Jinko Solar has won its fifth All Quality Matters Award for PV Module Energy Yield Simulation (Mono Group) at the Solar Congress 2019 organized by TÜV Rheinland.
Evaluation of energy yield simulation is based on performance testing of samples randomly selected from mass production under global conditions that range from irradiance of 100-1100W/m2 and temperatures of 15-75°C.
JinkoSolar ranked first in testing conducted for the mono group and was recognized for outstanding energy yield and its high quality standards.
Solar panel quality is the key to ensure the real electricity output in the field and secure PV project investment, the company said in a statement. A low-quality solar panel will meet a series of module failures like micro-cracks caused by the vibration during transportation, and backsheet failures caused by ambient humidity or ultra-violet radiation, reducing power output.
Independent third party DNV GL performs ageing tests at a more stringent standard than the IEC certificate, in order to highlight the ultimate reliability performance under the extreme outdoor conditions.
Jinko Solar has been the top performer for four consecutive years since 2014.
Energy Stuff specialises in Residential Solar with emphasis on Repairs, Replacements and upgrades. We also provide new systems, battery storage, Small Commercial, Off-Grid systems and smart monitoring systems. Energy Stuff only uses CEC accredited installers and we fully comply with the Victorian Govt. Solar Rebate Program.
Australian rooftops added a record of almost 500 megawatts of new solar photovoltaic capacity in the March quarter, as Victoria’s incentive scheme stoked a 90 per cent increase in that state’s installations.
record of almost 500 megawatts of new solar photovoltaic capacity in the March quarter, as Victoria’s incentive scheme stoked a 90 per cent increase in that state’s installations.
Data gathered by Green Energy Markets show the sector added about 45 per cent more capacity of solar PV – in systems of 100 kilowatts or smaller in size – compared with the January-March period a year earlier.
“It’s usually a little bit slow in January and February but [previous records] have really been blown away,” said Tristan Edis, director of analysis at Green Energy Markets, a consultancy firm.
The first-quarter installations of about 482MW were led by Victoria, where the Daniel Andrews government’s $2250 rebate per unit helped propel that state above sunnier neighbours Queensland and NSW.
Green Energy Markets expects solar PV capacity on rooftop will top 2000MW this year, or about a quarter more than the previous record annual total achieved just last year.
Apart from the Victoria fillip for the PV market, consumers remain wary of high power prices since few have seen much relief from retailers. “That’s reinforcing the momentum,” Mr Edis said.
The additional solar panels added during the first quarter will deliver their owners a reduction in bills of more than $850 million over the next decade based on current electricity prices, he said.
The ongoing rally in renewable energy is greater in large-scale solar and wind farms, with more than 8100MW under construction. Victoria is also grabbing the lion’s share of the 20,000-plus jobs generated by these projects.
According to Green Energy Markets, Victoria has created 7580 jobs from the wind and solar farms being built. That tally is more than 52 per cent greater than the number of similar jobs in Queensland and almost double those being generated in NSW.
In March, renewable energy sources supplied about 19.7 per cent, or 3839 gigawatt-hours, of the electricity to the country’s main grids, the consultancy said. That supply was enough to power about 9.5 million homes, and saved the equivalent of about 2.7 million tonnes of carbon-dioxide.
The installation of small-scale solar PV totalled more than 23,000 last month, with the average size of residential units reaching 6.6 kilowatts. That section of the market employed some 7857 people in March, with Victoria’s 2134 pipping those in NSW and Queensland, with about 2000 in both.
If the rate of rooftop installations were to continue until 2022, the forecast extra generation of more than 10,000 gigawatt hours would alone top the annual electricity generated by AGL’s Liddell coal-fired power station. The Hunter Valley plant is scheduled to shut down that year.
The growth of the renewables sector could slow sharply in coming years without clearer energy policy, particularly at a national level.
The Renewable Energy Target, which has been the main support for new large-scale generation in recent years, may yet be met ahead of its 2020 goal.
Federal Labor backs the Turnbull government’s National Energy Guarantee as the overarching policy to replace the RET, while the Coalition is promising to help underwrite new generation capacity if re-elected.
Energy Stuff specialises in Residential Solar with emphasis on Repairs, Replacements and upgrades. We also provide new systems, battery storage, Small Commercial, Off-Grid systems and smart monitoring systems. Energy Stuff only uses CEC accredited installers and we fully comply with the Victorian Govt. Solar Rebate Program.
