In ‘Solar’ Category

142 Front cover 150dpi full size

ReNew 142 editorial: to boldy solve the split incentive

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THERE are some great landlords out there, providing comfortable, energy-efficient housing for the 31% of Australians who rent. But there are also many cases of poorly maintained and poorly performing rental properties. With New Zealand bringing in minimum standards for energy efficiency measures such as insulation, it’s time for Australia to step up. The states have some schemes in place, but much more is needed, including incentives and regulations.

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We look at what’s happening in Australia, what landlords can do (and what some are doing already), and the energy efficiency scorecard currently being trialled in Victoria that may help push the market in the right direction.

Another area where renters often miss out is the savings that come from solar. The same goes for apartments, where it can be difficult to install solar for many reasons, including technical. But both markets can and are being catered for. We look at what’s possible to solve the solar ‘split incentive’ and look at case studies of solar panels making their way on to this under-used rooftop resource: a win for landlords, renters and the environment.

Our buyers guide this issue is on solar panels. Although many ReNew readers may already have systems, there are still many rooftops without solar (including rental ones), and many readers may be looking to add a larger system to their existing one. We also follow one person’s story of their recent solar install: how they did their research and sizing, and the process from accepting the quote through to receiving a feed-in tariff for their homegrown clean energy.

Over the past year, the ATA has been advocating for a transition to a 100% renewable grid for Australia. Andrew Reddaway’s report from last year asked if it was possible (answer: yes, and by 2030). This time he investigates how Australia is progressing. It seems that a clear transition is underway, with many projects in the pipeline, all renewable. But it requires proper planning, which has been lacking to date. Andrew’s work shows just what a plan might look like. It’s inspiring, and maddening at the same time: it’s affordable and possible to do this within 13 years, yet we are sitting around debating whether we should allow Liddell to close or not.

There’s much more in the issue besides. We look at PV recycling, present an induction cooktop mini guide and give an update on the growing (at least elsewhere) EV market. Beyond solar PV, Tim Forcey argues that we all need to become familiar with the term ‘renewable heat’. As he says, in his home, just 20% of his home’s renewable energy comes from solar—the other 80% comes from heat from the air, used by his hot water heat pump and air conditioner.

We hope you enjoy the issue. The ReNew team wishes everyone a relaxing and safe holiday period and we look forward to hearing from you in the new year.

Robyn Deed
ReNew Editor

ATA CEO’s Report

In Australia, renewable energy and carbon emission targets are again being used as a political football, in which there are no winners. In fact, it’s hard not to feel that each time we take two steps forward with action on climate change, we also take three steps back.

However, despite community frustration with political leadership in this area, there are positive stories to tell. The momentum for a low-emissions future grows apace with the price of renewable energy continuing to fall—it is now cheaper to develop solar and wind energy than new coal-fired power stations in most countries. And we have industry leaders calling for certainty on energy policy so that they can get on with the job.

The good news is that the knowledge, technology and solutions to enable households and communities to reduce their carbon emissions and save money are available.
With electricity prices continuing to rise, new technologies such as batteries and heat pumps coming on to the market and more Australians wanting to take control of their energy future by producing their own renewable energy, there is a need more than ever for quality, independent information for households. That’s where the ATA and our commitment to providing quality independent advice comes in, most recently with our free online solar & battery sizing tool. Find it at www.ata.org.au/ata-solar-advice.

At the ATA every year we are helping hundreds of thousands of people make a practical difference and we’ll keep doing this through 2018. Thank you to all our members, partners and supporters who are part of our community of change.

Donna Luckman
CEO, ATA

You can purchase ReNew 142 from the ATA webshop.

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Solar panel buyers guide 2018

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We’ve contacted photovoltaics manufacturers for details on warranties, cell types, size and price to help you decide which solar panels are best for you.

Solar photovoltaic (PV) panels have become a common sight in the Australian urban landscape. From powering domestic dwellings to providing power for camping or even hot water, PV panels are everywhere. In Australia there are around 1.7 million rooftop solar installations, totalling over 5.6 GW of installed capacity.

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However, there are still many homes without solar. This article aims to provide guidance for those looking at purchasing a solar installation, whether a new system or an upgrade. It includes types of solar panels and factors to consider when buying them. The guide focuses on PV panels only. For information on other components that may be used in a solar installation (e.g. inverters), system sizing and economic returns, see ‘More info’ at the end of the article.

