In ‘Batteries’ Category

ReNew 141: Store your solar

ReNew 141 editorial: measure it up – the benefits of monitoring

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I’M A big fan of energy monitoring. Most days we check the app from our electricity retailer to keep an eye on usage from the day before. Broken down into half hourly blocks, this proved particularly useful to see the (good) results as we switched out halogen lights for LEDs and got better at turning things like the computer and printer off when not in use (hibernation mode on PCs means you can easily pick up where you left off, and an ecoSwitch is great for quickly turning off printers or TVs). The app also keeps historical usage so you can compare winter to summer, or this winter to the last, useful for spotting a problem energy-user (a plug-in heater perhaps), before the costs start to add up.

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Taking it a step further, you can even get near-real-time monitoring. Having just installed a solar system, I’m now a convert to its app which shows almost instantaneous solar energy production and electricity usage. Such real-time data makes it even easier to work out what’s chewing up energy—or as happened today, to tell whether your child has turned on the washing machine as promised while you’re out! Plus, the generation data helps you schedule appliances to run at a good time for solar self-consumption or to work out if your solar system is performing as expected.

In this age of Internet of Things and wi-fi connectedness, there are now so many more options for energy monitoring: some connected to a smart meter, some to a solar or battery system and others independent of these. Our guide helps you understand which type might work for your situation—definitely worth a look to help you reduce your bills and environmental impact. It’s just a pity the same tools aren’t available for gas monitoring.

Our other big topic this issue is energy storage—perhaps more of a barbecue-stopper than energy monitoring! It’s been heartening to see grid-scale battery developments in South Australia and Victoria, as a way to provide grid stability and assist with peak demand. There are solutions other than keeping ageing coal-fired power stations like Liddell open.

It’s great to see early adopters of home battery systems in our audience. Their ‘use cases’ will provide insights and help the market develop—similar to the role many ReNew readers played in the early solar days. It’s also good to see industry trials underway to measure the community benefits, plus government subsidies which a few of our case studies have been able to access. We’ve reviewed the market to provide pros, cons and the range of battery systems available. It’s a rapidly developing area, so we’ll keep providing updates and case studies to help guide your approach.

Plus: ‘home truths’ on how comfort and efficiency can go hand-in-hand, a heat pump hydronic system in action, using ratings tools during rather than after the building design process (there’s even a free tool available so you can DIY), second-life for EV batteries, DIY garden irrigation, a community aiming for net zero energy and much more. Enjoy!

Robyn Deed
ReNew Editor

ATA CEO’s Report

AS ReNew goes to print we are in the final stages of preparing for Sustainable House Day 2017. We are very excited to have 200 homes opening up across Australia, with 20,000 people expected to visit one or more of these homes on the day. The event provides a unique opportunity for people to come and learn how to make their homes more environmentally friendly, more comfortable and cheaper to run.

A diverse range of homes are opening their doors, including granny flats, student rental accommodation with battery storage, new contemporary 10 Star homes and homes where the owners have made gradual changes over a number of years. What they all have in common is that they’ve worked hard to improve the energy efficiency of their homes.

The average Australian home has an energy efficiency rating of just 1 to 2 Stars, making them cold in winter and warm in summer. Draughty and leaky, these homes use about 40% of their energy on heating and cooling. By walking into a well-insulated home you can instantly feel the difference in comfort.

We are also seeing new trends with an increasing number of homes that are all-electric and more homes incorporating battery storage or at least planning for future installation. They must have been keeping up-to-date by reading ReNew!

Sustainable House Day would not be possible without the generosity of the households opening their doors and over 200 volunteers who help out on the day. They are all part of ATA’s community of change, not only taking practical action for a sustainable future themselves but sharing their experiences and inspiring people in their community to do the same.
Donna Luckman
CEO, ATA

You can purchase ReNew 141 from the ATA webshop.

batteries

Energy storage buyers guide

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With rapidly increasing demand, we survey the battery storage system market. We present the latest systems and the considerations to guide your approach.

WITH the steadily rising cost of grid electricity, many people are considering how to make the best use of the solar electricity they generate, to offset as much mains grid power as they can.

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While there are a number of ways to do this, including shifting loads to the middle of the day or diverting excess energy to heavy loads such as an electric water heater, if those options are not possible or desirable, or you have other needs, such as a degree of backup during grid failures, then an energy storage system is an option.

There has been a move in recent years towards storage systems that contain the batteries and other components in a pre-configured ‘storage in a box’ module for connection to a PV array.

These sorts of pre-configured energy storage systems are the focus of this buyers guide. We do not cover individual batteries/cells in this guide, as they have their own buyers guide, the most recent in ReNew 131.

Pros and cons of ‘storage in a box’
There are several advantages to this sort of ‘storage in a box’ system.

Firstly, installation is usually quick as much of the wiring between components has been done.

Secondly, it often makes for a neater system as many components and their associated wiring are enclosed in a single cabinet.

There are some disadvantages too, including less flexible system sizing—most suppliers have a few standard battery bank sizes that they offer.

However, storage units may be modular so that multiple units can be used to make up the required capacity, and some are designed to have extra battery modules slotted into the case to increase capacity.

Read the full article online or in ReNew 141, covering:

  • Economics on the grid
  • The environmental equation
  • Community benefits of batteries
  • Types of system: AC batteries, Battery-only products & DC coupling, All-in-one units
  • Backup power
  • Which battery chemistry?
  • Battery smarts
  • Safety, Quality and Warranties
  • Sizing your system
  • Energy management
  • Retrofits
  • Maintenance and upgrades
  • Table of systems

For the abbreviated table of storage systems in PDF format, click here.
For the full updated Solar Quotes table of storage systems, click here.

1940s cottage with battery

Battery system case studies

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1940s cottage with battery

IN 2016 Liz and Charlie extended and renovated their 1940s cottage in Ainslie, a suburb of Canberra, applying passive solar design to the extension and retrofitting insulation and sealing to the existing home.

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In early 2017, they also added 4.48 kW of solar, an LG Chem 10 kWh battery and Reposit software, costing around $20,000 as a package, after an ACT government subsidy.

