In ‘Solar’ Category

Chris's off-grid wind and solar system powers his home and electric vehicle.

Off-grid wind and solar

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It’s a windy place near Canberra, and Chris Kelman is taking good advantage of that! He describes the evolution of his impressive off-grid wind and solar system — and the avid meter-watching that goes with it.

In a quest to demonstrate the possibility of living a fossil-fuel-free life, I have now made a couple of attempts at setting up my house to run on ‘home-grown’ energy.

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My first project, back in 1987, used home-made solar hot water panels, a ‘massive’ 90 watts of PV plus a 1 kW Dunlite wind generator (pictured on the cover of Soft Technology 32–33, October 1989; Soft Technology was the original name of ReNew). At this stage, renewable energy technology was in its infancy and everything was DIY, including building an 18 m tripod tower for the turbine (overcoming a fear of heights was a personal fringe benefit). On this basic system I did manage to run lights, computer, TV and stereo, but there were thin times, of course.

These days, home energy systems are more like Lego — you just plug and play. So with a move back to the bush near Canberra a few years ago, I decided to do it all again, but this time with sufficient capacity to run a standard 230 V AC all-electric house, workshop, water pumps—and an electric vehicle.
The house I purchased had been set up pretty well as a passive-solar home, though it was connected to the grid at the time. It has a north-facing aspect, good insulation and a lot of (double-glazed) windows allowing winter sun to maintain a cosy slate floor. The result is a very stable environment for most of the year.

Energy production—phase 1
In phase one of my new project,in 2012, I installed 3 kW of PV with a Sunny Island off-grid inverter and 40 kWh of VRLA (valve-regulated lead-acid) batteries. Initially, hedging my bets, I configured it as a grid-connected system, with the grid acting as a backup ‘generator’ when required.

After a few months I realised that I rarely needed to use the grid and, as I owned a small antiquated petrol generator from my previous project, I decided it was time to cut the umbilical cord. This turned out to be a rather amusing process. My local energy provider didn’t seem to have an appropriate form for ‘removal of service’ and was bemused about why I would ask them to take the meters away. It was all a bit much for them. Even after the process was completed, I would still occasionally discover lost-looking meter readers around the back of the house!

The weather in this region is well known for its reliable solar insolation, apart from some lean months in mid-winter. Fortunately we are well supplied with wind power as well, as indicated by the Capital wind farm only a few kilometres away.

To confirm the wind resource, I set up a Davis weather station on a 12 m mast at my proposed turbine site and undertook a six-month wind survey. The results from this were compared with historical records from the area and a good correlation was found. This was enough evidence to convince me that wind power backup, particularly to cover the lean winter months, was the best option for my system.

Read the full article about Chris’s impressive off-grid setup in ReNew 134.

”The future is bright fellow women of renewable energy.” Miwa Tominaga delivering a rousing speech at the
2015 All Energy Conference. Photo courtesy of the Clean Energy Council.

The double-glazed ceiling: Women in renewables

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When asked why it is important to have a gender balanced cabinet, Canada’s Prime Minister replied, “Because it’s 2015.” Sarah Coles looks around in 2015, wonders why Australian women are under-represented in the renewables sector and speaks with leaders in the field about ways to address the imbalance.

LAST month the Clean Energy Council (CEC), the peak body for renewables in Australia, held a Women in Renewables lunch as part of the All-Energy Conference in Melbourne. The lunch was organised by Alicia Webb, Policy Manager at the CEC. Roughly 20,000 people work in the renewables sector in Australia. Men outnumber women in all fields: solar, wind engineering, energy efficiency, hydro, bioenergy, energy storage, geothermal and marine. At the 2015 Australian Clean Energy Summit hosted by the CEC there were 93 speakers, 11 of whom were women.

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Women are generally under-represented across science, technology, engineering and mathematics (STEM) fields. According to the Australian Bureau of Statistics, of the 2.7 million people with higher level STEM qualifications in 2010–11, men accounted for around 81%.

There are myriad reasons for the low numbers of women in renewables. Gender disparity starts early with cultural stereotypes and lack of encouragement from teachers. Around 25% of girls are not doing any maths subjects in their last years at high school. When I was in year ten and acing science, my biology teacher said to my mother, “Sarah is good now but her grades will suffer when she starts noticing boys.” Returning home my mother (holder of a science degree) delivered a succinct verdict, ”Mr P. can get stuffed.” But discrimination like this is still common.

Some people think a change in governance is needed; that if there are more women in leadership roles this will have a trickle-down effect. As of 2014, women made up 21% of the Rio Tinto board and 22% of Qantas. Stats like these are often bandied about as examples of progress but to my mind if you take a big piece of pie and cut it in half you end up with two equal portions, not one piddley 22% sized piece and one 78% chunk. I decided to speak with some women at the top of their game to find out what should be done to even up the portions.

Miwa Tominaga

Miwa Tominaga knows what it is like to face gender discrimination at work. Miwa’s first full-time job was as the only female electronics technician at a radio transmitter site. She moved to Victoria to pursue a career in the sector, first working as a CAD drafter for electrical building services and then landing a job in renewables doing technical support at a company that manufactures electronic solar charge controllers. While she was working she studied renewable energy through an online course. When she provided phone support, hearing a woman, people would often ask to be put through to someone technical.

Later, installing solar panels at Going Solar, a woman said to Miwa, “Don’t take this the wrong way, but you do know what you are doing, don’t you?” The answer is a resounding yes. Miwa won 2014 CEC’s awards for ‘best install under 15kW’ and ‘best stand-alone system’. She currently works at a solar inverter manufacturer doing sales and tech support: “because it’s a worldwide company there are lots of opportunities.”

