Recycling Solar PV Panels

Ashes to Ashes, Dust to Dust. A very proverbial saying, but this rarely applies to materials we extract from earth. Silicon-dioxide (silica/quartz/sand) used in semiconductors, inverters and other industries are often not recycled. Solar photovoltaic (PV) panels are also made from such silicon wafers sandwiched between a glass and plastic back sheet (with tin, lead and silver connections) duly held by an aluminum frame. A small copper wired junction box sits underneath. Due to its falling cost and ease of installation, solar PV now proliferates the globe but they are also on the verge of creating their own e-waste problem. Right now, the world does not have a cost-effective plan to deal with solar PV panels after their useful life.

The International Renewable Energy Agency (IRENA) projects that by 2050, about 78 million metric tons of solar panels will see their end of useful life and generating thereafter about 6 million tons of PV e-waste annually. The initial solar PV installation (of early 2000) is now approaching its end of useful life. While this may be a small amount today, but going forward this waste volume will increase exponentially with each passing decade (commensurate with increasing deployment). There are arguments being made that the PV e-waste is (and will be) a small fraction of the cumulative total solar PV panels manufactured/installed and an even smaller percentage relative to the total electronic e-waste. But a counter argument would be that this is still substantial and points to a growing e-waste problem. Add to this the panels that get damaged due to storms and future replacements with more efficient panels, and this number will progressively grow faster. If nothing is done to recycle it, most of these PV panels will go to landfill.

In a recent article for the WIRED (www.wired.com) that originally appeared on Grist (www.grist.org), written by Maddie Stone, titled “Solar Panels are Starting to Die, Leaving Behind Toxic Trash”, a good insight is presented on the current state of the PV recycling industry (or lack thereof). While several countries in EU have mandated such recycling efforts, most other countries including the United States, India and China have no such national initiatives. The article points to a recovered value of $3 per PV panel recycled against a recycling cost of $12-$25 (including transportation) in the USA, while land-filling just costs about $1 per panel. Another reference in the article states that the “recovery cost far exceeds the recycling revenue by almost 10-1 ratio”. The article concludes that better attempts/efforts should be made to use modern processes to achieve 95% of recapture and prevent these old PV panels from going to landfill. If 95% of the semiconductor material can be recovered and put back in the new PV panel (and repeated), the original silicon material could stay in a productive PV use lasting 1,200 years.

Arup, a global organization (www.arup.com ) recently published a white paper titled “Circular Photovoltaics – Business Models for Australia’s PV industry”, where the issues of PV e-waste is examined in detail and recommendations made. While the data analyzed is for Australia, it has several relevant learnings for the global market. Gleanings from this report include (1) Australia’s PV e-waste could reach between 300,000 to 450,000 tons by 2040; (2) it needs to establish an extended producer responsibility to address end of life; (3) standardized panel designs with a view towards recycling is needed; and (4) development of a circular economy strategy. The paper further adds that the potential recycle value of typical panel is almost “inverse” of its composition elements by weight. For example, PV panel glass is 70% by weight but recycle value is 8% of the total panel. Similarly, the aluminum frame is 18% by weight (26% recycle value). Silver which is a mere 0.06% by weight, has a recycle value of 47%, while the silicon cell at 3.65% has a value of 11%.

First Solar (a PV global giant) states that it has initiated efforts to recycle their own PV panels in the USA, Germany and Malaysia, using custom technology to disassemble/recycle their old panels, thereby recovering 90% of the materials. Other global examples of third-party PV recycling efforts include Veolia/France and SMaRT Center at the University of New South Wales/Australia. The SmaRT@UNSW recycling process is unique and attempts to eliminate unnecessary transportation costs (to central recycling depots), by creating affordable distributed “micro-factories” near consumption points (hence convenient and accessible). 

In a recent “World Solar Technology Summit” attended online by over 26,000 from 149 countries, presented its vision as to how the solar e-waste crises could be solved. Its rationale lay in not only cheaper cell manufacturing but a more sustainable technology that would achieve the following:

1.    Breakthrough processes that would see the current 45% wastage in silicon cell production to just 5%

2.    Process improvement towards a higher “champion efficiency” rather than today’s “average efficiency”

3.    New cell technologies leading to better longevity with no loss of efficiency (resulting in a lower LCOE)

4.    Breakthroughs in perovskite solar cells (PSC) that will need less cell materials for the same power output 

Notwithstanding all of the above, I think we are at the same crossroads (as many other industries before) that had similar viewpoints on end-of-life (i.e. computers, cellphones, packaging, appliances) but nothing substantial has happened in its recycling. Except for EU where some appliances are “returned” to the manufacturer after their end-of-life, most countries still have no mandated recycling strategy. With no policy intervention, this problem has been left to viable market forces that may emerge at some point in the future. Till then, it is land-fill.

I think the question for the PV industry, is not just focusing on the business model of driving production costs lower, but rather if better business models could make the PV technology have a higher “terminal value” at end-of-life, by either prolonging field life and/or allowing for a re-purposed useful-life. It is possible to work along these lines with mandated country policies to reduce ever-increasing e-waste. A few thoughts below:

1.    Standardize panel designs towards a view to easier recycling. For example, currently the glass (70%) tends to “contaminate” the recycling efforts with “impure crushed glass”.

2.    Promote PV panel lease rather than sale. This adds producer responsibility. Such a step will allow manufacturers to build better panels (albeit at a higher cost) but yielding better long-term benefits such as (a) longer useful life beyond 25 years; (b) better weather-resistant designs; and (c) a better opportunity to redirect older products to other projects.

3.    Offering high-ambient temperature rated PV panels. Most PV panels today are deployed in hot tropical climates (40-deg C ambient) and this is a growth segment. Derating panels from the 25 deg C standard test data often leads to erroneous design application and hence premature field failures.

 With no policy intervention, the PV e-waste will add to the existing cell-phone/PC e-waste heap (likely followed by lithium-battery e-waste).