Batteries are critical for our clean energy future. Luckily, their cost has dropped so low, we might be much closer to this future than we previously thought.
In a little less than a year, the cost of lithium-ion batteries has fallen by 35 percent, according to a new Bloomberg New Energy Finance report. Cheaper batteries mean we can store more solar and wind power even when the sun isn’t shining or wind isn’t blowing. This is a major boost to renewables, helping them compete with fossil fuel-generated power, even without subsidies in some places, according to the report. Massive solar-plus-storage projects are already being built in places like Florida and California to replace natural gas, and many more are on the way.
The new battery prices are “staggering improvements,” according to Elena Giannakopoulou, who leads the energy economics group at Bloomberg NEF. Previous estimates anticipated this breakthrough moment for batteries to arrive in late 2020, not early 2019.
According to the report, the cost of wind and solar generation is also down sharply — by between 10 to 24 percent since just last year, depending on the technology. These numbers are based on real projects under construction in 46 countries around the world.
The lower battery prices have big implications for electric cars, too. There’s a key cost threshold of about $100 per kilowatt hour, the point at which electric vehicles would be cheap enough to quickly supplant gasoline. At this rate, we’ll reach that in less than five years.
What’s driving the plunge? Giannakopoulou cites “technology innovation, economies of scale, stiff price competition and manufacturing experience.” Other storage methods, like pumped hydro, still account for the vast majority of energy storage capacity, but lithium-ion batteries are much more flexible and don’t require specific locations or environmental conditions to work. Like everything in the built environment, lithium-ion batteries also require mining and manufacturing. There’s still a chance that some new exotic battery technology will quickly supplant lithium-ion, but its ubiquity and — now — cheapness will be hard to beat.
Electric vehicles will become cheaper to own and operate than gas ones. In places like California, Texas, and Germany, electricity prices have occasionally dropped below zero — a sign that the grid wasn’t yet ready to handle the glut of renewable energy produced there. Now, more of that cheap power will be stored and passed on to consumers. This could be the moment when renewable energy starts to shut down fossil fuel for good.
Energy Stuff helps provide battery solutions to residential and small commercial solar systems. Our battery ready systems range from small to very large depending on client needs. There batteries can be internal and external installations with weatherproof storage available.
Luxury carmaker Porsche has given fans a glimpse of it’s all-electric Taycan as it gears up to debut its premium electric vehicle this September 2019.
With the carmaker reporting that over 20,000 people have pre-ordered its first full electric vehicle, the Taycan will come equipped with an 800-volt system that will charge at rates of 350 kW – making recharging its battery a task that will take as little as 4 minutes to add an extra 100km range.
Stefan Weckbach, head of battery electric vehicles at Porsche, says the emphasis in creating the Taycan has been on ensuring it is not set apart from its ICE counterparts by virtue of its electric powertrain.
“As the first fully electrical Porsche, the Taycan has to show that it is a fully-fledged member of the Porsche brand,” he says. “Of course, this is a great challenge – and a huge expectation, both internally and externally.”
The camouflaged image appears to show a vehicle that differs somewhat from its concept version, the Mission E (although granted, this could be due to its wrap).
As part of a €6 billion ($A9.6 billion) investment in electromobility, the Taycan will Porsche says will also be joined by its second electric mode, an all-electric Macan, and will also be produced as in a crossover GT style.
It will be produced at Porsche’s Zuffenhausen car plant, which it has been readying for production and says will eventually operate as a totally carbon neutral factory and will provide an additional 5,000 jobs.
In addition to its pure electric drivetrains, Porsche says its hybrid models are also doing well – 60% of its Panameras sold in 2018 were “e-Hybrids”.
“In the 2018 financial year, our attractive product range enabled us to once again significantly increase deliveries. Porsche is synonymous with emotional petrol engines and high-performance plug-in hybrids; in the future it will be just known as well for pure electric drive systems,” said chair of Porsche AG’s executive board, Oliver Blume, in a statement to the press.
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‘Electric vehicles can therefore serve as units of temporary energy storage and become key drivers in the development of renewable energy. In this way, the electricity grid optimizes the supply of local renewable energy and reduces infrastructure costs.’
French manufacturer Renault has announced its first large-scale pilot into reversible electric charging, kicking off in the Netherlands and Portugal.
