The growth in solar energy over the past decade has been nothing short of phenomenal. Global solar installations are expected to surpass 64 GW this year, smashing last year’s record and bringing total installed solar capacity to an expected cumulative total of over 310 GW by the end of the year. Last year, solar passed the 1 percent mark for percentage of energy produced globally, and we can expect it to continue to claim an ever greater share — especially as India, China and other developing nations ramp up their solar capacity.
Solar’s rise in demand is, of course, cause for celebration amongst those concerned with environmental issues. With an embodied energy payback estimated at approximately two years, a rooftop PV array truly does provide clean, renewable energy throughout the vast majority of its expected 20-30 year life span.
Even though 25 years is long enough to make investors happy, in environmental terms, it’s a very short period of time. Despite the fact that many solar energy systems installed in the ’70s and ’80s are still in operation, the truth is, every solar panel will eventually reach the end of its useful life span.
Facing the Dark Side of Solar
Carbon in the atmosphere may be the most prevalent environmental issue of the day, but it’s hardly the only one. The burgeoning number of solar panels being installed today will eventually end up in the waste stream: e-waste on a truly grand scale.
Simply landfilling spent solar panels is clearly not an option. In addition to taking valuable landfill space, many PV panels contain heavy metals, such as cadmium and lead. These substances can potentially be released into the environment through landfill leachate and/or open burning; and contaminate soil, water and/or air. Some solar panels also contain rare elements, such as gallium and indium. Their loss through indiscriminate solar panel disposal could result in permanent depletion of these substances in the future.
The solution, of course, is to recycle the panels.
The Challenges of Solar Panel Recycling
Solar panel recycling is no easy task, because the units are assembled from multiple, extremely different materials. These include:
- Glass (comprising the front cover of most PV panels)
- Aluminum (frame)
- Synthetic materials used to encapsulate and seal in the silicon cells — these may include such substances as ethylene-vinyl acetate (EVA), polyvinyl butyral (PVB) and/or polyvinyl fluoride)
- Silicon solar cells
- Metals such as lead, copper, gallium and cadmium
Proper recycling of solar panels demands that these disparate materials be separated and recovered with minimal damage and loss of material. The materials can then be re-used to manufacture new panels, or for other industrial applications. For instance, glass panel fronts can be ground and used in the manufacture of insulation and other products. Even the silicon cells themselves can often be recovered and re-etched to be used again. This is significant, because the creation of new silicon cells is an energy-intensive process.
Fortunately, advanced solar panel recycling is technology that is currently well within our grasp. The European solar panel recycling association PV Cycle has developed a process by which over 95 percent of a panel’s materials can be recovered. Certain solar panel manufacturers have also developed programs to accept used panels back for recycling.
Cooperation Is the Ticket
So far, the demand for solar panel recycling is still very small. Some manufacturers report that the vast majority of panels they process for recycling are ones that were damaged or defective. However, it is never too early to plan for the inevitable rise in the need for solar panel recycling as today’s installations reach the end of their useful life span.
Current approaches to the issue differ depending on geography. In Europe, solar panel disposal falls under the European Union’s Waste of electrical and electronic equipment (WEEE) directive and is strictly regulated. No such universal regulation exists yet in the U.S. at the federal level, except for the minority of panels that fail the Toxicity Characteristic Leaching Procedure (TCLP test) and thus are subject to the Resource Conservation and Recovery Act (RCRA). However, California has already enacted legislation governing solar panel disposal, and it’s likely that other states will follow suit in the future.
Like all end-of-life-cycle disposal challenges, this one is best approached as a joint effort between manufacturer, supplier, consumer and regulating bodies. Working together, we can help ensure that solar remains a clean, healthy energy solution from cradle to grave.
Lead image credit: Darin Dingler | Flickr