“We chose to get a battery as we wanted to maximise self-sufficiency,” says Liz. They like that the battery allows them to use their generated electricity at night. They chose the LG Chem battery as it didn’t need to be undercover.

Their average usage is around 8 kWh to 9 kWh per day and currently, according to Reposit, they’re achieving 96% to 98% self-consumption, depending on the weather (and therefore their solar generation) and their electrical load for the day.

“Yesterday it was partly cloudy, and we generated 26.8 kWh, used 9.9 kWh ourselves, exported 17.2 kWh and imported just 0.3 kWh,” says Liz. “That’s pretty typical.”

The battery is generally fully charged by 11 am; on a sunny day it can be charged by 9.30 am, and occasionally not until the afternoon if it’s very grey.

The real-time monitoring available via Reposit is fascinating, says Liz. “It gives us useful feedback on our electricity usage patterns and, as a result, we make better choices about electricity consumption.”

For example, they noticed their hot water heat pump was coming on during the night when they’d prefer it to operate during the day from solar, so a timer to prevent that happening is on their to-do list.

Retiring sustainably

WHEN Julie May retired and bought a new home in Canberra, she decided to invest her savings in a sustainable lifestyle to reduce both her environmental footprint and her cost of living in retirement.

The house already had some good energy-efficient features including R3.5 ceiling insulation, R2 wall insulation, north-facing living areas with eaves to exclude sun in summer, high/low windows for cross-ventilation and a Daikin split system for heating and cooling.

Her changes began in July 2015 with the purchase of an Audi A3 e-tron plug-in hybrid electric vehicle, followed by installation of a 4.5 kW solar system (Nov 2015) and a 6.4  kWh Tesla Powerwall with Reposit for energy management (Aug 2016).

Julie also disconnected from gas in 2016, switching from instantaneous gas to electric-boosted solar hot water. Her gas bills previously comprised 80% fixed charge and only 20% for the gas itself, so going all-electric has meant a big saving.

She can now run her home and car mostly off solar and the stored energy in the battery, thus keeping imports low (1 to 2.5kWh/day, down from 10 to 23 kWh/day, counting electricity and gas).

Other notable achievements:

  • Julie has travelled 18,000 km in her Audi over the last two years and averaged just $155/year for petrol.
  • Reposit monitoring has meant she’s been able to better stagger appliance use so that grid energy is seldom required.
  • Julie has been paid Reposit premium GridCredits on several occasions for providing energy from the battery when there was high peak demand, e.g. she was paid $5.24 for four ‘grid credit events’ on 10 Feb 2017.
  • She also runs a cordless battery-powered mower as part of her all-electric home!

Eco additions

GREG and Maria built their passive solar house in Sydney in 1988, with a view to living as sustainably as possible. As technology has improved and become more affordable they have added more sustainable features.

A solar hot water system was the first addition in 1990, followed by 6000 L of rainwater storage in 2009, 2.8 kW of solar PV in 2010 and double glazing in May 2017.

Then, just six weeks ago, in late July 2017, they added a Tesla Powerwall 2 with 14 kWh of battery storage ($9300 installed).

Their motivations included to increase use of their solar and to ensure supply during blackouts, particularly to run tank pumps as they are in a bushfire zone.

The house’s energy consumption averages around 10 kWh per day, and the solar and battery were sized for this.

They expect they’ll use a little from the grid during the winter quarter, but they should be pretty well energy independent the rest of the year.

So far, the system has performed better than expected, with just a few days requiring grid draws of up to 2.5 kWh—usually when they’ve used their fan heater in the evening.

The battery charging and discharging is not timed—“it just works,” says Greg. “My experience is that there’s no need to manage it. So far, our limited experience is that if there’s a sunny day, the battery gets to 100% during the day with a small amount of grid export after that, and then the house runs off the battery all night.”

They can now run multiple appliances without drawing energy from the grid. Greg notes: “Being AC-coupled, the battery and solar add together, so we can supply a load of 7 kW quite easily, which was not possible before the battery.”

 

Read the energy storage guide and more case studies in ReNew 141.

IMG_1790

Towards grid independence

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What happens when a home with very low electricity use adds a battery? Terry Teoh describes his home’s interesting results.

OUR house is an Edwardian three-bedroom brick home renovated in 2010 along sustainable design lines. With two occupants, our house achieves a very low average electricity consumption of 2.4 kWh/day, though note that gas is (currently) used for space heating, cooking and boosting of solar hot water.

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We installed a 5 kW solar PV system in December 2016. With the array oriented east and west, the seasonal difference in energy production is accentuated compared to a north-facing array: our system produces on average 26 kWh/day in summer and 7 kWh/day in winter.

In April 2017, we added a 4 kWh Sonnen eco8 battery to our system to provide solar load shifting—storing solar energy produced during the day for use at night.

In the first two months of operation (to June 2017), our house has moved from 30% to 70% grid independence—i.e. 70% of our energy is now generated by our solar system.

Interestingly, that 70% is lower than we expected given a substantially oversized solar array and battery. It turns out that our standby energy usage is too low to be served by our inverter!

However, it’s still a good result and the battery has lifted solar self-consumption from 5% to 50% and paved the way for us to disconnect from the gas network and move to an all-electric, renewably powered household.

Motivations
Our motivations for installing a battery system included a desire to maximise solar self-consumption and grid independence. The latter is not out of antipathy for energy companies or the grid. We want to stay connected to the grid.

The grid is good; it will just be used in a different way in the future to support a decentralised energy system where consumers will have more control over how they make, use, store and share energy.

Read the full article in ReNew 141.

Relectrify

Second life for EV batteries

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We’ve looked at recycling end-of-life batteries before, but what if they could be reused instead? A startup in Melbourne is making that happen for electric vehicle batteries.

In Australia, with just 4000 or so electric vehicles on the road, you’d be forgiven for thinking we can defer dealing with ‘end of life’ EV batteries for a good while yet. However, the global view is quite different.

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Some two million EVs are on the road world-wide (up from around 400,000 in 2013) and, with warranted battery life ranging from five to eight years, a large number of batteries are approaching end of life. Whether that’s a problem or an opportunity depends on your perspective.