In a statement released this week, the company says: “Our alternating-current technology has the particularity of placing the reversible charger inside vehicles, so it just requires a simple, inexpensive adaptation of the existing charging terminals”.
Renault will introduce a fleet of 15 Zoe electric hatchbacks (pictured) fitted with vehicle-to-grid charging during the course of this year.
The pilot programs will first launch in Utrecht in the Netherlands, and Porto Santo Island in Portugal this week. Further trials are scheduled to roll out in France, Germany, Switzerland, Sweden and Denmark.
For those unfamiliar with the idea of vehicle-to-grid charging, Renault describes it as the following:
Vehicle-to-grid charging—also called reversible charging—modulates the charging and discharging of electric-vehicle batteries in accordance with users’ needs and the grid’s supply of available electricity. Charging reaches its maximum level when the electricity supply exceeds demand, notably during peaks in production of renewable energy. But vehicles are also capable of injecting electricity into the grid during peaks in consumption.Electric vehicles can therefore serve as units of temporary energy storage and become key drivers in the development of renewable energy. In this way, the electricity grid optimizes the supply of local renewable energy and reduces infrastructure costs. At the same time, customers enjoy greener, more economical consumption of electricity and are financially rewarded for serving the electricity grid.
The French manufacturer says its pilot will lay the groundwork for its future vehicle-to-grid offerings, including underlining the technical and economic advantages of the technology, and establishing common standards to facilitate an industrial-scale rollout.
Renault also says the program will help it assess the “value of services produced for the local and national electricity grid” like encouraging the use of solar and wind energy, reducing infrastructure costs, and working on the legal framework of a mobile-energy-storage scheme.
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A New South Wales-based effort to develop renewable hydrogen storage solutions – including a 5kWh home solar storage system – has received $3.5 million in backing from green investment outfit Providence Asset Group.
Tamworth-based company H2Store is working on the technology in partnership with the University of New South Wales, which promises to overcome one of the key barriers to realising the potential of green hydrogen in Australia – storage and transportation.
“The biggest challenge with hydrogen is it is very low density, and it needs big storage tanks, which makes transporting it not viable,” H2Store’s Llewellyn Owens told the Northern Daily Leader last week.
“We’ve made a metal that absorbs the hydrogen and then releases it, which makes it very easy to transport. We’ve known that you can transport hydrogen this way for a while, but the metal had to be heated up to 300 to 400 degrees for the hydrogen to be released. This one basically operates entirely at room temperature.”
The UNSW said on Tuesday that the money from Providence Asset Group would be used to deliver phase one of the four-stage project, including the creation of a home hydrogen storage prototype to compete with – and even outperform – current home battery systems, like the Tesla Powerwall.
The team hopes to have a 5kWh home storage system prototype ready by the end of this year, and a product on the market late in 2020. This would be followed by a “ramped up” 15kWh commercial-scale storage system.
“We will be able to take energy generated through solar panels and store it as hydrogen in a very dense form, so one major advantage of our hydrogen batteries is that they take up less space and are safer than the lithium-ion batteries used in many homes today,” said Professor Kondo-Francois Aguey-Zinsou from the UNSW School of Chemical Engineering.
“We can actually store about seven times more energy than the current systems.
“This means that in a residential scenario, people will be able to store a lot more energy using the same footprint as Tesla batteries, to potentially power their home, charge their cars and still have excess to sell back to the grid.”
Other benefits to the UNSW/H2Store’s technology, the team says, include a lifespan of about 30 years – compared with around 10 years for some batteries – and none of the fire risk associated with lithium-ion systems.
And at the other end of the energy storage scale, the researchers are also working on system for solar and wind farms that will include the design of storage vessels suitable for hydrogen export, and which could in turn have potential to replace diesel in remote generation and large transport applications.
“As the hydrogen technology develops, we will see a new cost-effective alternative to chemical batteries, remote electricity generation, household heating and increased range of hydrogen vehicles,” Owens said.
According to the Northern Daily Leader, the idea has attracted a total of $7 million in investment, with another $3.5 million previously committed by an unnamed company.
The $3.5 million from Providence Asset Group follows last month’s signing of a 10-year dealbetween the asset manager and UNSW Sydney to accelerate research and development of sustainable energy technologies.