Solar panel types: monocrystalline, polycrystalline and thin film
Solar panels are made from many solar cells connected together, with each solar cell producing DC (direct current) electricity when sunlight hits it. There are three common types of solar cell: monocrystalline, polycrystalline and thin film. There are very few thin-film panels on the residential PV market—most panels are of the crystalline type.

Both monocrystalline and polycrystalline cells are made from slices, or wafers, cut from blocks of silicon (one of the most common elements on Earth). Monocrystalline cells start life as a single large crystal known as a boule, which is ‘grown’ in a slow and energy-intensive process. Polycrystalline cells are cut from blocks of cast silicon rather than single large crystals.

Thin-film technology uses a different technique that involves the deposit of layers of semiconducting and conducting materials directly onto metal, glass or even plastic. The most common thin-film panels use amorphous (non-crystalline) silicon and are found everywhere from watches and calculators right through to large grid-connected PV arrays. Other types of thin-film materials include CIGS (copper indium gallium di-selenide) and CdTe (cadmium telluride). These tend to have higher efficiencies than amorphous silicon cells, with CIGS cells rivalling crystalline cells for efficiency. However, the materials used in some of these alternatives are more toxic than silicon—cadmium, particularly, is a quite toxic metal.

Each cell type has some advantages and disadvantages, but all in all, modern solar panels do pretty much what they are designed to do. There are no moving parts to wear out, just solid state cells that have very long lifespans.

Crystalline cells are a very mature technology and have a long history of reliability, so a good quality crystalline PV panel will very likely perform close to specifications for its rated lifespan, which is 25 years or more for most panels. Crystalline panels are usually cheaper than thin-film types, with the cheapest being polycrystalline panels, although the pricing gap between cell types has diminished in recent years.

Read the full article in ReNew 142

Click here to download the full buyers guide tables in PDF format.

north-facing array

Getting solar: from research to install

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Getting solar may be common, but when you’re doing it for the first time it can be a bit of a mystery. Stephen Zuluaga explains his research to get the best system for his house.

UNTIL recently, I’d thought solar wouldn’t work well on our house. With little north-facing roof to speak of, I just assumed that solar wouldn’t be worth it. But then I began to read about some of the good outcomes possible with an east/west array—our roof has lots of east/west space and shading issues only at the extreme ends of the day.

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Although an east/west array will produce less overall than a north-facing one, it can extend generation hours, both earlier in the morning with an east-facing array and later in the day with a west-facing system. Long generation hours are important if you don’t have battery storage and the gravy train of premium feed-in tariffs has left the station. It means you can match more of your generation to usage, particularly before and after work usage, and hence increase your ‘self-consumption’ of solar—this will mean lower grid imports and a shorter payback period.

Modelling the economics
Before committing to a solar purchase, I was interested to more fully understand the financials. I found ATA’s free Sunulator tool (www.ata.org.au/ata-research/sunulator) which helped me model a scenario based on my actual electricity consumption and the combined north/east/west PV configuration I was contemplating. Sunulator is a great tool—if you’re planning solar you should use it. [Ed note: ATA also has a simpler tool available to give you an indication of the financials without the full modelling of Sunulator, see www.ata.org.au/ata-solar-advice.] The energy analysts at the ATA helped with understanding the Sunulator results as one of the ATA member benefits.

Read the full article in ReNew 142.

Stucco apartments solar system

Solar for renters and apartment dwellers

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Renters and residents of strata complexes have traditionally struggled to access solar. Dr Björn Sturmberg and Anna Cumming report on how these groups can join the solar revolution.

IN AUSTRALIA, we have an ‘energy trifecta’ of famously abundant sunshine, infamously high electricity prices and efficient solar supply chains. It’s no surprise then that Australians have embraced the option of rooftop solar systems at record rates. By September this year we’d collectively installed over 1.7 million solar systems, and in Queensland and South Australia every third house is solar powered. Forecasts all agree that the solar boom is far from over, particularly now that the advent of affordable household battery systems is fuelling the divergent dreams of either becoming a ‘gentailer’ (generator–retailer) of your excess solar power in a peer-to-peer network, or defecting from the grid entirely.