When I ask Miwa about discrimination she says, “A lot of women have experienced renewables being a male-dominated industry.” Miwa gave a speech about it at the CEC lunch. “I think it makes a huge difference if you’re working with men that see you as an equal not as an assistant. There have definitely been times when I have been judged for being a woman, especially by customers.” But she says that most of the time people are very supportive or indifferent towards her gender. “They say, ‘Oh wow, you’re gonna get on the roof by yourself!’”

Miwa thinks a top-down approach is a game changer. Danish legislation requires companies to work actively towards gender equality. It is one of the countries that has legislated for quotas around female board representation. Norway passed a law in 2005 requiring companies to appoint boards that include at least 40% women. Malaysia passed a law requiring female board representation of at least 30% by 2016. Miwa thinks Australia needs quotas too. “Start from the top at the board level. I do some volunteering for Beyond Zero Emissions (BZE) and I know that they make sure the board is about 50% women, 50% men. It makes a difference when they start at the top. It sets an example and really gives women opportunity.”

Emma Lucia

Emma Lucia felt empowered by encouraging teachers at school, and went on to study Mechanical Engineering and Arts at Monash University. Emma says she became interested in renewables when she was at university and studied abroad. “When I was finishing university everyone went into either automotive, mining, or oil and gas. My first job was actually supposed to be as a mining consulting engineer! I remember sitting in an environmental engineering class, which I did as an elective in my final year of university and thinking, ‘Is this [mining] what I really want to do with my life?’ I wanted to have a positive influence on the environment not a negative one.” The mining consultant role fell through and Emma worked as a building services engineer doing environmentally sustainable designs. “Through that I knew energy is where I wanted to be. I wanted to be in renewable energy. I could see that that would be a game changer.”

Early on in her career she felt constrained by the attitudes in the male-dominated engineering field. “In one company the more interesting work was often offered to my male colleague ahead of me,” says Emma. She found support, though, from other colleagues, who refused to see her sidelined. But it was difficult having to fight such battles, and in the end she decided a sideways transition was needed. “I now work in a more people- oriented role, but still using my skills, and in a renewable energy company. It’s been a good move,” says Emma.

She believes that having support mechanisms within organisations is a crucial step in overcoming discrimination. Emma says that “sometimes women may be a little bit more self doubting” so support from the organisation can help. “Also you need to trust yourself and trust in your abilities and really back yourself.” She adds, “Find a mentor or trusted advisor or someone you can bounce ideas off of who can help you cut through when you have problems in your career.” Emma thinks a key to gender diversity is to network with like-minded women and to get more women on boards, “I’m on the board of the Australian Institute of Energy and I actively look to increase the diversity of our committee members and speakers. I feel very strongly that change doesn’t happen in isolation.”

Katrina Swalwell

Dr Katrina Swalwell is a senior wind engineer and former Secretary of the Australasian Wind Engineering Society. After school, Katrina was all set to go into science at university but happened to do work experience at CSIRO with an engineer who said, “Why don’t you go and become an engineer and get paid more for doing the same job?” She completed a Science and Mechanical Engineering degree followed by six months study in Denmark looking at wind turbines. At university, about 20% of the undergraduates in engineering were women. “The vast majority of my fellow students were really supportive, nice guys. I had one case where a guy complained openly that I got better marks than him because I was a female. My friends and I just laughed because I did preparations for the pracs and he never did, so we thought that might have a bit more to do with it.”

Katrina says that, while she has always been supported in her career, most of her female friends who went through in engineering are no longer working in technical roles: ”The opportunities aren’t necessarily there. There are more opportunities in management or other things. They’ve gone into a whole variety of roles, a lot of them technically related, like one is a patent lawyer and one does electricity market modelling; she would call herself a modeller rather than an engineer now.” It isn’t all doom and gloom: “I think renewables is a great industry in that it is relatively new so there isn’t that entrenched resistance to females in the roles.”

Katrina says flexibility is key to attracting more women to male-dominated roles. For example, in Denmark there is state-supplied childcare. “The company that I work for is German. They’ve got laws now where there is six months paternity leave just for the father, so it has really prompted guys to take some time out.” Taking time off becomes more accepted for everybody as a result.

Katrina says girls need to be informed about their options, “If I hadn’t had that mentor when I was in year 12, I probably wouldn’t have been an engineer.” Like Miwa and Emma, Katrina sees boards as an important catalyst for change. “I’ve been involved in the women on boards group. They encourage women to consider taking board roles. They provide a service for companies that are looking to increase their gender diversity.”

Mentoring, support for diversity, workplace policies that support flexible working hours, baseline measurements and representation targets are some of the ideas for tackling the under-representation of women in renewables. At last year’s All-Energy Conference there were only three women speakers out of a total of 30. We still have a long way to go but change is afoot. The Clean Energy Council has introduced a policy of no all-male panels at the 2016 conference.

The renewables industry in Australia is working hard to accelerate the advancement of women but it needs to get gender equality targets enshrined in law. We need to address gender pay gaps, prioritise the issue and create accountability. We often hear politicians speaking about renewables targets but the time is ripe for them to address the issue of gender targets across this booming sector because, as Emma puts it, “Renewables are going to play a significant role in Australia’s growth so encouraging diversity in renewables will ensure better outcomes for the future of our country.”

Lego v Barbie

Miwa: “I was definitely a Lego kid. I ended up playing with a lot of my brother’s cars and stuff. I think my Mum stopped buying me Barbies because I didn’t play with them!”

