In ‘Solar’ Category

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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.

More on this, click here

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“Heartening” doubling of Victorian feed-in tariff

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The ATA (ReNew’s publisher) has welcomed the Victorian Government move to more than double the minimum solar feed-in tariff . From 1 July 2017, the feed-in tariff for rooftop solar in Victoria will increase from 5 cents to 11.3 cents per kilowatt-hour, benefitting about 130,000 households. The change follows findings by the Essential Services Commission (ESC) in its report last year on the energy value of distributed generation.

“It’s very heartening for solar households in Victoria to have a government that is serious about renewable energy,” says Damien Moyse, the ATA’s policy and research manager. “We also congratulate the ESC for its work on the issue over the past 18 months.”

The ATA contends that solar households and businesses across Australia provide greater value into the national electricity market than the narrow methodology used to calculate feed-in tariffs up until now. The new feed-in tariff is closer to recognising the full value that distributed generation brings to our energy market, which is important as solar and other demand-side technologies continue to play a greater role in our energy mix.

We at both ReNew and the ATA would like to see other states following Victoria and accurately reflecting the value of distributed generation through their feed-in tariffs.

For analysis by Jack Gilding on the best range for feed-in tariffs, see here.

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.

Bringing nature back

Sub-tropical build – Bringing nature back

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Richard Proudfoot and his partner have brought nature in to their suburban block, at the same time as reducing energy and water use. He describes their house and garden build, and the satisfying birdsong-filled results.

IN 2008 we sold our small cottage in inner-city Balmain, in Sydney, and moved to Bribie Island, just off the Queensland coast between Brisbane and the Sunshine Coast.

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Why a life on Bribie Island? My partner Fiona was born and raised near Royal National Park, just south of Sydney. I was born and raised in the Australian outback. We both appreciate the bush and as we neared retirement, we looked for a simple, sustainable life in a leafy setting. While we loved the inner Sydney vibe, it could never be called simple, and true sustainability was always going to be difficult to achieve.

Bribie also has arguably Australia’s best climate. In summer, the temperature rarely exceeds 29 °C, while in winter the temperature range is 15 °C to 25 °C, and annual rainfall is 1.2 metres. It is a great environment to use passive solar design techniques to build a sustainable, more self-sufficient house.

We bought an ordinary suburban (650 m2) block (of sand!), 200 metres from the beach, bordered by neighbours on three sides. Much of the time, a cool sea breeze from the Coral Sea blows across our block. The block runs east-west and has many mature trees on the back boundary.

 

So what kind of house to build?

Working closely with the builder, we came up with a design based on their classic Queenslander kit home. The house is elevated to catch the sea breeze and there is always cool air flow under the floor. It has verandahs on all four sides. It has high ceilings with a fan in every room, essential for sub-tropical days and nights. Most of the windows are north facing. There is very little glazing on the south and west sides, to provide maximum protection from the many storms which come in from the south-west. Every room opens onto a verandah, including the bathroom.

We wondered about building on sand, but our builder allayed our concerns. He used about one metre (depth) of concrete per footing. He couldn’t go much deeper because the water table starts about two metres below the surface. To date we have not observed any cracks in the walls, so our initial concerns appear to have been unwarranted.

Read the full article in ReNew 139.

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100% renewables – how feasible is it?

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With ongoing discussion by government and media about the effect of renewables on the grid, the ATA’s Andrew Reddaway and Damien Moyse consider the feasibility of 100% renewables for Australia.

THE ATA (ReNew’s publisher) supports a transition from fossil fuels to renewable generation in Australia’s electricity grid.
As well as being important to meet our international commitments to fight climate change, this brings other benefits such as improved local health outcomes, greater energy security and more jobs.

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However, as this transition progresses we must ensure the grid remains reliable and avoid economic hardship. How can this be achieved as we approach 100% renewables? This article considers the challenges of relying on intermittent generation, ways to address those challenges and a plan for moving forward.

Read the full article in this month’s longform.

Read more articles in ReNew 138.

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Island of energy: community-owned and renewable

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Denmark’s Samso Island went from complete reliance on imported oil and coal to 100% renewable electricity in just a decade. Jayitri Smiles and Nicky Ison explore the community and government partnerships that made it happen.

DURING the global oil crisis in 1973, Denmark began to think creatively about how to supply cheap energy to their population. As they built their first wind turbine, they were unknowingly establishing themselves as future world leaders in renewable energy.

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Today, Denmark aims to have renewable energy powering 100% of their country by 2050 and to eliminate coal usage by 2030. These targets build on a track record of success: since the 1990s Denmark has witnessed the quadrupling of renewable energy consumption.

The creation of the world’s first fully renewable energy powered island, Samso, is an exemplar of Denmark’s leadership. Not only has Samso become a carbon-negative region, but it has accomplished this world-first using community investment.

In 1997, Denmark’s Minister for Environment Svend Auken was inspired at the Kyoto climate talks. He returned home with a passion to harness the collective efforts of local Danish communities in a way that promoted self-sufficiency in renewable energy. Auken held a competition, which encouraged Danish islands to consider how their clean energy potential could be achieved with government funding and matching local investment.

The most compelling application came from Samso, a small island west of Copenhagen with a population of 4100. This island of 22 villages, at the time run purely on imported oil and coal, was suddenly thrust into the global spotlight and, through a combination of local tenacity, investment and government funding, transitioned to 100% renewable power in just a decade.