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While the growing ubiquity of solar is a wonderful outcome environmentally, socially it is causing tension between the ‘solar haves’ and ‘solar have nots’. To be clear, the solar haves are in fact saving all Australians money on their electricity bills1 through their supply of excess solar power to the wholesale market at times of high demand. Still, the cheapest source of electricity for the Australian home is behind-the-meter solar and those who cannot access this are being left behind to bear the full burden of skyrocketing electricity prices.

One main reason for being locked out of solar is not owning your own roof. Renters and apartment dwellers make up more than one in three Australians and have traditionally struggled to access solar; the grid is also missing out, as all those roofs represent significant untapped solar potential. Happily, the demand is there, and options are emerging even for these tricky market sectors.

Read the full article in ReNew 142.

Linnet Good MASH customer 600px

Sharing the solar benefits: case studies

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If you don’t own your own roof, how can you get solar? We speak to a variety of tenants and apartment owners to see how they went about it.

Doing a deal with the landlady
Originally hailing from Sydney, Dev Mukherjee found winters in his poorly insulated rented sharehouse in Castlemaine, central Victoria, pretty hard to handle. Although from Melbourne, his partner Linnet Good also felt the cold, and she worked from home. The all-electric house also incurred large electricity bills—up to $800 per quarter in winter for the three tenants, as they only had a single reverse-cycle heater in the living area and used plug-in radiators elsewhere.

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After living there for a couple of years, and prompted by a bulk-buy solar scheme offered by local sustainability group Mount Alexander Solar Homes (now More Australian Solar Homes), Dev and Linnet approached their landlady about installing solar on the property in an effort to reduce their energy bills as well as the house’s environmental impact.

“Our landlady was supportive,” says Dev, “though of course she was concerned about the cost. She wanted to ensure she’d recoup the cost while the system was still under warranty. The panels had a ten-year warranty, but the inverter was only warranted for five years.” Eventually a suitable agreement was reached, and in spring 2014 a 3 kW solar system was installed at a cost of around $5000.

The electricity bill remained in the tenants’ names after the solar system was installed, and they retained the feed-in tariff for exported solar generation. They negotiated a $25 per week rental increase with their landlady, calculated to pay back the cost of the solar system over five years. “Our average bill reduction we calculated to be slightly more than $25 per week,” he says, helped by changing their behaviour to make best use of the solar, like running the washing machine in the middle of the day.

In addition, they didn’t have another rent increase in the time that they lived in the house. (In the end, despite intending to stay long term, they moved out as the landlady wanted to sell the property vacant; Dev believes the solar system was a drawcard for the purchasers.)

Dev and Linnet encourage other renters to start a conversation with their landlords about installing solar. “It helps if you have a good relationship with the owners, and be mindful that, as they put up the capital, they must be able to see a return on that investment.”

Read more case studies in ReNew 142.

Sheep roam seven hectares on the UQ Gatton solar farm

100% renewable by 2030

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In late 2016, we reported on ATA analysis that showed a 100% renewable grid is feasible and economic in the long-term. Here, Andrew Reddaway follows up to see how we’re progressing towards that goal.

The last year has seen much action in the electricity grid, both announced and commenced. It’s become clear that the electricity grid’s transition is well underway, as coal-fired power stations are being replaced by renewables. However, poor planning and coordination has caused problems such as curtailment of wind generation in SA.

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Transition planning needed
As the grid transitions to a high level of renewables, good long-term planning is required. If the grid’s current planning arrangements continue unchanged, decisions and investments will be uncoordinated. They may make sense for the short-term profits of individual companies, but may not lead to a well-designed overall system. The Chief Scientist considered this, and recommended an “integrated grid plan” by the Australian Energy Market Operator (AEMO).

In the current system, generators compete against each other, may close without notice and have a business incentive to conceal their future intentions.

There is no guarantee that new power stations will be built—the system expects that investors will foresee a shortfall, identify a profit and construct the needed infrastructure. To assist investors, AEMO annually produces the Electricity Statement Of Opportunities report attempting to identify future shortfalls. This document only looks ahead 10 years, and doesn’t consider scenarios such as 100% renewables. AEMO also produces a transmission report, which looks ahead 20 years but has a relatively narrow focus on transmission lines and related assets.

In hindsight this system has a clear flaw. If investors fail to act in time, generating capacity may be insufficient to meet demand. It takes several years to build a new power station, but an old one can be closed very quickly—Hazelwood’s owners provided only five months notice. Individual asset owners have no responsibility for overall system reliability.

This is why interventions in the market have been required in 2017, including the SA government’s Energy Plan.