Emma: “I did have a Lego kit and another one of my favourite toys was my Barbie Ferrari car.”

Katrina: “I had a Lego technical kit, the one with motors, so I could play with that. I was encouraged to explore whatever I wanted to do but I think my mother was still very surprised when I chose to do engineering

Image: ”The future is bright fellow women of renewable energy.” Miwa Tominaga delivering a rousing speech at the
2015 All Energy Conference. Photo courtesy of the Clean Energy Council.

 

Solar_Reserve_project

The future of energy: Large-scale solar worldwide

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Not just good for the planet, large-scale solar is now often the cheapest option. Lance Turner looks at some of the impressive projects powering up right now.

As the world’s governments slowly wake up to the reality of climate change and the need to shift energy generation away from fossil fuels to renewables, the corporate world is just getting on and doing it.

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Large-scale wind farms have become common, but large-scale solar farms are less so. However, this seems to be changing, with multi-megawatt and even gigawatt-scale solar generation plants being developed at a considerable pace.

Cheaper than the fossils
The main driver behind this seems to be that solar has actually become one of the cheapest forms of energy generation. In many cases, solar plants are proving to be cheaper than gas, nuclear and even coal-fired power plants, especially when the complete life cycle and environmental factors are taken into account. Indeed, recent tenders in both Chile and India for energy generation have been won by solar because it was the cheapest option. The Chilean auction was open to all technologies, yet solar won the majority of the generation contracts, with other renewables taking the rest. Not a single megawatt of generation capacity went to fossil fuel projects. Further, the auction produced the lowest ever price for unsubsidised solar at just US 6.5 c/kWh!

The huge US renewable energy development company SunEdison won the entire 500 MW of solar capacity on auction in the Indian state of Andhra Pradesh with a record low unsubsidised tariff for India of 4.63 rupee/kWh (US 7.1 c/kWh)—lower than new coal generation, particularly when using imported coal.

It’s not just in the developing world that solar is beating fossil fuels. In October, an auction in Austin, Texas, resulted in 300 MW of large-scale solar PV being contracted at less than US 4 c/kWh. Even before tax credits, the price is still under US 6 c/kWh—beating gas and new coal plants.

While many of these contracts involved photovoltaics, other forms of solar generation such as concentrated solar thermal systems also fared well, gaining some contracts and producing prices under US 10 c/kWh.

Read the full article in ReNew 134.

PV panels - pvcycle

A recycling round-up

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Lance Turner considers the evolving recycling options for some of the common technologies in households: solar panels, lights and batteries.

Solar panel recycling
Up until recently there have been no official schemes for recycling solar panels in Australia. However, as the number of broken and otherwise failed panels begins to grow, so has the need for recycling.

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But how much solar panel waste is there at present, and what are we looking at down the track when the current explosion of solar panel installations come to the end of their working life?
Although figures are hard to come by, one typical example is that of Japan, which has seen considerable growth in PV installations in recent years. According to the Japanese Ministry of the Environment, by 2040 770,000 tonnes of solar panels will need to be recycled. The ministry has stated that, in conjunction with the Ministry of Economy, Trade and Industry (METI) and industry organisations, it will begin to implement measures for “removal, transportation and processing of solar power generation equipment” before the end of this fiscal year, in March 2016 (from www.bit.ly/1PwRFfC).

In Europe, requirements have already been added to the Waste Electrical and Electronic Equipment (WEEE) directive, bringing in a take-back and recycling scheme to deal with solar panel waste. The program, PV Cycle (www.pvcycle.org), provides fixed collection points, collection services for large quantities, and collection via distributors.

The WEEE directive means that solar panel manufacturers not only have to ensure collection and recycling of their products when they have reached their end of life, they will also be required to ensure the financial future of PV waste management.

Looking at Australia, there is currently (as of March 2015) 4.1 GW of installed capacity of solar PV. Assuming around 250 watts per panel (a common size), that’s around 16 million solar panels. With an approximate weight of 18 kg per panel, you are looking at 288,000 tonnes of solar panels, or around 11,500 tonnes per year (assuming a lifespan of 25 years) needing to be recycled. Of course, many PV panels will have a greater lifespan, while other, lesser quality panels will die sooner, so these figures are really just ballpark.

Regardless, that’s a great deal of materials needing to be recycled, most of which is glass, silicon cells (a glass-like material) and aluminium.
Aluminium framing is easily recycled in existing aluminium smelters. However, without a system of collection, transportation and dismantling of solar panels, these materials are currently going to waste, usually ending up in landfill.

Read the full article in ReNew 133.

Three options of hot water plumbing: gas-boosted solar, full gas and solar only.

Farming Renewably: Reaping the benefits

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One person/farm can make a difference: David Hamilton describes how his farm’s sustainable conversion cut carbon, benefited the landscape and turned a profit.

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I’ve read many inspiring articles in ReNew from individuals trying to live more sustainably and lessen their impact on the planet. This article takes a slightly different approach–a rural perspective–to demonstrate that it can be commercially viable to run a farming enterprise using systems that are truly renewable, whether that’s for water, electricity, housing, food, livestock, pasture or wildlife.

Our journey to sustainable farming began in 1993, when my wife Roberta and I purchased a 60-acre property in the south-west of WA with the twin objectives of restoring the degraded land and becoming as self-reliant as possible. The land included pasture that was totally lifeless and neglected, along with a dam, two winter streams, old gravel pits and two areas of magnificent remnant native forest. We wanted to be independent for water, electricity and as much of our food as was practical. Withe fewer bills to pay, we could work fewer hours off the farm–which was very appealing.

