How an Aussie invention could soon cut 5% of the world’s greenhouse gas emissions

Australian-designed technology will soon be responsible for 50% of all solar energy produced globally.
Glenn Hunt/AAP

Andrew Blakers, Australian National University

In the 1980s, a global race was underway: to find a more efficient way of converting energy from the sun into electricity.

Some 30 years ago, our research team at the University of New South Wales (UNSW) came up with a breakthrough, called the PERC silicon solar cell. The cells have become the most widely deployed electricity generation technology in terms of capacity added globally each year – comfortably exceeding wind, coal, gas, hydro and others.

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PERC stands for Passivated Emitter and Rear Cell. By the end of this year, PERC technology will be mitigating about 1% of global greenhouse gas emissions by displacing coal burning. Assuming that its rapid growth continues, it should be reducing greenhouse gas emissions by 5% by the mid-2020s and possibly much more in later years.

The terrible bushfires in Australia this summer, enhanced by the hottest and driest year on record in 2019, underline the need for urgent reductions in greenhouse gas emissions. By far the most effective way is driving coal out of electricity systems through very rapid deployment of solar and wind.

Soon, our Aussie invention will be generating half the world’s solar power. It is a pertinent reminder of Australia’s capacity for finding transformative technical solutions to address climate change. But we need the right government support.

A solar farm near Canberra.
Lukas Coch/AAP

An Aussie invention

Solar cells convert sunlight directly into electricity without moving parts. More efficient solar cells generally produce cheaper electricity because fewer solar cells, glass covers, transport, land and support structures are needed for a given solar power output.

By the early 1980s, the best laboratory cells around the world had reached 17% efficiency. This means that 17% of the sunlight was converted to electricity, and the rest (83%) of the solar energy was lost (as heat).

During the 1980s, our research team at UNSW led by Martin Green and myself created a series of world-record-efficient silicon solar cells. We reported 18% efficiency in 1984, 19% efficiency also in 1984, and the important milestone of 20% efficiency in 1986.

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In 1989 our group reported a new solar cell design called “PERC”, with a record efficiency of 22-23%.

This new, more efficient cell was better than the old ones because we eliminated some defects in the silicon crystal surface, which led to lower electronic losses. The PERC design also enabled us to capture the sunlight more effectively.

In the 1990s, further improvements to laboratory PERC cells were made at UNSW, leading to cells in the 24-25% efficiency range. The global silicon solar cell efficiency record remained at UNSW until recently.

There was a 25-year gap between development of the PERC cell and its rapid commercial adoption, which began in 2013. During this time, many people worked to adapt the PERC design to commercial production.

PERC cells are more efficient than previous commercial cells. Strong incentives for more efficient cells have recently arisen due to the continually falling share of cell costs as a proportion of total solar power system costs (including transport, land and mounting systems).

The big benefits of solar

Currently, solar power constitutes more than 40% of net new electricity generation capacity additions, with fossil, nuclear, wind, hydro and other renewables making up the balance.

Solar is growing faster than the other electricity generation technologies. Over time, as fossil-fuelled power stations are retired, solar (and wind) will dominate electricity production, with consequent large reductions in greenhouse gas emissions.

Solar power has experienced sustained rapid exponential growth over decades, while other generation technologies are currently experiencing static, falling or negligible sales.

This year, enough PERC solar modules will be sold to generate 60-70 gigawatts of power. According to projections, PERC will reach three quarters of annual solar module sales in the mid-2020s, enough to match the generation capacity additions from all other technologies combined.

About A$50 billion worth of PERC modules have been sold to date. This is expected to reach several hundred billion Australian dollars later this decade.

Just imagine

Australian emissions (excluding those from bushfires) are falling because we are installing solar and wind four times faster per capita than the EU, US, Japan and China.

Our position as a global leader in renewables installation is uncertain because the Renewable Energy Target, which was achieved in 2019, has not been extended.

