Another Study of PV Recycling

Solar energy is a wonderful technology, cleanly and silently harvesting the abundance of our star.  It’s absolutely magical—free sunlight turns to electricity. 

But solar power is real, and in the real world even magic has its costs.

The booming success of solar energy has seen the installation of thousands of PV panels in the last decade, increasing the number of systems manyfold.

In two to three decades all the existing systems will wear out and need to be decommissioned or replaced.  What will happen to the obsolete PV panels?   We would like to see decomissioned PV panels recycled, and useful materials reused?  Unfortunately, PV panels are a form of electronic waste, and many contain toxic materials.  PV panels can be recycled, but it requires specialized processes.

Trailing in the wake of the massive build up of PV installations, a recycling industry is just beginning.  The question is, what will happen as the current bumper crop of PV installations reaches the end of life?  What kind of recycling and reuse will be available, and how effective will it be.

Current technological developments will enable recycling, which is necessary.  But the technology alone is not sufficient, there must be a political economic system to enable, sustain, and, where necessary, mandate recycling.

This summer researchers from NREL report a study of “social factors” in developing this circular economy [1].  The study computer models that explore the behavior of the key stakeholders, “PV owners, installers, recyclers and manufacturers”, and the key activities in end of life, “repair, reuse, recycling, landfilling and storage.”

In the research model the multiple stakeholders are affected by their own economics, and their decisions affect both the outcomes and economics of other stakeholders.  Changes to rules constrain or encourage decisions that shift costs among stakeholder, change the most likely paths taken, and change the outcomes.

In some jurisdictions, notably the EU, the paths are legally confined (e.g., landfilling is not allowed), and others, notably the huge US market, is unconstrained except by general economics.  Under the baseline US rules (i.e., no rules), the vast majority of PV panels  are and will continue to be landfilled, few panels will be reused,and less than 10% of the materials will be recovered.

The reason for this is simple.  The cost of recycling falls upon the last owner who is decommissioning the panels, but did not necessarily install them or receive any benefit.  Used PV panels are not especially valuable, and the cost of recycling is very high and may be inconvenient; so last owners are likely to pick the simple and cheap option of dumping.

The researchers investigate “interventions”, including technical, infrastructure, and “social” improvments.  The latter include attitudes among the stakeholders, learning, landfill costs, and recycling costs.  Their model suggests that the “social” factors are far and away the most important, dwarfing the availability and technical capabilities. 

In the case of reusing PV modules, attitudes toward used equipment are critical.  And above all, the cost of recycling and landfilling dominate the results.

The researchers note that storage (rather than landfilling) can play a useful role as a “buffer”, holding materials until technology and economics arise to make recycling economical. 

But the most critical factor is to bring the cost of recycling down.  They find that a period of subsidies for recycling could be very important (to prime the pump for a recycling industry).

Of course, mandating and subsidizing recycling and/or banning or taxing landfilling would have the most dramatic effect.

John Fitzgerald Weaver elaborates on the effects of a relatively small tax on new PV systems that subsidizes recycling for older systems [2]. This kind of scheme would effectively reduce the cost of recycling to compete with landfilling.

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1. Julien Walzberg, Alberta Carpenter, and Garvin A. Heath, Role of the social factors in success of solar photovoltaic reuse and recycle programmes. Nature Energy, 6 (9):913-924, 2021/09/01 2021. https://doi.org/10.1038/s41560-021-00888-5
2. John Fitzgerald Weaver, Recycling solar panels: Making the numbers work, in PV Magazine, September 21, 2021. https://pv-magazine-usa.com/2021/09/21/recycling-solar-panels-making-the-numbers-work/