As a registered nurse with no farming experience, I was on a vertical learnign curve. Luckily, Roberta has a dairy farming background and, with her accounting experience, is a wizard at making a dollar go a long way.

When we began, we were both working full-time. We spent the first two years establishing a gravity-fed water supply, preparing the hosue and shed sites, and fencing the property, including to protect remnant bush from planned livestock. We also planted over a thousand native trees and shrubs, plus a few ‘feral’ trees for their air conditioning and fire-retardant properties.

Read the full article in ReNew 132.

 

Bosch_hybrid

Going hybrid: Adding batteries to grid-connected solar

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Going off-grid may not be for everyone; a better route may be to ‘go hybrid’, by adding batteries to grid-connected solar. Andrew Reddaway explores the options.

The solar battery industry is on the verge of disruptive change. Traditionally, large batteries were only seen in houses at off-grid locations such as Moora Moora (see box on the solar hybrid training course held there, which I attended earlier this year and which provided input to this article).

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For off-grid systems, reliability is crucial; failure prompts an emergency call to the solar installer, so such systems have been designed conservatively using proven lead-acid batteries.

Meanwhile, in towns and cities, grid-connected solar systems have gone mainstream. As feed-in tariffs for solar export have dropped far below the rates paid for grid electricity, householders are looking for ways to cut bills by making better use of their excess solar generation. One answer is to add batteries to create a hybrid system: a grid-connected solar system with batteries either for backup or load-shifting.

This article gives an overview of current hybrid technology and the options available for adding batteries to an existing grid-connected solar system.

Different batteries for hybrid
A hybrid solar system is tough on batteries. Unlike an off-grid system that may store enough energy to last multiple days, a hybrid system’s entire usable capacity will be charged and discharged daily. This requires a battery that can handle fast discharge rates at high levels of efficiency. Lithium batteries fit the bill, and have already become dominant in consumer electronics, power tools and electric cars. Compared to lead-acid, they are also smaller, lighter, don’t require monthly maintenance and don’t emit hydrogen gas. The only things holding them back in the solar market are unfamiliarity and price.

The recently announced lithium Powerwall battery from Tesla is priced well below previous products and has a 10-year warranty. Traditional lead-acid batteries cannot compete with this new benchmark, so it’s expected that systems will start to move away from them. Hybrid systems are now expected to become viable on pure economics in a few years or less. Early adopters are already installing lithium hybrid systems, as are some who value maintaining power during a blackout.

Read the full article in ReNew 132.

132_solar_heating

Low cost solar heating: Using free heat from your roof

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After reading an article in ReNew, Alan Cotterill decided to design a closed loop heat exchange system to supplement his home’s heating with free heat from the roof. A couple of iterations later, he describes the resulting effective system.

In early 2014 I commenced efforts to use the heat from our roof cavity to contribute to winter heating. I decided on a closed loop system, which would take in room air, duct it through the roof and return it to the house at a higher temperature. A closed loop system avoids the issue of drawing down insulation fibres and dust from the roof cavity.

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Useful attic temperatures
My home combined with our very cold but sunny winter days in Wagga seemed especially suitable for this system to run with reasonable efficiency. The house has a grey Colorbond steel roof and a large roof area relative to the internal floorplan, due to a high pitched roof and the wide verandahs and garage being included under the main roof structure. The east-west orientation of the long axis of the house and the north-facing roof area being covered with solar panels have not prevented useful attic temperatures. Measured 60 cm below the peak of the roof cavity, the average maximum attic temperature was 28 °C for the two weeks starting 16 July 2014 and 37.8 °C for the two weeks from 19 August 2014.

A first attempt
My first prototype forced room air through a system of ducts in the roof using a centrifugal exhaust fan mounted on its side on a shelf in the laundry. The air was distributed to three 12-metre runs of 100 mm flexible aluminium ducting before returning the air to the house. The returned air was reasonably heated but the total volume of returned air was inadequate to contribute significantly to winter heating.

Read the full article in ReNew 132.

Montessori-solar1_small

Revolving donations fund 35kW of community solar

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A people-powered movement is helping to fast track Australia’s renewable energy revolution. 

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A recent solar PV installation at Camden Park, SA brings the total amount installed by CORENA’s Quick Win community solar projects so far to 35kW. Another 8kW has been added by recipient organisations in conjunction with these projects, giving an overall result of 43kW installed. Two of the projects have also included replacing lights with LED alternatives.

CORENA (Citizens Own Renewable Energy Network Australia Incorporated) provides interest-free loans to pay for solar installations and energy efficiency measures. The loans are repaid over about five years out of the resultant savings on power bills, meaning that non-profit organisations can reduce their carbon emissions without diverting funds from their core purpose. As the projects ‘pay for themselves’, the original donations are then used over and over again in new projects.

CORENA has now funded Quick Win projects for four non-profit organisations in three states: Tulgeen Disability Services in Bega (NSW), Gawler Community House (SA), Beechworth Montessori School (Vic), and Camden Community Centre (SA). The next project in line, in Nannup (WA), is already half-funded, and a community centre in Ravenshoe (Qld) is queued as Project 6.

“After just four projects the growth potential of our revolving funding model is looking quite exciting,” said CORENA spokesperson Margaret Hender. “The four projects completed so far have cost a total of $63,460. Climate-concerned citizens donated most of that, but $10,438 of it came from loan repayments from completed projects.