The current system also relies heavily on clear, long-term government policy to guide investors. Without such policy, investors face the risk that their newly-built asset might have to contend with unexpected new incentives, rules and regulations.

The best plan so far
In the absence of long-range planning by authorities for a high-renewable grid, the best studies have come from universities. In February 2017, the ANU published a clear vision for our future grid. Its researchers found the most economic combination for a fully renewable grid comprises:

  • wind farms (45,000 MW)
  • solar farms (23,000 MW)
  • rooftop solar (17,000 MW)
  • existing hydroelectric and biomass generators (10,800 MW)
  • pumped hydro energy storage
  • extra transmission lines.

Read the full article in ReNew 142 or you can find the paper on which the article is based at www.ata.org.au/news/100-renewable-energy-by-2030.

Solar panels waiting to be recycled

PV recycling

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What do you do when a solar panel comes to the end of its useful life? Moreover, what do you do with billions of them? Eva Matthews investigates.

From its infancy in the 1980s, solar as a source of renewable energy has finally become mainstream. In Australia, installed solar capacity has grown from 0.13 GW in 2010 to 6.2 GW as at mid-2017—a 4500% increase. Globally, in the same timeframe, capacity has grown from 50 GW to 305 GW. Fantastic!

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Assuming that today’s panels are typically 270 W to 300 W, this equates to a current global total of at least 1.1 billion panels—and given the early panels were just 60 W, this number is likely to be higher in reality. That’s a mind-boggling figure! And it’s only going to get bigger, with global installed capacity projected to reach 4500 GW by 2050.

At some point (let’s assume 25 years, the standard warranty period), all of these panels will come to the end of their useful lives … and then what? Given a standard panel weight of 18 kg, that’s roughly 20 million tonnes of potential waste to manage.

Panels may also be retired before the 25 years is up. Leaps in technology may lead to systems being upgraded early and a significant number of panels (roughly 10%) fail early due to damage during manufacture, transport or handling.

Trash and treasure
Unless properly managed, all this potential waste becomes a monumental problem. To date, unusable solar panels have often ended up in landfill, along with many thousands of tonnes of electronic waste (e-waste) despite programs to divert the waste for recycling.

PV panels contain small amounts of hazardous substances. These will only leach out if the panels are broken up—unfortunately, this is pretty much guaranteed to happen when they are deposited in landfill. In small amounts, the toxicity may be negligible, but when you’re talking millions of tonnes of panels, the danger of contamination is a significant concern. Silver, tin and lead (particularly in older panels) are the hazardous components of mono- and polycrystalline silicon panels (estimated at 50% to 60% of the market); indium, gallium, selenium, cadmium, tellurium and also lead are found in thin-film panels.

Currently 85% to 95% of a panel can be reclaimed and recycled. Some damaged or early-fail panels can be repaired and resold on the secondhand market or to developing countries at reduced prices, allowing access to solar technology to those who might otherwise not be able to afford it. Glass, copper, lead, aluminium and the hazardous semiconductor materials can be reclaimed through a mix of mechanical and chemical processes that have relatively low environmental impact, and either melted down for recycling or sold on as raw materials to be used in the creation of new solar panels and other electronics, reducing the embodied energy going into their manufacture.

Not only does the reclaiming/recycling approach make environmental sense, it’s worth big money. The most recent reports place the value of the global yield of recovered raw materials from solar panels at US$450 m by 2030, and in excess of US$15 b by 2050.

Thankfully, as a result, a PV recycling industry has emerged.

Read the full article in ReNew 142.

Grid voltage corrected infographic

Renewables improving the grid

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An innovative trial is using smart solar inverters on homes, both on their own and combined with batteries, to improve grid stability. By Lance Turner.

Many Australians are all too aware how unstable the electricity grid can be at times, especially under large loads, such as when everyone gets home and cranks up the air conditioner on a hot day. Other factors that can affect local grid stability can include large numbers of distributed generation sources (such as home PV systems) in a small area, long grid distribution lines, and old, poorly maintained or undersized grid equipment such as transformers and cables.

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The result can be a number of problems (see Figure 1), including low or excessive grid voltage, low or high grid frequency or poor power factor (a mismatch of the voltage and current waveforms).

While upgrading grid equipment is one possible solution, it’s not the only answer. Long feeder lines experience both increases and decreases in voltage along the line due to the natural impedance (like resistance) of the cables—homes a long way down the feeder can see an ohm or more of impedance between the substation and the home.