Getting value from a second-life battery
Relectrify, a Melbourne-based technology startup, is a company that sees the upside.

At the end of its usable life in an EV, says Relectrify’s Valentin Muenzel, a battery generally has around 2000 charge–discharge cycles left—or about half its life. It may not be suitable for continued use in a car, but there are other uses, in household systems, for example, where the lighter loads can mean it’s still got a useful future.

It’s not quite as simple as plugging a used EV battery in to your home energy system, of course.

One issue is that cells may have degraded differently across the battery pack. A standard battery management system (BMS) will prevent the entire battery from discharging below the fully discharged point of the weakest cell (a passive BMS) or take from those cells with more energy capacity to make up for those with less (an active BMS). The latter can improve the energy output, but the degree of improvement depends on the difference in capacity between the cells.

To maximise the energy output from the battery, the team of engineers at Relectrify has instead designed what they term a “BMS on steroids”.

This outputs full capacity for all cells that are functioning, rather than balancing the current between cells, in effect draining each cell completely to its safe end point voltage each cycle.
It’s a neat ‘plug and play’ system—a circuit board screwed atop the battery screw terminals (or welded if needed) that optimises at the cell level to use all the energy in the cell. It can work with lithium ion batteries as well as other types, including nickel-metal hydride—any that have a ‘contained’ battery chemistry, so not flow batteries, for example.

Firmware updates to the algorithm can be delivered via the cloud, so as they improve the technology, existing systems can benefit.

Read the full article in ReNew 141.

Desert Rose render

A net zero energy home

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A net zero energy home for desert conditions is the mission of the next international Solar Decathlon, but the University of Wollongong’s entry could have applicability far beyond the competition.

The University of Wollongong’s entry in the next international Solar Decathlon is perhaps aptly named. It’s called the Desert Rose, after a plant that can cope with the tough conditions the team will encounter when they build and operate their sustainable house design in the host city, Dubai, in November next year.

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With temperatures of 35+°C every day, less than 2 mm of rain for the month and desert sands that present problems for both greenery and solar panels alike, there are certainly challenges ahead.

Student-led sustainable innovation
What is the Solar Decathlon? Sometimes called the Energy Olympics, the decathlon was started in 2000 by the US Department of Energy to encourage innovation in sustainable, renewably-powered residential buildings.

The contest challenges university student teams to not only design, but also build and operate a home that produces more energy than it consumes—a net zero energy home.

The University of Wollongong (and Australia) first competed in 2013. Amazingly, that entry, the Illawarra Flame (www.illawarraflame.com.au/house.php), won with the “highest score ever recorded,” says a suitably proud Brendan Banfield, building services manager for the 2018 team.

It’s a crash course in construction for the student competitors. The houses they design get built, dismantled and rebuilt, perhaps many times over the course of the competition.

In 2013, the Illawarra Flame was built and dismantled twice before its journey in seven 40-foot containers to that year’s Chinese host city. It took 12 weeks to build the first time (in a warehouse in Wollongong), but then just five days to dismantle and ten to re-assemble on site in China.

It’s an undertaking that gives the student competitors—from diverse fields including engineering, architecture, health, arts, business and communications—incredible hands-on experience in design, construction and problem-solving.

In fact, a US Department of Energy survey (covering four solar decathlons from 2002 to 2009; see www.bit.ly/2jgguaf) found some 76% of past competitors went on to jobs in the sustainable building and clean energy sector, compared to just 16% of non-competing fellow students (and 92% found the competition critical to their job-seeking).

Brendan says, “The technology used or invented is typically five years ahead of the market and 10 years ahead of the building code, giving competitors an ‘edge’ when seeking work or starting a business”—some 16% of those surveyed had started their own sustainability business as a result.

Read the full article in ReNew 141.

Read more about the Desert Rose team and their entry here.

Saltwater_Batteries

Saltwater batteries in use

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When the old battery bank gave out, it was back to diesel for a time at this significant conservation site in the Mallee. But an innovative off-grid upgrade has changed that and led to a significant improvement over the old system, as Trust for Nature’s Chris Lindorff and Tiffany Inglis explain.

UP IN the Mallee, along the River Murray in far north-west Victoria, lies Neds Corner Station, a former sheep property now being restored as a significant natural habitat by the not-for-profit Trust for Nature.

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With an extreme climate—temperatures soar close to 50 °C in summer and frosts occur in winter—and no grid connection, this 30,000 hectare (300 km2) property presents challenges not only for habitat restoration, but also for the off-grid energy system needed to support the on-site rangers and visitors.

Purchased by conservation organisation Trust for Nature in 2002, the site is now home to two rangers and up to 30 visitors at a time: researchers and students studying the flora and fauna; bird groups conducting site surveys; works crews working on neighbouring public land; volunteers assisting with site restoration tasks such as reducing rabbit numbers, replanting local species and installing fences to keep out foxes; and the occasional corporate days and camping trips.

The site includes a homestead, shearer’s huts (used as accommodation), kitchens and conference/workshop rooms, with associated energy needs for heating/cooling, lighting, water pumping, refrigeration and gas cooking.

Energy system, take 1
When the property was first bought by Trust for Nature, the site ran solely on a diesel generator. Then, in 2012, philanthropic donations enabled the installation of a solar power system with a lead-acid battery bank. The system was designed to cater for an average of 25 kWh/day energy use, with a 25 kVA diesel generator as backup.

Over the following years, however, more people came to Neds Corner and energy demand increased, which led to the generator running more often than not.

Frequent, heavy cycling of the flooded lead-acid battery bank meant it performed poorly and reduced its lifespan. Following the failure of multiple battery cells in 2016, the battery bank was disconnected and the diesel generator again became the sole source of electricity.

Read the full article in ReNew 141.

MaxBoegl_windwater

News: Innovative water battery

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Pumped hydroelectric storage to help maintain grid stability is not a new approach for the energy industry—indeed, it was first used in the USA in 1930. However, German wind turbine manufacturer Max Bögl Wind AG has introduced an innovative twist, which they showcased at the Energy Storage North America (ESNA) fair in San Diego in August. The ‘water battery’ combines renewable power generation with a modern pumped-storage power plant to be used in periods of high demand. The pumped-storage power plant is available in three performance classes (16, 24 or 32 MW) and can switch between production and storage within 30 seconds.