“The first project was funded entirely from donations, but already $5,000 of that loan has been paid back into the revolving pool of funds,” said Ms Hender. “As the number of completed projects increases, an increasing proportion of the cost of new projects is covered by loan repayments. Eventually the revolving loan repayments will cover 90%, or even 100%, of the cost of new projects.

“I could talk to politicians until I’m blue in the face in the hope of getting better renewable energy policies, and never know if I’ve had any effect,” said Ms Hender. “But if I put $100, or $10 a week, for example, into solar panels on a roof somewhere, within a matter of weeks my money will be reducing carbon emissions and keep on doing so forever as it is used again and again in future projects.”

For more information visit www.corenafund.org.au

 

 

ev delaware

Not just transport: Your EV’s other life

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Electric vehicle by day, powering your home by night? Kristian Handberg explains how EVs could help in the energy storage equation.

For those with solar PV systems getting paid next to nothing for their surplus generation, the day is fast approaching when they might store this energy for later use. But should they use a stationary battery or an electric vehicle?

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The situation for stationary batteries is changing rapidly. Battery costs are coming down and electricity market rules are changing to accommodate new business models for energy sellers who use storage1. Solar homeowners may soon be offered energy supply agreements that include a battery located on their property but owned and operated by their electricity retailer2. Homeowners will see the benefits via reduced electricity costs and supply agreements that avoid the complexity and risk of owning and operating a grid-connected energy storage system.

Right now, however, solar homeowners must deal with these challenges themselves. High upfront costs and long paybacks, risks associated with new technology and warranty commitments, and complicated energy management strategies are all reasons to delay on battery investment or look for alternatives.

One of these alternatives may be to use an electric vehicle as storage—if an electric car works for your transport needs, why not also use it to get better value from your solar investment.

While vehicle charging can be managed in line with solar production, at present there are no electric cars in the Australian market that allow charge to be extracted for other uses. Equipment is sold in Japan that allows emergency backup power to be obtained directly from the vehicle (see box on this page), along with vehicle-to-home (V2H) charging solutions that can provide backup and solar PV optimisation. Combining a standard charger with a bi-directional inverter (supporting both the vehicle charging and discharging) and an energy management controller, these V2H systems currently cost around $1000/kW (or around $4000 for a 16A V2H unit, as compared to $500–$1000 for a standard 16 A charger).

These costs can be expected to decrease as the technology improves and the plug-in vehicle market grows. Driven by these changes and the results of trials currently underway, the analysts Navigant are forecasting that V2X-enabled vehicles (vehicles which support discharging activities) will be launched internationally in 2016 alongside improved V2H systems3.

As the technology evolves, there will be opportunities for householders, within the context of wider considerations.

Read the full article in ReNew 131.

solar finance

Solar financing

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Andrew Reddaway considers whether there are savings to be found in financing your solar install.

“Save money from day one”—sounds pretty good doesn’t it? Several companies offer to finance your solar install, claiming that savings on your electricity bill will outweigh repayments so you will be better off. But how far ahead might you be?

Solar financing options

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For this article we looked at several options to pay for a solar system:

  • pay upfront
  • redraw from your mortgage
  • unsecured finance
  • Environmental Upgrade Agreement (EUA)
  • Power Purchasing Agreement (PPA).

Pay upfront

This option is only available if you have sufficient savings to draw on. The only finance-related cost is the ‘opportunity cost’: if you hadn’t spent the money on a solar system, you could have invested it instead and made a return. For example, you could have invested in a term deposit earning 3.7% per annum (before tax).

Redraw from mortgage

Home loans are secured by your house so the interest rate is low e.g. 6% per annum.

Unsecured finance

Many solar installers will offer finance, typically from an external funder. Separate finance is also available from financial institutions. If the loan is set up as a lease, the lender may be responsible for maintenance. Repayment amounts, durations and fees vary considerably, but the deals we’ve seen have effective annual interest rates ranging from 10% to 28%. Watch out for apparently cheap finance attached to an inflated system price, or direct debit fees that continue after you’ve repaid the loan.

Environmental upgrade agreement

Currently EUAs are offered by a few councils through targeted programs. The council lends you money (from an external finance organisation) and you pay it back via a special charge on your council rates. If you move out, the repayments are taken up by the new owner. This allows for cheap finance with long repayment periods.

Power purchasing agreement

Under a PPA you do not own the solar system. Instead its generation is metered and the solar installer bills you; for example, they might bill you 21c per kWh. You still get a bill from your grid energy retailer, but the total of the two bills should be less than your previous bill. There are several variations of PPA so watch out for issues such as moving house or roof damage. Also, what happens when you’re not home and the solar system is exporting to the grid? If you still have to pay the installer, then the solar system may actually be costing you money at those times.

Read the full article in ReNew 131.

 

Reticulation_System

Building a solar reticulation system

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Martin Chape explains how he replaced a power-hungry bore pump with a low-cost solar unit and automated his watering system at the same time.

For some time I’d wanted to get rid of my power-hungry three-phase mains-operated bore pump, used to water my garden from the aquifer beneath my house. This forms part of a bigger plan to move all my 240 volt appliances off-grid. The large power drain of the three-phase bore pump would almost double the size of the inverter I’d need to go off-grid, even though it only gets used in summer, and then for just 15 minutes, three times a week.

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So, I decided to replace it with a 24 volt DC bore pump run from solar PV. This pump fills a rainwater tank from the bore, using a float switch to turn the pump off when the tank is full. The resulting system can be completely automated and independent of utility-supplied water and electricity.