At times of light load (energy consumption) but high PV generation, such as the middle of a sunny weekday, the feeder may see a steadily increasing grid voltage along its length; for each ohm of impedance along the feeder line, every amp flowing into the grid raises the voltage on the grid by 1 volt. For example, each 5 kW solar system can be adding 20 amps into the grid, or an increase of up to 20 volts above the other end of the feeder line. In the evening when solar generation is almost zero but demand is high, this same grid impedance causes the voltage to sag. Thus, the voltages along the feeder, especially towards the far end, can vary widely (see Figure 2).

A good example of how extensive the problem can be is in Figure 3, which shows the high and low grid excursion events (where the grid voltage tends towards the allowable limits) for a selected substation over a two-year period.
Although this can be mitigated by an increase in cable size to lower resistance and installing transformers with a higher capacity, such upgrades are expensive and can never eliminate voltage variation caused by system impedances. So, other, smarter options are now being considered.

Read the full article in ReNew 142.

Australia's largest solar car park at USQ

Australia’s largest solar car park

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A solar car park just makes sense, particularly at a university campus where it can be used for research and education. A recent ATA branch meeting heard about the largest one in Australia, recently installed at USQ.

It’s inspiring to see renewable energy projects springing up in Queensland even in areas of significant fossil fuel production. One such example is Australia’s largest integrated solar car park, which is now operating at the University of Southern Queensland (USQ) in Toowoomba in the Darling Downs. This is a rich agricultural region that is also home to coal mining, coal seam gas production and two of the country’s youngest coal-fuelled power stations, alongside large solar (2 GW) and wind farm (500 MW) proposals—a region with very diverse business interests.

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The solar car park is part of a bigger project at USQ, the Sustainable Energy Solution, which involves installation of significant PV arrays around the university: a 1 MW car park solar array at the Toowoomba campus, 196 kW of rooftop PV at Ipswich, 205 kW of rooftop PV in Springfield and another 506 kW of rooftop PV in Toowoomba. Quite a feast of solar!

The solar project is intended as a feast for research as well. Andreas Helwig, a sustainable energy researcher from the school of mechanical and electrical engineering, is undertaking several research projects using the resulting “100 km virtual aperture” (i.e. modelled like 100 km of solar panels!) to investigate the “secret life” of solar panels. With PV across three locations, the research will investigate how solar cell performance is affected by transient clouds, varying levels of relative humidity and different types of airborne dust (including coal dust). All of these can degrade the PV output, reduce the cooling benefit of inverter heat sinks and exacerbate PV manufacturing faults.

Andreas notes, “A big question—and an expensive one—is when is it necessary to clean and maintain the surfaces of the arrays and the inverter heat sinks?” Research projects are also using infrared photometry to identify PV faults, whether from manufacturing or degradation over time.

Read the full article in ReNew 142.

monitoring_guide_phone

Knowledge is power – Energy monitoring guide

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Need help getting the upper hand on your electricity bills or checking that your solar system is working? You should consider an energy monitoring system, says James Martin from Solar Choice.

DO YOU have a clear picture of what’s drawing electricity in your home right now? If you’re like most Australians, you probably don’t.

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Historically, this hasn’t been an issue because electricity bills weren’t a major concern for most households and, in any case, the number of devices was probably small. But these days electricity prices are high and there are likely to be more electricity-consuming devices plugged into the walls of any given home than the occupants can think of off the top of their heads.

Many Australians have turned to solar panels to help them fight rising prices. Rooftop solar is now affordable and commonplace — the Hills Hoist of the 21st century.

However, comparatively low solar feed-in tariffs in most places mean that solar homes have less incentive to send solar electricity into the grid and more incentive to use it directly. Despite this fact, many (if not most) solar system owners would be at a loss if you asked them how much energy their system produced yesterday, never mind the proportion that they managed to self-consume.

Solar systems have even failed without the homeowner realising until they received their next bill. So monitoring is important!

Types of energy monitoring and management systems
Thankfully, there’s a growing number of products on the market that shed light on household energy consumption and solar generation. These devices take a range of approaches and offer a range of functions, but can generally be classed as either monitoring systems or management systems.

As the name implies, a monitoring system enables the user to ‘see’ what’s happening with their electricity, usually via an app or web-based portal, whereas a management system lets them not only observe but also ‘reach in’ and control which devices switch on at what times.