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The first project to use the technology is being developed in Stuttgart, Germany. It comprises a windfarm of four turbines, each of which have tower bases with in-built water storage capacity of 70 MWh. These are connected to a hydroelectric power station with 16 MW installed capacity and a lower reservoir in the valley 200 m below.
www.bit.ly/MBWAGWB

Feature image: This windfarm in Stuttgart, Germany, is using wind turbines combined with pumped hydro for energy storage, with water stored at the base of the turbines! Image: courtesy Solar Consulting

3-phase

One phase or three

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If your home has a three-phase power connection, there are a few extra decisions to make when buying appliances, connecting solar or adding batteries. Lance Turner explains.

ALL AC grid electricity is generated using a three-phase system. Because of their relatively modest power needs, most homes are only connected to one of those three phases. However, some homes, such as those that have larger loads, and most commercial premises, have a three-phase electricity connection.

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Larger loads can mean that a single-phase connection would be heavily loaded at times. A three-phase connection may be used as it spreads the power draw across all three phases instead of just one. Interestingly, some homes are connected to just two of the three phases.

If moving your home from gas to all-electric, you may also consider upgrading an existing single-phase connection to a three-phase connection. For an energy-efficient home this shouldn’t really be necessary, but for larger homes or homes with a single large load such as an EV fast charger, an upgrade to a three-phase connection may be desirable or even necessary.

At the very least, smaller (40 amp) single-phase connections may need to be upgraded to something larger, such as an 80 amp connection. Any grid connection upgrade will usually require cables between the residence and the grid to be replaced, which can be expensive, depending on your energy company, location, cable installation type (overhead or underground) and length of cable back to the grid, and may run to several thousand dollars. Shifting from single phase to three-phase will definitely need cable replacement—each phase needs its own cable, and will also require a meter upgrade.

Having a three-phase connection to a home does allow for greater flexibility with appliance selection as you can use either single-phase or three-phase appliances as desired. If you are upgrading to a three-phase connection purely to install a large solar system, then the cost of the connection upgrade must be added to the system cost when factoring in system payback times.

Read the full article in ReNew 140.

Pomona

Battery storage gets competitive

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It seems the convergence of environmental realities and the economics of renewables is finally escalating apace. While large-scale wind and solar farms have been the big focus of the last few years (and continue to be), large-scale battery storage has become ‘the next big thing’.

Globally and domestically, governments and corporations are rolling out big storage projects that will provide the missing link between renewable energy generation and grid stabilisation/meeting peak demand.

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In a few months, Germany will accept delivery of Europe’s biggest battery—a 48 MW/50 MWh lithium-ion unit—that will help provide grid stability in the Jardelund region near the border with Denmark, which currently relies on intermittent wind power. In the USA, its largest battery storage facility, the 20 MW/80 MWh Pomona Energy Storage Facility in Southern California, opened in January this year. India’s first (10 MW) grid-scale battery storage system was also launched in January, and Bloomberg New Energy Finance is slating that 800 MW of storage could be commissioned by 2020.

In Australia, in the wake of South Australia’s recent ‘crisis’ of energy supply, a key response from the SA Government has been to support the construction (by winning tender, before year’s end) of a 100 MW battery —Australia’s largest to date—with $150 m from a renewable technology fund. There have been 90 expressions of interest from 10 countries. [Update: this tender has now been awarded.]

One of the companies competing, Australia’s Lyon Group, has said that, regardless of the outcome of the tender process, it will build a $1 b battery and solar farm—believed to be the world’s biggest—by the end of this year, in SA’s Riverland region: 3.4 million solar panels and 1.1 million batteries will generate 330 MW of electricity and provide 100 MW/400 MWh of battery storage (depending on configuration). The project is fully financed, with grid connection already well progressed. The company’s 120 MW solar/100 MW/200 MWh battery Kingfisher project in SA’s Roxby Downs is also due to start construction in September 2017, to be running by June 2018. A third smaller storage project of 20MW/80MWh is also being developed on Cape York.

The Victorian Government recently announced a $20 m tender, as part of its $25 m Storage Initiative, which calls for proposals detailing the construction of large-scale storage facilities in the state’s west. Applications close mid-June and, from the process, the government aims to deploy up to two projects that will provide at least 100 MWh of battery storage by January 2018.

The ACT’s Next Generation Storage Program is committed to providing around 36 MW of distributed battery storage, through subsidised residential batteries, which plans to see 5000 homes signed up by 2020. And in the Northern Territory, results of a tender for 5 MW of battery storage (the nation’s largest, until the SA and Vic announcements, above) are about to be released.

Feature image: A peek into the Pomona Energy Storage Facility; at 20 MW/80 MWh, currently the largest in the USA. Image: Pomona Energy Storage, courtesy AltaGas Ltd

Battery installation at Stucco

Battery bounty: saving students money

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This innovative project is demonstrating how a solar + battery project can work for both the student tenants and the managing co-op in a low-income apartment complex in Sydney. Robyn Deed talks to the project managers.

GETTING buy-in from all the apartment owners on a solar project in a new apartment building can be hard, but make that a solar + battery project for an existing heritage building used for low-income student housing, and an extra level of energy and commitment is required. But the residents and researchers behind the Stucco Co-operative Housing project in Sydney’s inner-west have achieved just that with a 30 kW solar + 42 kWh Enphase battery installation designed to reduce the 40 student residents’ energy bills and provide a roadmap for other such projects.

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Why is solar so tricky for apartments? “The main issue is the ‘split incentive’,” says Bjorn Sturmberg, a former resident of Stucco and one of the project managers. If the apartment owner isn’t the tenant, there’s little incentive for them to pay to install solar when the savings will go to the tenant.

How to get solar onto more apartment buildings is an issue the City of Sydney is currently grappling with, so Stucco “hit the bullseye” says Bjorn, when they put in an application for funding to find an approach that would work for the complex of eight units—with the opportunity to research a significant battery storage installation also in their favour. The result was a grant of $80,000 matched with $50,000 from the Stucco co-op. For City of Sydney, the ‘return’ on their grant is a report on just what the barriers are and guidance on how to overcome them.