UNSW Dean of Engineering Professor Mark Hoffman said Australia had a real opportunity to lead to world in hydrogen storage, energy and transportation solutions.
“This is a very exciting project and I am very grateful to Providence Asset Group for investing in the pioneering work being done at UNSW. I look forward to watching the developments over the next 12 months,” Hoffman said.
Indeed, the investment from Pioneer marks the second financial endorsement of renewable hydrogen technology in as many days, with the federal government on Tuesday granting $3.1 million to a Toyota Australia project to establish a green hydrogen hub powered by solar and battery storage at one of its old car manufacturing plants in Altona North in Victoria.
An ARENA report prepared in 2018 by consultants ACIL Allen found enormous potential in an Australian renewable hydrogen market, including $10 billion in exports over 20 years, and 16,000 new blue-collar jobs, mainly in regional areas.
Energy Stuff specialises in Residential Solar with emphasis on Repairs, Replacements and upgrades. We also provide new systems, battery storage, Off-Grid systems and smart monitoring systems so call us if we can be of support 1300 656 205 or go to our website at http://www.energystuff.com.au
The most affordable version of Tesla’s Model 3 electric sedan is now available in the US, but there will still be a wait for those in other parts of the world, according to CEO and founder Elon Musk.
The Tesla Model 3 has been a game changer for the electric vehicle market, becoming the best-selling car in its class in 2018 and its arrival in Australia in mid-2019 will also mark a major milestone for the local automotive market.
With an asking price starting at $US35,000 (just under $A50,000 at today’s rates, but before GST and other add-ons)) before incentives and fuel cost savings, the addition of the “Standard range” Model 3 last week to Tesla’s US configurator was so gladly received it sent the EV maker’s website into meltdown.
Tesla also added a second upgraded version of the base Model 3 to its website, known as the “Standard Range Plus”, which for an additional $US2,000 gives the driver 20 miles (32km) more range, 10mph (16km/hr) higher top speed and a slightly faster acceleration of 0.3 seconds from 0-60mph (0-96.5km/hr).
However, although the more expensive Long Range and Performance versions of the Model 3 are now being delivered to long waiting customers in Europe and China, there will still be a wait for those wanting to purchase the cheaper versions.
Following the announcement of the Tesla Model 3 on Friday, Musk stated via social media channel Twitter that the base versions would arrive in Europe in around 6 months, with Asia in 6 to 8 months.
The Model 3 is slated to arrive in Australia in mid-2019, but it is expected that the Long Range and Performance will be the versions first made here in Australia, as has been the case overseas.
If the arrival of the base Model 3 follows the same delay as its appearance in China (about 4 months), this means that Aussies may not see the base Model 3 until early 2020.
That is of course dependent on when right hand drive versions of the base model begin production – Musk confirmed in a press conference on Friday that a blend of high and low-priced models would be in production at the same time, which suggests that the RHD base Model 3 production could start sooner than later.
With both the UK and Australia are patiently awaiting the start of RHD production, reports that Tesla has registered at least 2 RHD VINs has many reservation holders hopes up that a mid-2019 arrival in both countries will be achieved.
Of course, registration of VINs does not mean those cars have yet been built, but it is a step in the right direction.
When the base version of the Model 3 does arrive, it’s worth taking note that Musk himself has suggested that the Standard Range Plus version is better value for money.
“For a small amount more you can get basically a whole lot more like roughly 6% price increase gets you … almost 10% range increase and a 6% power increase and … mostly towards the premium interior,” he said at Friday’s press conference.
Worldwide, demand for the Model 3 is expected to be up to 500,000 units per year (annualised). Although Tesla has not released numbers of how many reservation holders there are in Australia, Musk said on Friday that those holding reservations would have first choice to purchase the base Standard Range Model 3 once it arrives.
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Solars panels, while a game-changing feat of engineering, have historically been—depending on your aesthetic preferences—a bit of an eyesore. But this is changing since researchers from Michigan State University have developed see-through solar panels. Completely transparent. Think windows. These ingenious panels will be able to provide numerous functions in future architectural design, not to mention other fields such as mobile phone technology, and cars.
The see-through cells can be used on buildings, mobile phones, and even cars
The American inventor Charles Fritts created the first commercial solar panel way back in 1881, describing it himself as “continuous, constant and of considerable force.” But the panels were somewhat inefficient: the design was perfected for commercial use in 1939 by American engineer Russell Ohl, who created the solar cell design that we have become familiar with today.