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With supportive policy, such as facilitating more transmission to bring solar and wind power to the cities, Australia could greatly increase the speed at which wind and solar are deployed, yielding rapid and deep cuts at about zero-net cost.

Such policy would entail stronger and sustained government support for renewables deployment, and research and development of new technologies.

Renewables must replace polluting coal-fired power if the world is to tackle climate change.

Looking ahead

Solar energy is vast, ubiquitous and indefinitely sustainable. Simple calculations show that less than 1% of the world’s land area would be required to provide all of the world’s energy from solar power – much of it on building roofs, in deserts and floating on water bodies.

Solar systems use only very common materials (we could never run out), have minimal need for mining (about 1% of that needed for equivalent fossil or nuclear fuels), have minimal security and military risks (we will never go to war over solar access), cannot have significant accidents (unlike nuclear), and have minimal environmental impact over unlimited time scales.

Australia is making major contributions to mitigating climate change both through rapid deployment of wind and solar and technology development such as our PERC cells. But with better government support, much more can be done – quickly and at low cost.The Conversation

Andrew Blakers, Professor of Engineering, Australian National University

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

We can make roof tiles with built-in solar cells – now the challenge is to make them cheaper

This, except printed directly onto your roof tiles.
Cole Eaton Photography/Shutterstock

Md Abdul Alim, Western Sydney University; Ataur Rahman, Western Sydney University, and Zhong Tao, Western Sydney University

Despite being such a sunkissed country, Australia is still lagging behind in the race to embrace solar power. While solar panels adorn hundreds of thousands of rooftops throughout the nation, we have not yet seen the logical next step: buildings with solar photovoltaic cells as an integral part of their structure.

Our lab is hoping to change that. We have developed solar roof tiles with solar cells integrated on their surface using a specially customised adhesive. We are now testing how they perform in Australia’s harsh temperatures.

Our preliminary test results suggest that our solar roof tiles can generate 19% more electricity than conventional solar panels. This is because the tiles can absorb heat energy more effectively than solar panels, meaning that the tiles’ surface heats up more slowly in sustained sunshine, allowing the solar cells more time to work at lower temperatures.

The solar roof tile.

Australia’s greenhouse emissions continue to rise, making it harder to meet its commitments under the Paris agreement.

Globally, commercial and residential buildings account for about 40% of energy consumption. Other countries are therefore looking hard at reducing their greenhouse emissions by making buildings more energy-efficient. The European Union, for example, has pledged to make all large buildings carbon-neutral by 2050. Both Europe and the United States are working on constructing buildings from materials that can harness solar energy.

Here in Australia, buildings account for only about 20% of energy consumption, meaning that the overall emissions reductions on offer from improved efficiency are smaller.

That’s not to say that we shouldn’t go for it anyway, especially considering the amount of sunshine available. Yet compared with other nations, Australia is very much in its adolescence when it comes to solar-smart construction materials.

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Taking Australia’s temperature

In a recent review in the journal Solar Energy, we identified and discussed the issues that are obstructing the adoption of solar power-generating constructions – known as “building-integrated photovoltaics”, or BIPV – here in Australia.

According to the research we reviewed, much of the fear about adopting these technologies comes down to a simple lack of understanding. Among the factors we identified were: misconceptions about the upfront cost and payback time; lack of knowledge about the technology; anxiety about future changes to buildings’ microclimates; and even propaganda against climate change and renewable energy.

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Worldwide, BIPV systems account for just 2.5% of the solar photovoltaic market (and virtually zero in Australia). But this is forecast to rise to 13% globally by 2022.

Developing new BIPV technologies such as solar roof tiles and solar façades would not only cut greenhouse emissions but also open up huge potential for business and the economy.

According to a national survey (see the entry for Australia here), Australian homeowners are still much more comfortable with rooftop solar panels than other systems such as ground-mounted ones.

In our opinion it therefore stands to reason that if we want to boost BIPV systems in Australia, our solar roof tiles are the perfect place to start. Our tiles have a range of advantages, such as low maintenance, attractive look, easy replaceability, and no extra load on the roof compared with conventional roof-mounted solar arrays.