The pumps and tank

I ordered a 24 volt DC multistage submersible bore pump (a Kerry M243T-20) from a dealer on AliExpress, for US $178. This pump is class IP68 (fully dust and water tight; see en.wikipedia.org/wiki/IP_Code), has a 25 mm outlet pipe, can pump to a head of 20 metres at 3000 litres per hour and draws 384 watts (at 24 volts that’s about 16 amps).

While waiting for the solar pump to arrive I removed the existing bore pump and sold it for $500. Using that as my starting capital, I hunted down a 2500 litre poly rainwater tank through Gumtree and, with the help of my neighbour, installed it on a brick and concrete foundation. I had first considered building an elevated tank stand, to provide water pressure from the height, but decided against this after reading a story of a home-built stand collapsing on someone. I also would have needed local government approval.

So the tank ended up on the ground and I purchased a second pump to move the water out of the tank to the garden. It’s a 24 volt DC submersible pump (US$35 from another AliExpress seller) with a single impeller (the spinning rotor that pushes the water), a 25 mm outlet pipe, 12 metre head capacity and it draws 120 watts. Oddly, it claims a flow rate of 8000 litres per hour compared to the 3000 litres of the bore pump.

[Ed note: Cheap devices bought directly from China can vary in quality; checking the seller’s feedback score and comments can assist, but as Martin’s experiences show, there can still be issues.]
When this pump arrived from China it had been damaged in transit so I ordered a second one and then contacted the supplier. The supplier was very good and supplied parts which I used to repair the first pump, which is now in my shed as a spare.

The solar bore pump then arrived and with the help of a friend I soon had it installed in the bore. It seemed to work initially, but then stopped after just 10 minutes.
I contacted the supplier in China but they claimed their pumps don’t fail. After many tests and emails, I removed the pump from the bore and made a video of it running in a container of water. The video clearly showed that it didn’t pump water but rather blew out smoke. Only then did the manufacturer agree to replace the pump—if I paid the shipping from China for the new one.

When the replacement bore pump arrived, I installed it in the bore and wired it through the float switch (a boat bilge switch) mounted upside down in the top of the rainwater tank. This switch turns the pump off when the tank is full.

Read the full article in ReNew 131.

14-11-30 3 Batt charger inverter

Going off-grid slowly: a DIY project

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Stan Baker dreams of ditching his energy company and going off-grid. He explains how he aims to achieve this, one step at a time.

The well-documented ‘gold plating’ of the poles and wires networks has meant rising service fees for consumers despite falling demand for delivered energy. My own electricity bills reflected this and caused me to seriously consider leaving the grid altogether. A further consideration was the increasingly disruptive weather being experienced around the country resulting in power outages caused by high winds and electrical storms. When attempting to be energy independent, however, the problem is the high cost of the batteries and other equipment necessary to generate and deliver electricity.

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Being something of a DIY type, I considered what bits I had sitting around in my garage and what expertise I might have that could be relevant. A passion over the years for converting hybrid cars to plug-in hybrids meant I had a reasonable understanding of lithium batteries, including the management electronics needed to ensure their longevity. I also had a 1.5 kW, 12 VDC Latronics inverter acquired years earlier for some long-forgotten project. Naturally, I had the usual nerdy stuff such as miscellaneous electronic parts as well as some understanding of microcontrollers.

In effect, I had much of what was needed to deliver 240 VAC off-grid, but with one question unanswered: where was the input energy to come from?

First attempts

My house has a flexible pricing plan from Origin that provides cheaper electricity between 11 pm and 7am. This meant I had a lower cost source of electricity for charging the batteries, at least for initial trialling. So, about six months ago I put together a simple system using lithium iron phosphate (LiFePO4) batteries from an electric vehicle conversion that were down to around 50% of their original capacity and therefore unsuited for vehicular use.

The battery charger was a simple linear unit that used toroidal transformers. I had my fuse box modified so that the lights in the house could be powered either from the inverter or directly from the mains.

The original system was not particularly efficient and I estimated I was losing around 50% of the incoming energy, mainly due to the battery charger. However, it did keep my lights going during most nights and encouraged me to consider a more sophisticated battery storage system.

Read the full article in ReNew 131.

High rise block switches to solar

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Residents in this high rise apartment block shared the cost of a 47.5kW solar system, costing around $230 upfront for each of the 290 owners.

The 47.5kW solar system is the largest ever retrofitted to a Melbourne apartment block with 190 solar panels.

The 47.5kW solar system is the largest ever retrofitted to a Melbourne apartment block with 190 solar panels.

 

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The owner’s corporation at a Docklands high-rise has installed the largest solar system ever retrofitted to a Melbourne apartment block.

The owners’ corporation at Yarra’s Edge Towers Two and Three in Lorimer Street took advantage of a $3000 rebate from the City of Melbourne and support from the national Smart Blocks program.

Councillor Arron Wood, Chair of the City of Melbourne’s Environment Portfolio said the initiative benefits the environment and the owner’s corporation.

“This huge 47.5kW solar system is the largest ever retrofitted to a Melbourne apartment block, with 190 solar panels converting sunlight into electricity. It’s not just the environment that is the winner here, it’s the 290 owners who will pay less to power the lighting and ventilation systems in their common areas,” said Cr Wood.

Owners Corporation member Peter Taylor said that while the system cost around $67,000, one of benefits of living in an apartment building is that costs are shared – around $230 upfront for each of the 290 owners.

“The final price was very affordable when we acted together and it’s an investment in the future value of the whole block. A lot of people think you can’t install solar in a high rise, but we’ve proved that you can and the savings are real,” Mr Taylor said.