Read the full article in ReNew 139.

Nissan Leaf battery

Keeping your EV battery healthy

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In the first of a series, Bryce Gaton looks at the core part of the EV, its battery pack, and how to give it the longest possible life. In later articles, he will explain the options for testing and monitoring the battery pack in your EV.

WE ARE all familiar with the ways to prolong the life of an internal combustion engine (ICE) vehicle—regular service, monitor the oil, etc—but EVs are a whole new ball game. What do they need to maintain them in tip-top working order? And how can we test them to know if things are going wrong?

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While in general EVs need less maintenance than conventional cars, there are some considerations which will help keep the car performing well for longer and reduce maintenance costs. The battery pack is the component that is both the costliest to replace and the most within our control to keep healthy.

For example, for an ICE vehicle converted to battery electric, replacing the battery pack can cost from $110 to $300 per lithium cell with the battery pack size ranging from 30 to 100 cells—at a cost of $3300 to $33,000. For a Nissan Leaf, replacing the 24 kWh battery is around $6500 fitted (AU$ equivalent to US$ replacement cost—Leaf replacement batteries are not necessarily available here).

What is an EV battery pack made of?

All the pure EVs and hybrids on the market now use variations of a lithium ion chemistry. A common one is lithium iron phosphate, commonly written as LiFePO4. Lithium offers many advantages over previous battery technologies. In particular, it allows for much lighter batteries than lead-acid, which is what EV batteries used to be made from.

Lithium batteries can also be more deeply discharged, down to 20% capacity, giving more available energy to take you further; they hold a stable voltage through most of their discharge range (see graph); they can take high charge and discharge rates, allowing for hard acceleration and fast charging; and they are largely maintenance-free.

They should also have a long life, if looked after, with 70% to 80% capacity remaining in the battery after eight to ten years. And even after that, lithium EV battery packs are still usable in less demanding applications, such as home storage

Lithium cells have some features that need to be taken into account in the design of the car and charging systems. If they are overcharged or discharged (below 2.5V or above 4V), they will likely be destroyed (although LiFePO4 are more abuse resistant and may be recoverable). And, in some formulations, they can catch fire. This is particularly a problem for the super light, very energy dense ones in phones and the like: think Samsung Note 7. EV batteries are now made with formulations that are more resistant to starting or maintaining a fire.

To allow for these issues, modern EVs and hybrids include a battery management system (BMS). The BMS is a complex set of electronics that manages the charging of each cell, as well as controlling the current available to drive as the battery discharges.

Read the full article in ReNew 139.

fronius-hybrid-diag

Just add batteries

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There’s more to consider than just the brand or size when adding storage to a solar system. Damien Moyse and Nick Carrazzo highlight some of the issues to consider in a field with ever-evolving technology.

There are multiple ways that batteries can be added to an existing or new solar PV system. These different configurations will influence the system’s capabilities so it’s important to carefully consider the approach you take. This article covers the most common approaches currently available in Australia, but note that technology and options are developing rapidly so we will be updating this advice regularly.

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The majority of solar PV systems currently installed in Australia are unlikely to be ‘battery-ready’—an existing solar customer cannot simply purchase a lead-acid, lithium ion, flow or sodium battery and have it retrofitted to their existing system.

The solar panels can be retained, of course, but an additional or replacement inverter and charging components will likely be needed to charge and use the batteries.

One approach (DC coupling) involves replacing the existing grid-interactive inverter with a new hybrid inverter; such inverters can both control charging of the battery and conversion of electricity from DC to the AC required for household use. As a cheaper alternative, in a fairly recent development, the replacement of the grid-interactive inverter can be avoided through fitting a DC to DC converter between the solar array and the battery bank—thereby negating the need to replace the existing grid-interactive inverter.

A second approach (AC coupling) requires installation of a second battery-dedicated hybrid inverter (with integral charger controller), with the existing grid-interactive inverter retained.

As such, almost all the new battery products currently on the Australian market are either sold with a new inverter (some as part of an integrated ‘all-in-one’ storage unit and some with the inverter separate from the battery) or require an inverter to be purchased separately.

Thus, most existing solar customers will need to replace their existing grid-interactive solar inverter, add a second inverter or add a DC to DC converter to their system. Which approach is taken depends on whether the system uses AC or DC coupling and the capabilities required of the system. Coupling refers to where within the system the batteries are connected.

Read the full article in ReNew 137.

tassie-off-grid

Tassie off-grid home

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Given their distance from the nearest power pole, it made sense financially as well as philosophically for this Sydney couple to go off-grid in their new home in Tasmania. Peter Tuft describes how they went about it.

As we approached retirement my wife Robyn and I knew we did not want to spend the rest of our lives in Sydney. Sydney’s natural environment is glorious but it is also much too busy, too hot and humid in summer, and our house was too cold and hard to heat in winter. We had loved Tasmania since bushwalking there extensively in the 1970s and it has a lovely cool climate, so it was an obvious choice.

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We narrowed the selection to somewhere within one hour‘s drive of Hobart, then on a reconnaissance trip narrowed it further to the Channel region to the south. It has lush forests and scattered pasture with the sheltered d’Entrecasteaux Channel on one side and tall hills behind—just beautiful. And we were extraordinarily lucky to quickly find an 80 hectare lot which had all those elements plus extensive views over the Channel and Bruny Island to the Tasman Peninsula. It was a fraction of the cost of a Sydney suburban lot.

The decision to buy was in 2008 but building did not start until 2014 so we had plenty of time to think about what and how to build. We have always been interested in sustainability, and renewable energy in particular, even before they became so obviously necessary: my engineering undergraduate thesis in 1975 was on a solar heater and Robyn worked for many years on wastewater treatment and stream water quality. There was never any doubt that we would make maximum use of renewable energy and alternative waste disposal methods.

