Wednesday, 4 October 2017

Recycling solar panels and PVCu windows

Over the years I have installed PVCu¹ windows to save energy (but actually mainly just to be warm) and solar panels for renewable energy - what will happen when they get old and have to be replaced? The way that we deal with materials at end of life can make a significant difference to the overall carbon savings. For example both panels and windows contain glass and other materials that take a lot of energy in manufacture. If they are recycled properly and reduce emissions from building the next thing, then the overall carbon emissions can be significantly reduced. Does this happen?

There are two issues with recycling that are slightly related:
  1. What is possible? How much material can be reused or recycled and how much energy can be saved by doing so?
  2. Does it happen? Is there a recycling supply chain that actually picks up most of the waste generated?

It turns out that for windows and for solar panels high levels of recycling are achievable. However, whether this actually happens or not is another question.

Recycling window materials
Windows contain a lot of glass. This is a high energy material and recycling could save a lot of energy except that most recycled glass ends up ground up into aggregate - downcycling rather than recycling. The trouble with glass is that there are lots of different kinds and colours and it is difficult to make recycled glass to an exact spec and colour. Still at least it doesn't go into landfill.

PVCu windows also contain a lot of steel and aluminium. This is valuable and easy to recycle, once it has been separated.

They also contain PVCu, which for a long time was considered impossible to recycle. The best thing you could do was to burn it in an energy from waste plant. However, this is no longer the case: for example VEKA Recycling have invested in a process that makes new windows using 80% recycled PVC. They have a plant in Germany but they collect from the UK too and they accept post-consumer PVCu frames removed from homes and other buildings, regardless of where they were originally manufactured. I recommend the video here which shows how it works (scroll down towards the end of the page). The 80% limit is because they effectively wrap the old PVC in a thin layer of new PVC to make sure it has the right colour on the surface. (It's a shame this technique won't work for glass.)

Recycling solar panel materials
If solar panels have failed early in their life rather than due to gradual degradation they are often repairable and there is a global market for second hand solar panels. Apparently, the resale value is typically 70% of the original price [1].

However if they are not repairable then recycling is the next option. As with windows, solar panels contain a large quantity of glass, but the main interest for recycling is the metal content. They use small quantities of a range of metals, some rare, some valuable, and some of them hazardous or toxic. The most valuable is silver, for electrical contacts. In fact a significant part of the huge reduction in the cost of panels has been due to reducing the amount of silver needed. Ten years ago panels contained seven times as much as they do now. Still, as recently as 2014, nearly half the material costs of the panels were due to silver. Aluminium accounted for another 26% and silicon only 11% [1].

Separating the different components for recycling is quite complicated and, for silicon based panels, involves some high temperature processes. I recommend the flow diagram on the infographic here. Overall, around 85% of the mass of a panel can be recycled [1].

Collection of window waste
Living in the EU there are quite a lot of regulations about waste handling but these are different depending on the type of waste. Windows counts as construction waste for which the overall recycling target is 70% by weight[2]. Whether this is actually achieved is another matter.  In Cambridge, most construction waste probably ends up being sorted at the Amey plant at Waterbeach. They do say they separate glass, which goes to make aggregate. What happens to the rest is less clear [3].

Collection of solar panels waste.
Solar panels count as WEEE (Waste Electronic and Electrical Equipment) and the EU rules are more strict, in fact solar panels are a special class of WEEE. The target recycling rate is 85%. Also [producers] must inform buyers that the panels have to be disposed of in dedicated collection facilities and should not be mixed with general waste, and that takeback and recycling are free (European Parliament and Council, 2008b). They are also responsible for informing the buyer of their PV panel end-of-life procedures [1].

I confess I have no recollection of being told about this when we bought our panels in 2011 and I am quite sure I won't remember it in another 15 years time when I might consider that they are getting old and need replacing. I can only hope that when the time comes there will be suitable information available about what I need to do.

In fact there isn't much of a waste stream for PV panels as yet as most are not old enough to be thrown away.  The volume of waste is expected to be negligible until about 2030, but then increase rapidly. Given the regulations and the high value of the metals that can be recovered I have little doubt that the high rates of recycling will be achieved.

Re-duce, Re-use, Re-cycle
Reduce, Reuse, Recycle is the mantra, but what do we actually achieve? These two products show a range of benefits.
  • Reducing the amount of silver (and other stuff) in solar panels has helped reduce their cost and the resource needed to make them
  • Reusing solar panels that have been repaired enables developing countries to access solar technology more cheaply.
  • Recycling hazardous materials like silver, tin and lead in solar panels prevents them leaking into the environment.
  • Recycling high energy materials like PVCu and aluminium saves a huge amount of energy and hence carbon emissions (Recycled PVCu saves 75% of the energy needed for virgin. For aluminium the savings are more than 90% [4])
  • Downcycling glass into aggregate is better than putting them into landfill but is a wasted opportunity. The problem is that most uses of glass have strict specifications for composition and colour that are hard to match from recycled material. To improve recycling rates we need to be less fussy.

Actually achieving any sort of recycling seems to require regulation. It will not happen if left to the market until the materials needed are so rare and expensive that it becomes directly profitable. The EU has pretty good regulations, though they are not always strictly followed. Who knows what will happen when we leave the EU?

¹ PVCu is the new name for uPVC. Apparently we had to change the name to be consistent across the EU.

[1] End of life management Solar Photovoltaic Panels (IRENA) June 2016
[2] Construction and demolition waste ( June 2016
[3] Household recycling centres/waste transfer stations (Amey)
[4] Embodied Energy - the ICE database (circular ecology)

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