In reality, the line between the two is becoming increasingly blurred as platforms that once offered only monitoring get upgraded to let them do more.

Monitoring and management systems can be lumped into roughly five categories based on how they are physically installed in the home.

Read the full article in ReNew 141.

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.

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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.

An all-electric home can reduce your bills and ‘green’ your energy use, particularly if you run your house from the sun. And, as the grid gets greener, so too does your house. The roof of this Hawthorn, Melbourne extension was designed specifically to house the 4.5kW solar array that powers the house. Design by Habitech; read the full profile in Sanctuary 37.

Three steps to all-electric

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Thinking about going all-electric, but unsure what’s involved? Here we present an overview of the steps to going all-electric and where to find more information.

IN THE past, gas was seen as a cheap and clean option for winter heating, hot water and cooking. However, the efficiency of electric appliances has improved dramatically and solar PV has fallen so much in price (and can be used to power those appliances), meaning it can now be cheaper and more environmentally sustainable to go off gas and run an all-electric home.

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The ATA first looked at this in 2014 and the modelling results can be found at www.bit.ly/ATA-GVE. In summary, the results showed that even when paying grid electricity rates (i.e. without solar PV), for many Australian homes it would be cheaper over 10 years to switch from gas to efficient electric appliances, with appliances replaced as they fail or in some cases even before this. Greater savings can be found when disconnecting completely from the gas network as this eliminates the gas supply charge (costing several hundred dollars a year). The report also highlighted that new homes should not be connected to gas, as doing so would lock in higher energy costs than needed.

Savings will depend on the thermal performance of your home, the electricity price negotiated with your retailer, your gas tariffs and the efficiency of your appliances. The Grattan Institute found that a large home in Melbourne can save $1024 per year by disconnecting from the gas grid: www.bit.ly/GATCAHC

In addition, by using modern electric appliances, your home can be converted to use 100% renewable energy, whether you generate your own electricity with rooftop solar or purchase 100% GreenPower from your electricity retailer. The ATA’s latest modelling compares gas running costs to electric with solar; see p. 44 for preliminary results.

Three steps to all-electric

There are three main areas where many homes currently use gas: space heating, hot water and cooking (mainly cooktops, but ovens too). To switch to all-electric, there are now efficient options available for these uses. This article summarises the options and points to where to find more information.

Read the full article in ReNew 140.

Capture

Solar sizing: big returns

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Why it’s now advisable to ‘go big’ when installing a solar system, even if you don’t use much electricity: Andrew Reddaway presents the latest ATA modelling.

Many people ask us what size grid-connected solar system they should get. Traditionally, the ATA (ReNew’s publisher), has advised people to consider this carefully. If you primarily want to help the environment and cost is of little concern, it has always made sense to install as many panels as possible, as all their generation displaces electricity from dirty, centralised power plants. But most people have budgetary constraints, so their solar system needs to make economic sense as well as help the environment. To achieve this, we’ve previously recommended that people size a solar system based on their electricity consumption and maximise their other opportunities, such as energy efficiency. However, things have changed.

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Two big changes

1. Solar system prices

The last five years have seen significant price reductions, especially for larger solar systems. Prices vary with component quality and location, but on average a 5 kW solar system now costs around $6200 according to Solar Choice’s residential price benchmark data.

Let’s compare a 5 kW system to its smaller 2 kW cousin. To compare two different system sizes, the cost is presented in dollars per watt. Figure 1 reveals that since August 2012, the larger systems have halved in price, while the smaller ones have dropped by only a quarter.

Larger systems have always enjoyed economies of scale compared to smaller systems, because while the installer is on the roof it’s relatively easy for them to add more panels. One difference now is that the price of solar panels has fallen faster than other components. The industry has also become more familiar with larger systems, as they are now more frequently installed than small ones.

2. Feed-in tariffs

The Victorian government recently announced that solar feed-in tariffs will rise to 11.3 c/kWh from 1 July 2017, roughly double their previous level, and IPART has recently recommended a similar change in NSW. These changes are primarily due to wholesale electricity prices in the eastern states roughly doubling over the past year to around 10 c/kWh. We expect other states to follow suit, as feed-in tariffs below the wholesale electricity price are clearly unfair to people with solar. (In WA, a similar rise in wholesale rates hasn’t occurred, but prices might still rise due to the state government winding back its subsidy of electricity prices.)