From the beginning we knew the house would be of passive solar thermal design. The house sits high on a hill (for the views!) and faces north-east. The main living room is entirely glass-fronted, about 11m long and up to 4m high with wide eaves. That allows huge solar input to the floor of polished concrete. A slight downside is that there is potential for it to be too warm in summer, but we’ve managed that with shade blinds and ventilation and so far it has not been a problem. All walls, floor and roof are well insulated, even the garage door, and all windows are double-glazed. Supplementary heating is via a wood heater set in a massive stone fireplace chosen partly for thermal mass and partly because it just looks awesome. Warm air from above the wood heater convects via ducts to the bathroom immediately behind the chimney, making it very cosy indeed.

Read the full article in ReNew 137.

powerwall

Australia’s first Powerwall home

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Nick Pfitzner and family are the proud owners of the first Tesla Powerwall home in Australia. Nick Pfiztner describes their configuration and the lessons they’ve learnt so far.

Our household had the privilege of the first Tesla Powerwall installation in Australia (maybe the world, they say). It has been a very interesting experience so far, and we’ve learnt a lot about what makes the house tick from an electricity point of view.  I’ve also had the opportunity to discuss the energy generation landscape with several organisations developing similar energy storage technologies.

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As a self-described Elon Musk fanboy, I became seriously interested in energy storage for our house after the Tesla Powerwall launch in 2015. I knew about other home storage systems, but mostly associated them with lead-acid systems and off-grid enthusiasts. We had previously got a quote for an off-grid AGM lead-acid system at one point, but we didn’t have the finance or space to make the BSB (big steel box) happen at that time.

However, by late last year with our finances more in order, we decided to take the plunge with the Powerwall. We chose Natural Solar as the installer. They had advertised themselves as the first certified installer of Powerwall in Australia and helped guide us through the options available.

We opted for 5 kW of Phono solar panels with a SolarEdge inverter and, of course, the Powerwall, for a total cost of $15,990 installed.

And add Reposit grid credits

Natural Solar also informed us about Reposit Power, a software package designed to maximise the benefits of home storage for the consumer. In a nutshell, Reposit is a software-based controller for the entire system. It learns the household usage patterns, gathers weather forecast data and interfaces with the inverter to make decisions about import or export of energy based on two important concepts:

Tariff arbitrage. This is the practice of switching to a time-of-use grid tariff and charging the battery at times advantageous to electricity pricing. This may occur when solar PV generation predictions for the next day are poor or where energy storage has been used up overnight. In either case, off-peak power can be imported for use the next morning.

GridCredits. This is an ARENA-supported project to investigate the use of intelligent storage and distribution of power via consumer-level battery systems, with the aim of reducing network infrastructure costs in future. Consumers are rewarded not through feed-in tariffs based on intermittent solar generation, but rather guaranteed power delivery from the battery. When the wholesale market for electricity is especially high, the electricity retailer discharges electricity from the battery into the grid, paying the consumer $1 per kWh.

These two factors could assist with the financial equation, so we figured it was worth the add-on cost of installing Reposit—an extra $800 at the time.

Read the full article in ReNew 137.

Renewable energy courses

Renewable energy courses guide

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We’ve updated our renewable energy courses guide ready for enrolment time. You’ll find the table of courses—from TAFE certificates to postgraduate degrees—here. In the article, Anna Cumming has a look at what’s new in the industry.

IN the two years since we last published a review of the renewable energy courses available in Australia, things haven’t all been rosy for the renewable energy (RE) industry. Months of uncertainty at federal level over the national Renewable Energy Target, funding cuts to climate-related science, and the scaling back of feed-in tariffs for solar generation have all contributed to a reduction in the size of the industry.

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The latest available Clean Energy Council (CEC) figures put the number of people employed in the wider RE industry at 14,020 for the financial year 2014–15, down a big 27% from the peak of 19,120 in 2011–121. However, the CEC puts some of this contraction down to a consolidation of the small-scale solar industry to more stable and sustainable levels. It also notes that RET legislation was passed right at the end of the reporting period, and since then confidence has grown: “The mood across the industry is upbeat in 2016, and it is expected that job figures will begin to grow once project development begins in earnest again under the RET in the coming years.”

David Tolliday, Renewable Energy Training Coordinator at Holmesglen in Victoria, shares this feeling. “The initial RE boom [homeowners taking advantage of rebates and premium feed-in tariffs to install solar PV] has passed, and the solar install industry has settled to around 4200 accredited installers—a good sustainable number,” he says. “The big opportunities now are in bigger-scale stuff like commercial solar, and battery storage on grid-connected systems.”

So, how to get involved? For those wanting to get into the industry or upskill, there is a wide variety of training and courses to choose from, from undergraduate and postgraduate university courses in engineering or focused on broader energy strategy, to hands-on solar design and install certificates offered by TAFEs and private registered training organisations (RTOs), and even free online MOOCs (massive online open courses). See our previous RE courses guide in ReNew 129 for a comprehensive look at the types of courses available, prerequisites and typical training pathways; here, we look at what’s new since 2014.

Download the table of renewable energy courses here (130KB).

Read the full article in ReNew 137.

battery-tech

The lowdown on battery technology

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Critical to any energy storage system is the battery itself. So what technologies are available and what are their pros and cons? Lance Turner takes a look inside the technologies available now and what’s in the offing.

IT SEEMS that almost every day a new domestic energy storage system is released onto the market. While manufacturers concentrate on the latest features like compatibility with existing systems, system monitoring, integrated inverters and even programmability, very little is mentioned about the actual storage medium itself.

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What makes one battery better than another for a particular use, and which technology should you be looking at for your energy storage system needs? Let’s look at the current options in a bit more detail, including advantages and disadvantages of each, and then look at some newer technologies available now that you may not have seen.

Lead-acid

This old faithful is the mainstay of the home energy storage industry. Lead-acid batteries have been in use for over a century and are a tried and proven technology.

They consist of plates made of spongy lead (negative plate) and lead dioxide (positive plate), with sulphuric acid as the electrolyte. During discharge, both plates are converted to lead sulphate, and the discharge reaction produces water which dilutes the sulphuric acid, changing its specific gravity. This change in specific gravity is what allows you to measure a flooded-cell lead-acid battery’s true state of charge using a hygrometer.