The Michigan State University research team, already having an engineering formula that worked, focused on transparency instead. What they came up with has been termed a “transparent luminescent solar concentrator,” or TLSC, which can function as a coating over clear surfaces like windows, harvesting solar energy without affecting the function of the window to let in light.
Dr. Richard Lunt leads the Michigan State University research team
The technology employs organic molecules, which function on a light wavelength not visible to the human eye. Dr. Richard Lunt is the assistant professor of chemical engineering and materials science at MSU’s College of Engineering, and he explained in more detail: “We can tune these materials to pick up just the ultraviolet and the near infrared wavelengths that then ‘glow’ at another wavelength in the infrared. The captured light is transported to the contour of the panel,” he continued, “where it is converted to electricity with the help of thin strips of photovoltaic solar cells.”
TLSC could make a huge impact on energy efficiency
The design is ideal for use in architecture. As more solar energy can be harvested from the larger surface area of a building’s facade, as opposed to its rooftop, TLSC could make a huge energy impact on tall buildings. Especially glass ones. TLSC does not affect the overall look of the building or compromise the focus of the architectural design, but lends the benefits of a hyper-efficient energy technology to existing properties. TLSC can also be integrated into old buildings.
The New York Timesreported favorably on the new technology: “If the cells can be made long-lasting, they could be integrated into windows relatively cheaply, as much of the cost of conventional photovoltaics is not from the solar cell itself, but the materials it is mounted on, like aluminum and glass,” they wrote. “Coating existing structures with solar cells would eliminate some of this material cost.”
The university team’s ongoing research is funded by the Center for Excitonics
Boasting a triple whammy of appealing characteristics— being transparent, impactful, and cost effective—the TLSC transparent cells could change the face of solar power completely. And if they prove commercially viable, Dr. Lunt continued, the power they generate could “significantly offset the energy use of large buildings.” The university research team has received funding from the Center for Excitonics, an Energy Frontier Research Center financed by the Department of Energy, to continue their innovative research into the energy-producing efficiency of the transparent cells. Dr. Lunt believes that some basic modifications, such as stacking the cells, could increase TLSC efficiency from 1 percent to around 10 percent.
Dr. Lunt’s excitement reflects that of the team at large. “We’re not saying we could power the whole building,” he clarified, “but we are talking about a significant amount of energy, enough for things like lighting and powering everyday electronics.”
The future is looking clearer and clearer.
Energy Stuff specialises in Residential Solar with emphasis on Repairs, Replacements and upgrades. We also provide new systems, battery storage, Off-Grid systems and smart monitoring systems so call us if we can be of support 1300 656 205 or go to our website at http://www.energystuff.com.au
A ground-breaking rooftop solar trading platform that cuts out the energy market middle man and allows consumers to buy and sell renewable power at prices negotiated among themselves has been launched across four Australian states.
The platform – which, among other things, provides access to solar for consumers otherwise unable to invest in the technology – was opened for registration on Thursday by upstart retailer Energy Locals, in partnership with solar trading software developer, Enosi.
Under the new partnership, customers can negotiate the sale of excess rooftop solar generation at rates individually agreed upon with their chosen buyers, in a way the two companies hope will take pressure off the grid and – for consumers – eradicate hidden fees.
As Enosi CEO Steve Hoy explains it, customers of Energy Locals will be able to trade with each other, set their own price – a maximum buy price, or a minimum sell price – and nominate a person or business they wish to sell to.
The buyer pays the grid tariff – which of course varies on different parts of the NEM – while the seller gets the price negotiated, which could range from zero, in the case of charitable or family solar donations, or might be slightly higher than the applicable solar export tariff.
For households with no one party nominated to buy their excess solar, they can trade into a pool of buyers, which is set up like a stock market, with maximum and minimum prices set every half hour, and trades are reconciled at the end of the month.
All Energy Locals customers, meanwhile, pay a flat, GST inclusive membership fee of $4.50 a week, and default grid electricity usage is charged at Energy Locals’ wholesale prices.
But as Hoy points out, the solar trading platform is about more than helping customers save a few dollars on energy bills.
Indeed, the two companies share one overriding goal in this venture, which is “lifting the veil on a deeply distrusted industry and giving customers transparency and control over pricing.”