Another medium rise apartment building in West Melbourne has installed a 10kW solar system that will save the owner’s corporation $2703 a year in electricity bills. A limited number of rebates of up to $3000 are still available for apartment buildings in the municipality to install solar electricity systems to power common areas.

Cr Wood said the Smart Blocks program supports the City of Melbourne’s goal to become a carbon neutral municipality by 2020. High-rise apartment dwellers consume more than 25 per cent more energy per person than those in a detached dwelling.

“To be a carbon neutral city by 2020 we need act smarter but we also need to empower residents to make our existing buildings more efficient,” Cr Wood said.

“Many of our residents are attracted to the inner city apartment lifestyle, but they also want to do their bit for the environment and reduce their power bills. This project shows apartment managers and owners can work together to improve the sustainability of their buildings,” said Cr Wood.

The solar systems were installed by commercial and residential solar installer Energy Matters with advice from Positive Charge. Find out more about Smart Blocks at www.smartblocks.com.au

Efergy

Know your renewables: meter matters

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In ReNew 126 we looked at electrical terms covering energy, power and other basic electrical concepts. Here, Lance Turner looks at common terms and concepts used to discuss energy metering and monitoring.

Whether your renewable energy system is grid-connected or off-grid, monitoring the system’s output is important to ensure it has a long and healthy life. Even if you don’t have a renewable energy system, understanding your energy usage is an important first step to becoming more energy efficient.

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There are a range of meters and gauges for all these uses. Here, we look at the most common types of meters, what they show, how they work and any limitations.

Electricity meter

First up is the electricity meter. These come in a number of types, including the older ‘spinning disk’ types and the more recent ‘smart meters’. The latter enable remote communications with your electricity retailer, so they don’t need to come out to read your meter, and provide much more fine-grained information on your electricity usage, including half-hourly data.

We’ve covered smart meters in detail in previous issues of ReNew (for example, ReNew 124) and in the ATA’s Smart Meter Consumer Guide (www.bit.ly/ATASMCG), so we won’t go into them in detail here. Suffice to say that both older meters and smart meters record electricity usage over a period in kilowatt-hours.

Interaction of your electricity meter with a grid-connected PV system

It’s important to note that most electricity meters now use net metering. A net meter will show electricity you imported from the grid and exported to the grid, but not the electricity your PV system generated that was used on-site. Some states originally used gross metering, which showed all electricity generated and all electricity used, but this has now been phased out in all states (though some older systems will still have this type of meter).

Net metering leads to an issue in calculating the total energy you are generating and using. To get these figures, you need to use the metering that comes with your renewable energy system, usually available both as a display meter and as a set of data that can be stored and downloaded from your inverter. Even if your system uses microinverters (small individual inverters attached to each panel), this data will usually be available through the microinverter manufacturer’s web portal.

Your inverter will provide you with the total PV generation figure (over a period of time), while your electricity meter will provide you with the energy imported from and exported to the grid. To calculate the total amount of electricity consumed by your house, simply add the import and generation figures and subtract the amount exported.

Read the full article in ReNew 130

off grid

Off-grid in the suburbs

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One ReNew reader has used his electric vehicle to take most of his energy consumption off-grid. He explains how he did it.

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I was keen to increase the size of my PV system as my house was using more energy than the system produced in winter. This meant I was importing energy from the grid at 29 c/kWh (100% GreenPower, I hasten to add!).

I was also keen to experiment with going off-grid. I considered going completely off-grid, but that would mean losing the perceived reliability of supply from the grid, requiring a leap of faith for a suburban consumer like me.

Off-grid economics

My solution, instead, was to install a separate off-grid PV system. I now have two PV arrays with separate inverters, one connected to the grid and one off-grid, with the house running (mainly) on the off-grid system.

The idea of going off-grid with battery systems was featured in ReNew 128. One article suggested that price parity with a grid connection is yet to arrive, particularly in metropolitan areas, as PV may now be cheap but batteries are still expensive.

However, I already had a good-sized (8 kWh) lithium ion battery in my plug-in Prius conversion. I was able to use this battery for my off-grid system, with it providing around 6 kWh storage at 75% depth of discharge. So, even though I live in metro Melbourne, the economics worked out well for me.

Technology needed

My system required some technology: I purchased a 4 kVA Ecotronics unit from Commodore Australia that does it all. It is a MPPT (maximum power point tracking) PV controller, battery charger, AC inverter and grid UPS all in one (see Products, this issue).

It is designed to run off a 48 volt battery, the same as my Prius PHEV conversion system battery. The conversion system, from Enginer in the USA, uses a 48 volt battery and a DC–DC converter to step the voltage up for the Prius’s drive system.

The Ecotronics unit can also automatically revert to grid power if there is not enough sun or the battery is low. It can even be set up for load levelling—i.e. charging the battery bank on night-rate mains power then supplying power during the day. However, with a relatively high night-rate tariff (19 c/kWh), the economics for this are marginal for me—a 10 c/kWh saving over the day rate of 29 c/kWh.

The Ecotronics unit simply connects to the Prius conversion’s 48 volt battery via a large Anderson connector (a high current rated two-pole connector popular in DC systems). When not running the house loads, the Prius battery can either be charged from the Ecotronics unit’s built-in battery charger or the charger that came with the Prius conversion kit.

Read the full article in ReNew 130

corena - Tulgeen 7kW 450

Community solar: energy from the ground up

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With support resources now readily available, Taryn Lane from Embark explains how individuals, groups and businesses can work together and benefit from setting up community solar projects.

