful life.

In April, GTM reported on what was then unpublished research showing that solar panels can be landfilled without endangering human health. That’s good news, but landfills are hardly an ideal way to deal with solar industry waste. The cumulative mass of end-of-life PV modules is expected to hit 8 million metric tons globally by 2030, so improving recycling rates is an increasingly critical issue for the industry.

The main problem with recycling PV materials is that doing so costs more than dumping them in a landfill, says Garvin Heath, senior scientist at the National Renewable Energy Laboratory and co-author of the since-released study by the International Energy Agency’s Technology Collaboration Programme on Photovoltaics Power Systems.

“There’s only one crystalline silicon recycling facility in the world now, and that’s in France,” Heath told GTM.

To help remedy the situation, the recently published IEA paper on crystalline silicon PV recycling outlines five research recommendations for the solar industry.

1. Focus on getting the silicon back

The most expensive components of PV modules are the silicon wafers. They account for around half the cost of the module, and silicon accounts for the bulk of PV waste once the aluminum frames and glass covers are stripped off the module.

High-grade silicon is valuable, capable of fetching $100 per kilogram or more. But you can’t get that price for recycled silicon, for two reasons.

First, the mechanical crunching and smashing involved in recycling old modules add impurities to the silicon. And then there’s the fact that the silicon that’s used in new modules today is much purer than it was in modules made in the past. Even if you didn’t add any impurities through recycling, the output still wouldn’t be good enough for today’s solar manufacturers.

The first priority for PV recycling, then, is finding ways to improve the purity of the silicon that is recovered — without breaking the bank in the process.

2. Forget about trying to recover intact silicon wafers

If silicon wafers are so valuable, why not just recover the ones in old PV panels and reuse them? This sounds attractive but doesn’t work in practice for a number of reasons.

The main one is that few solar cells reach the end of their lives without developing cracks that impair performance. And the situation is getting worse because newer cells tend to be thinner and thus more prone to cracking.

On top of that, changes in cell efficiency, lifetime, silicon purity and form factor all mean that old wafers are unlikely to be of interest to today’s PV manufacturers.

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