“We’re removing the need for someone to be reliant on a traditional retailer with integrated centralised generation, that is produced a very long way away,” Hoy told One Step in an interview on Thursday.
“At the moment, customers are just purely price takers. They’re really completely exposed to whatever games (gen-tailers) choose to play in the wholesale market.
“There’s not a lot you can do about it if you can’t invest in solar or your property isn’t suitable.”
According to Energy Locals CEO Adrian Merrick, this has been particularly evident in the Victorian market, of late, into which the company is set to launch, but has been holding off, on account of it “looking nuts.”
“What we’re seeing in the market is the integrated generators and retailers have actually been choosing to run their generation less,” Merrick said.
“At the end of January, we saw people taking some very odd decisions about when to run and not run their plant, and all sorts of strange forced outages.
“We believe there are a lot of offshore derivatives backing their position, which means they were covered from a financial point of view.
“So if you’ve got four units and you take one of them off-line in a major heatwave, you’re going to make a lot more money running three units at high prices than if you had all four running,” he said.
“I think it would be very interesting to look at the next set of financial results… (it would likely reveal) yet more evidence of just the extreme amount of money that people are making from what is a completely broken wholesale market.
“It’s actually a relatively small number of people that are screwing the market in this way. Less than 100 people. Some smart rule changes would deal with this.”
For now – and Energy Locals will be opening for business in Victoria in the next few weeks – the two companies are working with the market they’ve got, and doing what they can to offer customers what they believe is a better and fairer system.
But Hoy and Merrick both note that a few tweaks to market regulations and structure would be very welcome.
“We have designed this so it fits into the market the way it is, but it would benefit form more cost reflective tariffing in many ways.
“We’re trying to support people who don’t have solar, so we would like to see grid tariffs being shared between sellers and buyers.
But they’re not holding their breath in the wait for progress.
“This kind of product directly challenges vested interests in the industry,” Merrick said.
“Customers are going to be much better off when the status quo in this industry is broken.
“What we’ve got here is a platform and proposition for customers that will be able to demonstrate how a rule change would find its way through to lower bills for customers.”
That said, adds Hoy, “the main reason (we’re doing this) is to give people a little bit of control on where they’re getting their energy from.
“It’s a way of proving the providence of (the electricity), and we can prove that the generator didn’t sell it twice – that he doesn’t get a feed-in tariff from (Energy Locals too).”
A neat example Hoy puts forward is based the local primary school.
“Schools struggle to justify solar on the roof, because the school day ends at 3.30pm, and then there are weekends and school holidays.
“But if they can sell that excess solar to the parents, then you’ve got this natural marketplace and the parents are likewise supporting the school.
“In the same way, at the middle of the day, when the school’s energy needs are highest, they can buy from the parents, who are mostly out at work.”
So who can opt in? At the moment, any customers of Energy Locals in south-east Queensland, New South Wales and the ACT can register their interest to take part. Victorian customers can also register to join the platform, but will have to wait around three more weeks until Energy Locals launches in that state.
Energy
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Solar panels now grace the roofs of more than 2 million Australian homes. But when it comes to solar cell efficiency records, the numbers aren’t so clear-cut.
These days, the best silicon solar cells operate at 26.7 per cent efficiency.
Hang on. Only 26.7 per cent? That seems pretty low, especially when you find out that’s under ideal lab conditions.
But don’t diss the efforts of chemists and physicists — 26.7 per cent, and the tiny efficiency gains that led to it, is a big deal.
Put simply, there’s a limit to how much of the sun’s energy can be converted to electricity by solar systems.
In the case of your standard rooftop silicon panels, efficiency tops out at around 32 per cent.
(And that’s a theoretical figure. Out in the real world, silicon panels are around 20 per cent efficient.)
So why does this 32 per cent limit exist, and can we work around it?
How do solar cells work?
First, we need to understand the nuts and bolts of how solar cells, which make up panels, generate electricity from sunlight.
Let’s go with silicon solar cells, given they’re the most familiar.
These cells are made of a silicon wafer that’s “doped” with small amounts of other elements, so electrons flow around a circuit in a particular direction to give us electricity.
Electrons in silicon atoms usually hang out in what’s called a “valance band”. While there, electrons aren’t free to move around, so the silicon acts like an insulator.