Lead-acid batteries have several advantages:

  • reasonable resistance to overcharging
  • lower cost than many other technologies
  • readily available
  • almost 100% recyclable
  • almost all inverters and charge controllers are lead-acid compatible
  • widespread knowledge of the technology in the industry.

They also have disadvantages, including:

  • low energy density, which means high weight per unit of storage
  • can’t be regularly deep cycled without reducing lifespan
  • primary reactive materials are toxic and corrosive
  • can produce explosive hydrogen gas when charging
  • can’t be stored partially discharged without damage—must be fully charged regularly to prevent sulphation (where permanent lead sulphate crystals form on the plates)
  • Peukert effect—effective capacity reduces with increasing discharge rate.

The full article looks at currently available battery technologies in detail, including:

  • lead-acid
  • lithium ion
  • flow
  • salt water
  • metal-air
  • molten salt

Read the full article in ReNew 137.

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Finding value in sharing

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Can we find value for both customers and the network in sharing locally generated energy and thus accelerate a transition to 100% renewables? Bruce Thompson and Paul Murfitt discuss the potential in microgrids, virtual power plants and more.

The transformation of the electricity network is certainly now upon us. Years of environmental advocacy, rapid technology advances and shifts in consumer demand are driving an unprecedented shake up of our century-old supply network. With this change come opportunities (and some risks) to harness the value of renewable energy across the grid as we drive towards zero emissions.

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Traditionally, Australia’s electricity networks were largely built and controlled by state governments, and operated as central power supply systems managed with two policy imperatives in mind: security of supply and cost-effectiveness. The much-heralded disruption is turning this system upside down, bringing technical and financial challenges along with opportunities.

The big shift to date has been ‘behind the meter’, where there is a clear case for householders and businesses to invest in solar PV to avoid the cost of conventional energy supply. Yet establishing value ‘in front of the meter’—sharing your locally generated energy across the grid—has so far been fraught.

With the tapering off of feed-in-tariffs, owners of solar have been frustrated they don’t receive a fair price for their homegrown generation. On the other side of the fence, network operators have been aggrieved by the need to manage the technical impacts of solar PV and wind while their business model ‘death spirals’ from lower consumption.

Beyond the angst, new models such as microgrids and virtual power plants are starting to demonstrate that sharing solar PV generation and battery storage across the grid can leverage the opportunities and help manage the risks inherent in Australia’s changing electricity sector. For customers, potential benefits include access to wholesale pricing and retail tariffs. For networks, there can be lower costs from local control and load management, particularly if the models can reduce peak demand and avoid the need for network infrastructure augmentation.

Of course, the value of sharing locally generated energy across the grid is dependent on the time of day, the time of year and the location. The key challenge for ‘in front of the meter’ solutions is not only to understand the technology, but also to apply the fundamental principles of supply and demand to determine where the greatest value can be realised.

Bruce Thompson recently joined GreenSync as the Community Development Director following 12 years at Moreland Energy Foundation Ltd (MEFL) as major projects director. He is also the outgoing chair of the Coalition for Community Energy (C4CE). Paul Murfitt was recently appointed director of energy efficiency for the Victorian Government and is the outgoing CEO of MEFL.

Read the full article in ReNew 137.

mooroolbark

Neighbourly sharing: mini-grid in Mooroolbark, community battery in WA

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Neighbours in the Melbourne suburb of Mooroolbark are set to share their energy generation via a mini-grid in an Australian-first trial run by AusNet Services. Eva Matthews finds out what’s involved.

IN AN Australian first, network provider AusNet Services is currently rolling out a solar + storage mini-grid trial in Mooroolbark, in Melbourne’s east.

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Of the 16 homes on the chosen street, 14 will each have between 3 and 4.5 kW of solar panels and a 10 kWh battery storage system installed, with a cloud-based monitoring and management platform to optimise power flows across the mini-grid and to provide demand management support to the network.

The two-year trial was announced in April and was made possible with funding from the Demand Management Innovation Allowance. Participants don’t pay for the equipment and, at the end of the trial, get to keep their panels and inverter (but the control system and battery storage go back to AusNet Services).

As at end August, all houses have solar panels, inverter and battery storage installed, enabling data gathering on energy generation and usage patterns. The control system should be in by end October, which is when testing can begin in earnest. Testing will include deciding when to charge and discharge the batteries, and at what rate, based on current and forecast customer usage and PV generation as well as the network requirements. A single objective (e.g. minimising the overall peak demand on the mini-grid) can be implemented in a number of ways, so they will be developing and testing different approaches. The stabilising device and switching equipment that enable the mini-grid to be islanded (isolated from the rest of the network) will be installed towards the end of this year.

The group of houses will operate as a mini-grid from a control and electrical point of view, but the metering and billing arrangements are unchanged. To enable financial offsetting of one participant’s generation against another’s usage would require different meters to be installed—with a parent meter for the mini-grid and sub-meters for each house—so instead they will be modelling the potential financial effects.

Two households were unable to participate in the trial; however, this will provide fortuitous real-world data for where there is less than 100% opt-in—testing how the mini-grid can serve the energy needs of these houses without having their energy contribution in the mix. AusNet Services’ Distributed Energy and Innovation Manager Justin Harding explains, “Those houses will simply appear as extra loads in the mini-grid. For example, if we are trying to reduce the net demand of the mini-grid to zero at the connection point to the main grid, all houses would need to export a small amount of energy to offset the non-participants’ load.”

Simone and Joel Beatty make up one of the households participating in the trial. When they purchased their home five years ago, Simone says they noticed that a lot of the new houses being built were having solar installed, and it was something they were interested in, but hadn’t been able to afford. So when AusNet Services came knocking on their door with news of the trial, Simone says they were “definitely excited.” As well as looking forward to seeing how it all works, and the impact on their electricity bills, Simone says they have also benefitted from the information provided by AusNet Services—how they can log in to a web portal to monitor their electricity usage and ways in which they can be more energy efficient. She says they have “definitely already altered some behaviours.” And not only has there been an educational side effect of having the technology installed, it has given the neighbourhood something in common to talk about and get excited about. Simone says “everyone seems very positive about it” and adds that friends and family are jealous!