Challenges ahead

Nevertheless, the major challenges for this technology are the current high cost, poor consumer awareness, and lack of industrial-scale manufacturing process. We made our tiles with the help of a 3D printing facility at Western Sydney University, which can be attached to an existing tile manufacturing machine with minor modifications.

The current installation cost of commercial solar tiles could be as high as A$600 per square metre, including the inverter.

What’s more, we have little information on how the roof tiles will perform in long-term use, and no data on whether solar tiles will have an effect on conditions inside the building. It is possible that the tiles could increase the temperature inside, thus increasing the need for air conditioning.

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To answer these questions, we are carrying out a full life-cycle cost analysis of our solar tiles, as well as working on ways to bring down the cost. Our target is to reduce the cost to A$250 per square metre or even less, including the inverter. Prices like that would hopefully give Australian homeowners the power to put solar power into the fabric of their home.

The lead author thanks Professor Bijan Samali for valued supervision of his research.The Conversation

Md Abdul Alim, Postdoctoral researcher on sustainable development (Energy and Water), Western Sydney University; Ataur Rahman, Associate Professor, Western Sydney University, and Zhong Tao, Professor, Western Sydney University

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

New solar cells offer you the chance to print out solar panels and stick them on your roof

File 20180829 195313 1i0zj6w.jpg?ixlib=rb 1.1
This roof in Newcastle has become the first in Australia to be covered with specially printed solar cells.
University of Newcastle, Author provided

Paul Dastoor, University of Newcastle

Australia’s first commercial installation of printed solar cells, made using specialised semiconducting inks and printed using a conventional reel-to-reel printer, has been installed on a factory roof in Newcastle.

The 200 square metre array was installed in just one day by a team of five people. No other energy solution is as lightweight, as quick to manufacture, or as easy to install on this scale.

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Our research team manufactured the solar modules using standard printing techniques; in fact, the machine that we use typically makes wine labels. Each solar cell consists of several individual layers printed on top of each other, which are then connected in series to form a bank of cells. These cells are then connected in parallel to form a solar module.

Since 1996, we have progressed from making tiny, millimetre-sized solar cells to the first commercial installation. In the latest installation each module is ten metres long and sandwiched between two layers of recyclable plastic.

At the core of the technology are the specialised semiconducting polymer-based inks that we have developed. This group of materials has fundamentally altered our ability to build electronic devices; replacing hard, rigid, glass-like materials such as silicon with flexible inks and paints that can be printed or coated over vast areas at extremely low cost.

As a result, these modules cost less than A$10 per square metre when manufactured at scale. This means it would take only 2-3 years to become cost-competitive with other technologies, even at efficiencies of only 2-3%.

These printed solar modules could conceivably be installed onto any roof or structure using simple adhesive tape and connected to wires using simple press-studs. The new installation at Newcastle is an important milestone on the path towards commercialisation of the technology – we will spend the next six months testing its performance and durability before removing and recycling the materials.

The solar cells can be installed with little more than sticky tape.
University of Newcastle, Author provided

We think this technology has enormous potential. Obviously our technology is still at the trial stage, but our vision is a world in which every building in every city in every country has printed solar cells generating low-cost sustainable energy for everyone. This latest installation has brought the goal of solar roofs, walls and windows a step closer.

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Ultimately, we imagine that these solar cells could even benefit those people who don’t own or have access to roof space. People who live in apartment complexes, for example, could potentially sign up to a plan that lets them pay to access the power generated by cells installed by the building’s owner or body corporate, and need never necessarily “own” the infrastructure outright.

But in a fractured and uncertain energy policy landscape, this new technology is a clear illustration of the value of taking power into one’s own hands.The Conversation

Paul Dastoor, Professor, School of Mathematical and Physical Sciences, University of Newcastle

This article was originally published on The Conversation. 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.

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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.

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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.