At the heart of this energy revolution sit Samso’s community-owned wind turbines. Onshore turbines with a generation capacity of 11 MW offset 100% of the island’s electricity consumption. Another 23 MW of generation capacity from ten offshore turbines offsets Samso’s transport emissions. Most (75%) of the houses on the island use straw-burning boilers via district heating systems to heat water and homes, and the remainder use heat pumps and solar hot water systems.

The extraordinary result is a carbon-negative island and community. The island now has a carbon footprint of negative 12 tonnes per person per year, a reduction of 140% since the 1990s (compare this to Australia’s footprint of 16.3 tonnes per person in 2013 and Denmark’s overall footprint of 6.8). Not only is the island energy self-sufficient, they now export renewable energy to other regions of Denmark, which provides US $8 million in annual revenue to local investors.

And Samso is not slowing down. Highly motivated, knowledgeable and passionate locals are aiming for the island to be completely fossil-fuel free by 2030. They plan to convert their ferry to biogas and, despite already offsetting their vehicle emissions via renewable energy generation, residents of Samso now own the highest number of electric cars per capita in Denmark.

 

Read about their transition in ReNew 138.

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Islands in the sun (and wind)

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The idea of moving to renewable energy generation is proving attractive to many smaller communities, particularly island-based communities. Here are some of them.

Kangaroo Island: Currently powered by a 15 km undersea cable from mainland SA which is nearing the end of its design life, one option, moving the island to renewable energy generation, has been examined by UTS Institute For Sustainable Futures. The outcome of the study was that the cost of replacing the undersea cable would come in at $77 m whereas a local wind/solar/diesel hybrid system was estimated at around $87 m. However, once ongoing costs such as network charges are factored in, costs for the new cable option rise to $169 m, compared to $159 m for local supply. The system would likely include doubling the existing 8 MW diesel generation capacity, installing between four and eight wind turbines, adding five hectares of solar farm and around 800 solar rooftops. The end result would be 86% renewable and 14% diesel generation.
www.bit.ly/KangUTS100

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Isle of Eigg, Scotland: In 2008, the island’s electrification project was switched on, providing 24-hour power for the entire island. Previously, electricity had been provided by individual households using their own generators, resulting in excessive noise, pollution and high maintenance burdens on individuals. The project included laying of 11 km of cable and installation of three hydroelectric generators—100 kW at Laig on the west side of the island, with two smaller 5 to 6 kW hydros on the east side. Four small 6 kW wind turbines below An Sgurr and a 50 kW photovoltaic array round out the system. There are also backup generators for periods of low renewable input. To prevent overloading of the grid, each house has a maximum power draw of 5 kW, and 10 kW for businesses. When excess renewable energy is being generated, the electricity is used to heat community buildings.
www.islandsgoinggreen.org

Bruny Island, Tasmania: As looked at in ReNew 136, the CONSORT Bruny Island Battery Trial is an ARENA-funded project to install up to 40 battery systems on the island, with the view to stabilising the grid and reducing the use of diesel generation during the peak season. Households that participate in the trial will be provided with a large subsidy to install solar power and a smart battery storage system. They will also be able to sell their stored energy into the electricity market via Reposit Power. So far, the first round of participants have been selected. www.brunybatterytrial.org

Rottnest Island: The Rottnest Island Water and Renewable Energy Nexus project involves the construction of a 600 kW solar farm to complement the existing 600 kW wind turbine, which was installed in 2005 and already produces around 30% of the island’s electricity needs, saving more than 300,000 litres of diesel a year. The solar farm is expected to push the renewables portion to 45%, further reducing the need for diesel fuel. Funding for the project will be jointly provided by the Rottnest Island Authority ($2 m) and ARENA, which will provide $4 m. www.bit.ly/RottnestSust

King Island: The King Island Renewable Energy Integration Project (KIREIP) aims to increase the island’s renewable energy generation to around 65%, and up to 100% at times, while reducing the reliance on diesel fuel. By adding energy storage and energy flow control, the system allows greater contribution of power from renewable sources. Integration of smart grid technology provides the ability to control customer demand to match the available renewable energy supplies. The storage system, the largest electrochemical battery ever installed in Australia, is capable of producing 3 MW of power and storing 1.6 MWh of usable energy.
www.kingislandrenewableenergy.com.au

Island of Ta’u: The island of Ta’u in American Samoa lies around 6400 km off the west coast of the USA. Until recently it was entirely diesel-powered, with diesel being delivered by ship. Disruptions to deliveries had at times resulted in severe electricity restrictions—not great when you rely on electric pumps for basic water requirements. Ta’u now has a solar power and battery microgrid that can supply nearly 100% of the island’s electricity requirements from renewable energy. The new microgrid has all but eliminated power outages and greatly reduced the cost of providing electricity to Ta’u’s almost 600 residents. The system consists of a healthy 1.4 MW of solar generation capacity from SolarCity, which feeds into 6 MWh of grid-grade storage from Tesla (Tesla recently aquired SolarCity) consisting of 60 Tesla Powerpacks. The project was funded by the American Samoa Economic Development Authority, the US Environmental Protection Agency, and the US Department of Interior. It is expected to offset more than 400,000 litres of diesel per year.
blog.solarcity.com/island-in-the-sun

Read more in ReNew 138.

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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.

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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.