This trial follows a three-year battery storage trial by AusNet Services that tested how residential batteries can reduce customer’s maximum demand for electricity and support the network. Justin Harding says that there will likely be an “evolution of trials” into the future. This Mooroolbark trial has a strong customer learning and technical focus; the next step could be a larger project with more of a commercial focus, looking at how best to structure finances and customer agreements.

Tech used in Mooroolbark mini-grid:

  • 3 kW of panels (JA Solar) per house, except where customers had existing PV systems
  • 10 kWh lithium ion battery storage (LG Chem) per house
  • 5 kW battery inverter (Selectronic
    SP Pro) per house
  • Peak Response Unit (GreenSync) per house—a communications device for optimising power flows, includes 3G modem that talks to the main control system and battery inverter
  • cloud-based control platform (GreenSync’s MicroEM)—runs forecasting/optimisation calculations to enable locally generated/stored energy to be shared between homes, based on the needs of individual houses and the needs of the mini-grid
  • a separate 3-phase inverter and Toshiba battery system from Power Technology to keep the mini-grid stable when in islanded mode
  • switching cabinet with circuit breaker and protection relay to transition the mini-grid to/from the main grid, supplied by EIV.

Aims/benefits of the trial:

  • test how mini-grids can support the network, e.g. to better manage peak demands, reduce risk of system overload, defer capital expenditure
  • optimise value of the assets both for customers and the network, e.g. getting full value from battery storage when customers are grouped and there is one overriding control system versus single households exporting/importing energy to/from the grid
  • better understand household generation and usage patterns to help determine payment structures and tariffs, and test how energy self-sufficient a community can be
  • test potential for an uninterruptible power supply, i.e. where homes can be islanded, either individually or as a microgrid, and stored energy used if the grid goes down
  • investigate the performance of new methods to identify and mitigate electrical faults in a 100% inverter-based supply environment.

Best of both? Community battery trial in WA

A CUTTING-EDGE residential battery trial underway in the new Perth suburb of Alkimos allows residents to generate solar electricity and benefit from access to a ‘virtual storage’ battery system.

Led by local energy provider Synergy, in collaboration with Lendlease and LandCorp, the project involves a utility-scale grid-connected 0.5 MVA/1.1 MWh battery energy storage system located on-site in two shipping containers.

It has a number of aims: to reduce energy bills for participating households and improve network efficiencies by ultimately reducing connection costs. However, the most interesting and important aspect of the trial is Synergy’s ‘time of use’ billing product called the Peak Demand Saver plan.

The plan works by offering a three-part tariff for network energy, with different energy charges for peak daily (4 pm to 8 pm), off-peak day (midnight to 4 pm) and off-peak evening (8 pm to midnight). The time-of-use energy tariffs are designed to encourage households to minimise consumption and maximise returns on their solar PV investment—but without the need to invest in their own battery storage.

This new-style product means Alkimos residents pay a fee each month to have access to the community-scale battery storage. Those who store solar credits during the day draw on them first during the peak daily period, and then for the evening off-peak without incurring any additional costs, in much the same way they would their own battery.  During the day households use their own solar energy.

“It’s everybody’s battery to use. Customers pay $11 per month to use it, and then we calculate their usage over a 60-day billing period,” said Synergy.

“Anything they put into the batteries is theirs to draw on at peak times at no additional charge. And whatever they have left in the battery after the 60-day billing cycle is purchased from them at a 7 cents per kWh [feed-in tariff] rate. Because it is ‘virtual’ storage you can pretend it is your own battery, it’s just your neighbours are pretending it’s their battery too.”

So far, 65 residents have opted to participate in the trial since it began in April 2016 with the aim that 100 households will take part over the four-year trial period. Before residents join the trial, Synergy analyses their historical consumption to ensure the tariff suits their usage patterns.

“However, we’ve already had customers who want to participate even though they are not necessarily going to be better off, because they want to be part of the first shared battery trial in Australia,” said Synergy.

The trial will cost around $6.7 million and is backed with a $3.3 million Australian Renewable Energy Agency grant, and when launching the trial ARENA CEO Ivor Frischknecht said community-scale battery storage held great promise. “A new [housing] development like this might actually need less of a connection, or a smaller connection [to the electricity network]. That means lower costs for those people that are buying new lots and less investment into poles, wires and transformers,” he said.

For more info: www.synergy.net.au/Global/Alkimos-Peak-Demand-Saver-plan

Read more on microgrids in ReNew 137.

raygen

Solar sells: Australian PV research and innovation

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From PERCs to heliostats to improving PV quality, Andrew Blakers from the Australian National University describes high-impact innovations that found their way through Australian-led, government-supported research.

Through consistent government grants for innovation over the past 40 years, Australia has punched far above its weight in renewable energy innovation, particularly when it comes to photovoltaics (PV). The potential benefits for the Australian economy are substantial. PV now constitutes about a quarter of new electrical generation capacity installed worldwide each year; wind comprises another quarter; and coal, oil, gas, nuclear, hydro and all other renewables combined constitute the other half. In Australia, PV and wind comprise practically all new generation capacity.

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Support for research and innovation lies at the heart of accelerated growth of the renewable energy industry. It supports later-stage commercialisation directly through technology development. Additionally, university research groups underpin undergraduate and postgraduate education and training of engineers and scientists.

High-impact Australian innovations
What are some of the ways Australia has contributed to solar research, and what are some of the commercial successes? Here are eight examples of high-impact innovations that emerged from Australian-led R&D.

1. PERC SOLAR CELLS
The PERC silicon solar cell is an Australian invention which is now used in about half of new solar cell production lines worldwide. It’s set to soon dominate the worldwide solar industry, according to the International Technology Roadmap for Photovoltaics. So far this is the most successful renewable energy technology to emerge from Australia.

2. PHOTO-LUMINESCENCE
BT Imaging’s advanced photo-luminescence characterisation systems for research and industry emerged from the University of NSW. They enable researchers and industrial engineers to visually assess silicon quality in great detail and to modify processes to maximise quality.

Read the full article in ReNew 136.