But if an electron gains enough energy, it can jump into a higher energy “conduction band” where it’s mobile and — voila! — able to produce electrical current.
The amount of energy needed to bounce between the valance and conduction bands is called the “band gap”.
In solar cells, sunlight in the form of photons provides the energy kick electrons need to traverse the band gap.
And for silicon, that band gap is 1.1 electron volts.
Where does silicon’s efficiency limit come from?
Named after the physicists who calculated it in 1961, a material’s maximum efficiency is called the Shockley-Queisser limit.
It’s a fairly complex calculation that takes into account a bunch of factors. A big one is that not all photons are created equal when it comes to energy.
The sun spits out a wide spectrum of photons, from ultraviolet through to infrared.
But redder photons carry less energy than their bluer counterparts, said Andrew Tilley, a chemist at the University of Melbourne’s Bio21 Institute.
“So light with energy below the band gap passes through the silicon, unabsorbed.”
That ends up being a large proportion, too — around 20 per cent of sunlight falling on a solar cell simply does not contain enough energy to provide that 1.1-electron-volt boost.
What happens to two-thirds of the sun’s energy?
Photons that aren’t energetic enough provide a large chunk of wasted energy. This is called the transmission loss.
And then there are heaps of photons that are tooenergetic.
Take, for instance, an orange photon with 2 electron volts hitting a silicon solar cell. It kicks up an electron from the valance band to the conduction band, but traversing the band gap only requires 1.1 electron volts.
This leaves 0.9 electron volts of energy left over, which manifests itself as waste heat or, in fancy physics terms, thermalisation loss.
“It’s a massive challenge,” Dr Tilley said.
In the case of silicon solar cells, thermalisation and transmission account for about 35 and 20 per cent, respectively, of efficiency loss.
The remaining 15 per cent or so is energy lost due to other quirks of optics and thermodynamics.
Are we stuck with max efficiency of 34 per cent?
Of course not. Physicists and chemists are finding ways to capture energy that would usually be lost in transmission and thermalisation and turn it into electricity.
Let’s see how we can get around the big thermalisation problem. One way is to stack layers of solar cells, with each absorbing a different part of the spectrum.
The key is to use old tried-and-tested silicon with another semiconducting material to create a “stacked” solar cell.
Stacked solar cells have been used for years, but generally only in solar-powered devices where space is a premium, like satellites and spacecraft.
Triple-layer solar panels that were popped on the now-dead Spirit and Opportunity Mars rovers back in 2003, for instance, boasted a 27 per cent conversion efficiency.
But they were made of gallium-arsenide which, even now, costs up to $300 per watt — about 100 times more expensive than silicon panels.
A new and quite promising candidate is a group of materials called perovskites, which have “shot from obscurity to being awesome in a short period”, said Niraj Lal, a visiting fellow at the Australian National University.
The beauty of perovskites — aside from the fact they are cheap and made from plentiful materials such as lead — is that their band gap can be “tuned” depending on their chemical make-up.
Last year, Oxford researchers stacked a perovskite capable of catching high-energy, blue photons on top of a silicon cell, which then caught lower-energy photons towards the red end of the spectrum, to create a stacked or “tandem” solar cell that was 28 per cent efficient.
“When you start combining these cells, then you can really go past the Shockley-Queisser limit,” Dr Lal said.
“Just in the past year, they’ve cracked records to be better than silicon alone.”
Then there are tricky and complicated methods that take high-energy photons and manipulate them so solar panels can use them without producing as much waste heat.
There are also efforts to catch and manipulate two low-energy photons to create one high-energy photon. This is called photon upconversion.
Other materials, like zinc telluride, can be designed to have a mid-band-gap stepping stone of sorts. These are called intermediate band materials, Dr Tilley said.
“The idea is electrons can use a low-energy photon to get halfway between the valance to conductance bands, then another to get them to conductance.”
While Dr Lal thinks tandem perovskite-silicon solar cells will likely be the next phase of commercial solar cells, there are still quite a few kinks to iron out.
Perovskites are often made of toxic materials like lead and they degrade faster than silicon, especially if they get water on them.
Silicon solar cells tend to come with a guarantee that after 25 years of use, they’ll still operate at 80 per cent of their initial efficiency.
“The challenge is how to make perovskites stable, so they last in a harsh climate like Australia’s,” Dr Lal said.
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