There’s a looming waste crisis from Australia’s solar energy boom

Rooftop solar has boomed, but soalr panels only last about 20 years. What happens to the waste?
Flickr, CC BY-SA

Rodney Stewart, Griffith University; Hengky Salim, Griffith University, and Oz Sahin, Griffith University

As Australians seek to control rising energy costs and tackle the damaging impacts of climate change, rooftop solar has boomed.

To manage the variability of rooftop solar – broadly, the “no power at night” problem – we will also see a rapid increase in battery storage.

The question is: what will happen to these panels and batteries once they reach the end of their life?

If not addressed, ageing solar panels and batteries will create a mountain of hazardous waste for Australia over the coming decades.

Our research, published recently in the Journal of Cleaner Production, looked at the barriers to managing solar panel waste, and how to improve it.

A potentially toxic problem

Solar panels generally last about 20 years. And lead-acid and lithium-ion batteries, which will be the most common battery storage for solar, last between five and 15 years. Many solar panels have already been retired, but battery waste will start to emerge more significantly in 2025. By 2050 the projected amount of waste from retired solar panels in Australia is over 1,500 kilotonnes (kT).

Mass of end of life solar panels (a) and battery energy storage (b) 2020-2050.
Salim et al. 2019

Solar panels and batteries contain valuable materials such as metals, glass, ruthenium, indium, tellurium, lead and lithium.

Recycling this waste will prevent environmental and human health problems, and save valuable resources for future use.

Product stewardship

Australia has a Product Stewardship Act, which aims to establish a system of shared responsibility for those who make, sell and use a product to ensure that product does not end up harming the environment or people at the end of its life.

In 2016, solar photovoltaic (PV) systems were added to a priority list to be considered for a scheme design. This includes an assessment of voluntary, co-regulatory and regulatory pathways to manage the waste streams.

Sustainability Victoria (on behalf of the Victorian state government and with the support of states and territories) is leading a national investigation into a system of shared responsibility for end-of-life solar photovoltaic systems in Australia. Our research project has supported the assessment process.

Industries play a crucial role in the success of any product stewardship scheme. As we move into assessing and testing possible schemes, Australia’s PV sector (and other stakeholders) will have critical input.

A preferred product scope and stewardship approach will be presented to environment ministers. Scheme design and implementation activities are tentatively set to start in 2020.

Moving towards a circular economy

Federal and state environment ministers recently agreed to update the National Waste Policy to incorporate the principles of a circular economy.

This approach aims to reduce the need for virgin raw materials, extend product life, maintain material quality at the highest level, prioritise reuse, and use renewable energy throughout the process.

Read more:
Explainer: what is the circular economy?

Businesses in Australia currently have little incentive to innovate and improve the recycling rate. By helping implement circular business models such as lease, refurbishment and product-service systems, we can boost recycling, reduce collection costs and prolong tech lifetimes.

Requiring system manufacturers, importers or distributors to source solar panels and batteries designed for the environment makes both economic and environmental sense. By doing so, recyclers will recover more materials and achieve higher recirculation of recovered resources.

Consumers need to be provided with proper guidance and education for responsible end-of-life management of solar panels and batteries.

Immature domestic recycling capability

Now that China is no longer accepting waste for recycling, Australia needs to rapidly develop its domestic recycling industry. This will also spur job creation and contribute to the green economy.

Given Australia is struggling to recycle simple waste, such as cardboard and plastics, in a cost-effective way, we need to question our capability to deal with more complex solar PV and battery waste.

Australia currently has little capacity to recycle both solar panels and batteries.

And even if China were to suddenly start accepting Australia’s waste – an unlikely proposition – we cannot simply export our problem. As a signatory to the Basel Convention, exporting hazardous materials requires permits.

A previous study suggests half of Australia’s scrap metal is exported for overseas processing, which indicates the lack of incentives for domestic recycling.

Even if we build domestic recycling capability for solar panels and batteries, it will be underused while landfills remain available as a low-cost disposal option.

It’s promising that South Australia and the ACT have banned certain e-waste categories from entering landfill, while Victoria will implement an all-encompassing e-waste landfill ban from July 1 2019. This means any end-of-life electrical or electronic device that requires an electromagnetic current to operate must be recycled.

Creating a circular economy for solar and battery waste will need a strong commitment from policymakers and industry. Ideally, we need to prioritise reuse and refurbishment before recycling.

If we combine sensible policies with proactive business strategy and education to promote recycling rates, we can have a reliable and truly sustainable source of renewable energy in this country.