What this means for solar system sizing

Given these changes, if you’re planning a solar system, is it worth it to upsize from, say, 2 kW to 5 kW?

The extra panels will be relatively cheap but more of their generation will be exported, which doesn’t help the economics.For example, depending on household consumption, a solar system rated at 5 kW might export 80% of its generation. Electricity exported to the grid only earns the feed-in tariff, ranging from 5 c to 14 c per kWh, depending on your location and electricity plan. Solar electricity used on-site, rather than exported, saves you paying the grid tariff, typically around 20 c to 35 c per kWh.

Surprisingly, our modelling of the economics found that a 5 kW system now has a shorter or equivalent payback time to the 2 kW system. We studied the economics by simulating a large number of scenarios in half-hour intervals for a whole year using Sunulator, ATA’s free solar feasibility calculator.

Our primary economic measure is payback time, the number of years until bill savings recoup the installation cost—the fewer years the better. Payback times shorter than 10 years are generally considered attractive to solar customers, as the system is likely to pay for itself before any significant expenses, such as replacing the inverter. The panels should last at least 20 years, so cumulative bill savings are large, especially for a larger system.

To do the modelling, we assumed a feed-in tariff of 11.3 c/kWh in Victoria and in other states a doubling of feed-in tariffs from current levels, phased in over the next five years. We considered common grid tariffs in each capital city, for a variety of household consumption profiles, along with likely tariff increases (we used AEMO’s retail tariff forecasts, but since they were based on Hazelwood closing in 2020, which happened this year, we pulled them forward by three years; this allows for annual tariff rises between 1.5% for Queensland and 3.4% for Tasmania). Panels are assumed to be north-facing with a 20-degree tilt. Our analysis also includes panel degradation over time.

Read the full article in ReNew 140The full report on solar sizing, including references, is available at www.ata.org.au/news/bigger-solar-is-better-ata-report

 

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.

EN_Datasheet_Honey_250-265-1

Product profile: Optimised solar panels

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Many solar arrays experience partial shading for part of the day—even a large bird dropping on a single solar panel can reduce that panel’s output considerably.

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Until recently the solution for optimising output has been to use either microinverters or solar optimisers on each panel—ie, optimisation at the panel level. Because solar panels have multiple separate strings of solar cells, optimising at the string level produces energy output improvements for panels experiencing shading on one of the strings, as the other two strings may be producing maximum output. With a panel-level optimised panel, the underperforming string will drag down the other two, but with a string-level optimised panel, the third string can be optimised for maximum total output.

Maxim Integrated has developed a small IC for string-level optimisation of solar panels. At least two manufacturers that supply the Australian market incorporate the Maxim optimisers into their panels—Jinko’s Smart Module and Trina’s Honey Maxim (pictured). These panels incorporate three optimiser ICs per panel, giving three separate strings that can be individually optimised.

RRP: POA. Jinko and Trina modules are available from numerous solar installers and are distributed by Krannich Solar (as well as some other distributors), www.krannich.com.au. Also see www.jinkosolar.com, www.trinasolar.com and www.maximintegrated.com

Read more product profiles in ReNew 140.

Longyangxia Dam Solar Park

Largest solar farm in the world

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Snapped by NASA satellite in January this year, the Longyangxia Dam Solar Park in China’s Qinghai province now lays claim to the title of ‘largest solar farm in the world’. Covering 27 square kilometres, the solar farm has 850MW of capacity and nearly 4 million solar panels, eclipsing the next largest in Tamil Nadu in India with a capacity of 648MW.

The NASA website describes the title of ‘largest solar farm in the world’ as “a rather short-lived distinction”: In 2014, the Topaz Solar Farm in California topped the list with its 550 MW capacity. They were edged out by Solar Star, also in California, at 579 MW in 2015. By 2016, India’s Kamuthi Solar Power Project in Tamil Nadu was on top with 648 MW of capacity.

As well as largest solar farm, in 2016 China got to claim the title of world’s largest producer of solar power. China’s total installed capacity doubled in 2016 to 77 GW, pushing them well ahead of Germany, Japan and the USA– though NASA notes those other countries produce more solar power per person.

The NASA post concludes: it’s unlikely that Longyangxia will remain the largest solar park in the world for long. A project under development in the Ningxia region in China’s northwest will have a capacity of 2000 MW when finished, according to Bloomberg.

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