The authors would like to acknowledge the contribution of Michael Dudley from Sustainability Victoria to this article.The Conversation

Rodney Stewart, Professor, Griffith School of Engineering, Griffith University; Hengky Salim, PhD Candidate, Griffith University, and Oz Sahin, Senior Research Fellow, Griffith University

This article is republished from The Conversation under a Creative Commons license. Read the original article.


Semitransparent solar cells: a window to the future?

File 20180215 124886 1cij0t2.jpg?ixlib=rb 1.1
Looking through semitransparent cells – one day these could be big enough to make windows.
UNSW, Author provided

Matthew Wright, UNSW and Mushfika Baishakhi Upama, UNSW

Can you see a window as you are reading this article?

Windows have been ubiquitous in society for centuries, filling our homes and workplaces with natural light. But what if they could also generate electricity? What if your humble window could help charge your phone, or boil your kettle?

With between 5 billion and 7 billion square metres of glass surface in the United States alone, solar windows would offer a great way to harness the Sun’s energy. Our research represents a step toward this goal, by showing how to make solar panels that still let through enough light to function as a window.

Read more:
Solar is now the most popular form of new electricity generation worldwide

The economics of renewable energy are becoming increasingly favourable. In Australia, and many other parts of the world, silicon solar cells already dominate the rooftop market.
Rooftop solar power offers an increasingly cheap and efficient way to generate electricity.

But while great for roofs, these silicon modules are opaque and bulky. To design a solar cell suitable for windows, we have to think outside the box.

When we put a solar panel on a roof, we want it to absorb as much sunlight as possible, so that it can generate the maximum amount of power. For a window, there is inevitably a trade-off between absorbing light to turn into electricity, and transmitting light so we can still see through the window.

When thinking about a cell that could be fitted to a window, one of the key parameters is known as the average visible transmittance (AVT). This is the percentage of visible light (as opposed to other wavelengths, like infrared or ultraviolet) hitting the window that travels through it and emerges on the other side.

Semitransparent solar cells convert some sunlight into electricity, while also allowing some light to pass through.
Author provided

Of course we don’t want the solar window to absorb so much light that we can longer see out of it. Nor do we want it to let so much light through that it hardly generates any solar power. So scientists have been trying to find a happy medium between high electrical efficiency and a high AVT.

A matter of voltage

An AVT of 25% is generally considered a benchmark for solar windows. But letting a quarter of the light travel through the solar cell makes it hard to generate a lot of current, which is why the efficiency of semitransparent cells has so far been low.

But note that electrical power depends on two factors: current and voltage. In our recent research, we decided to focus on upping the voltage. We carefully selected new organic absorber materials that have been shown to produce high voltage in non-transparent cells.

When placed in a semitransparent solar cell, the voltage was also high, as it was not significantly lowered by the large amount of transmitted light. And so, although the current was lowered, compared to opaque cells, the higher voltage allowed us to achieve a higher efficiency than previous semitransparent cells.

Having got this far, the key question is: what would windows look like if they were made of our new semitransparent cells?

Do you see what I see?

If your friend is wearing a red shirt, when you view them through a window, their shirt should appear red. That seems obvious, as it will definitely be the case for a glass window.

But because semitransparent solar cells absorb some of the light we see in the visible spectrum, we need to think more carefully about this colour-rendering property. We can measure how well the cell can accurately present an image by calculating what’s called the colour rendering index, or CRI. Our investigation showed that changing the thickness of the absorbing layer can not only affect the electrical power the cell can produce, but also changes its ability to depict colours accurately.

A different prospective approach, which can lead to excellent CRIs, is to replace the organic absorber material with one that absorbs energy from the sun outside the visible range. This means the cell will appear as normal glass to the human eye, as the solar conversion is happening in the infrared range.

However, this places limitations on the efficiency the cells can achieve as it severely limits the amount of power from the sun that can be converted to electricity.

What next?

So far we have created our cells only at a small, prototype scale. There are still several hurdles in the way before we can make large, efficient solar windows. In particular, the transparent electrodes used to collect charge from these cells can be brittle and contain rare elements, such as indium.

Read more:
Solar power alone won’t solve energy or climate needs

If science can solve these issues, the large-scale deployment of solar-powered windows could help to bolster the amount of electricity being produced by renewable technologies.

The ConversationSo while solar windows are not yet in full view, we are getting close enough to glimpse them.

Matthew Wright, Postdoctoral Researcher in Photovoltaic Engineering, UNSW and Mushfika Baishakhi Upama, PhD student [Photovoltaics & Renewable Energy Engineering], UNSW

This article was originally published on The Conversation. Read the original article.