Already a mainstream model internationally in countries such as Denmark, USA, Germany and Scotland, community solar is about to hit Australia in a big way. There are around 50 active projects in Australia and it is a tangible pathway for all communities—whether they be urban, regional or remote—to participate in transforming their energy supply.

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Community solar can take on a myriad of identities, depending on a community’s exact needs and opportunities. From community bulk-buy rooftop models, through to small crowd-funded systems, up to more sizable solar parks, they provide real opportunities for installation efficiencies and more inclusive ownership.

Several models of community-owned solar projects feasible within Australia’s current legislative and energy market boundaries will be explored in this article. Although we can learn from international models, we also have unique restrictions in the Australian landscape that we all need to navigate. Our aim at Embark is to both create innovative business models and collate from the broader sector what’s been learnt from the first generation of systems—thereby accelerating the uptake of, and social licence for, renewable energy in communities in Australia.

Why community solar?

The move to a low-carbon economy requires a magnitude of capital that charity alone cannot provide: community investment with reasonable returns will provide a necessary part of the solution.

There is still a significant portion of the community who can’t invest in solar technology. This includes renters, apartment owners, those living in homes with shaded roofs or heritage overlays, and those who can’t afford to install a residential system on their own home.

Community solar projects enable neighbourhoods to develop and own their own renewable energy infrastructure. It answers the calls for social equity for solar in Australia, as renters, apartment dwellers and low-income households can have the opportunity to make a direct investment in solar PV.

Shared ownership schemes will soon drive significant growth in the medium-scale solar space. A business installing 100 kW on a factory roof will result in the same abatement as a community that installs 100 kW in the same location, but the latter has the opportunity to engage a hundred (or more) community members on an ongoing basis.

Read the full article in ReNew 129.

Aussie Batts sinewave

As easy as DC to AC: inverter basics

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Almost all renewable energy systems use at least one inverter. But what exactly are they and how do they work? Lance Turner explains.

Solar panels produce DC electricity, and batteries store DC. However, common household appliances are all designed for the AC mains power grid and so can’t be used with DC electricity directly. The inverter solves this problem by converting DC into AC. There are a number of different types of inverters for different uses, and inverters have a number of different ratings that it is important to understand.

DC versus AC

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Firstly, let’s explain those two terms—DC and AC. DC is short for direct current. This means that current only flows in one direction. This is the type of current produced by batteries and solar panels. AC stands for alternating current. This is the type of current supplied by the mains power grid. It rapidly reverses direction 100 times per second and there are two reversals per cycle, so the mains grid frequency (in Australia) is 50 cycles per second, or 50 Hertz (Hz).

The reason AC is used in the mains grid is that, firstly, this is the type of electricity produced by rotating generators (more accurately called alternators) used to generate electricity in large power stations. Also, AC allows for simple voltage conversion using transformers, so power can be transported long distances at very high voltages and then stepped down using a simple transformer (basically a block of iron with some insulated copper windings wrapped around it) to voltages safe for domestic use. Converting DC to a different voltage takes a lot more effort— something that couldn’t be done efficiently when the grid was first designed. So too does converting DC to AC, but thanks to modern semiconductors, producing AC mains power from a DC source is now quite easy.

Inverter types

GRID-INTERACTIVE INVERTERS 

Grid-interactive inverters are now the most common type of inverter, with over 1 million of them installed across Australia as a part of rooftop solar systems. They take DC power from a renewable energy source, such as a solar panel array, and convert it into AC power.

Note that a grid-interactive inverter can’t supply power to the house if the mains grid is down. This is a safety feature called anti-islanding; it prevents export of power at the time of a grid failure, thus protecting people working on the powerlines. The inverter can’t just disconnect from the grid and still power the home as the output from the solar panels varies depending on conditions, so the inverter output is unknown at any given time. By shutting down, the inverter also prevents your appliances from being affected by fluctuations in voltage that could occur if powered directly

The power from grid-interactive inverters is used inside the home or, if you’re generating in excess of what you’re using, the excess gets fed in to the grid.

Microinverters are a subset of grid-interactive inverters. Rather than having one large inverter that all of the solar panels feed into (often called a string inverter), microinverters are tiny inverters that are mounted on the back of each solar panel. They only convert the energy from their own panel (or sometimes a pair of panels), so they are much smaller and lighter than a string inverter, and each microinverter feeds AC power independently into the grid/ home. This makes them better suited to some installations, such as when one or more panels in an array might be shaded or become dirty, as the reduced output from one panel has no effect on the rest.

Read the full article in ReNew 129.

Sunulator_logo

Sunulator solar calculator

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The ATA’s new tool for calculating the economics of solar installations can use half-hourly consumption and insolation data to give a much more accurate view of the benefits. Andrew Reddaway explains.

If you’re trying to get a community solar project off the ground, a major issue is economics. How much electricity would the system generate? What kind of deal might you offer the host site? What rate of return can investors expect, if any? To answer such questions, you need to do some homework.

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This is where you can use Sunulator, ATA’s free tool, which estimates the economic feasibility of a grid-connected solar photovoltaic system.

Is it like Tankulator?

Readers may be familiar with the ATA’s popular tool at tankulator.ata.org.au. Just as Tankulator helps you plan for a rainwater tank based on historical rainfall data, Sunulator helps you plan a solar system based on sunshine data. However, there are more variables in solar systems, so Sunulator had to be more complex.

How it works

Sunulator uses a simulation approach. You provide information on the host site’s current electricity consumption, ideally for a full year. You also tell Sunulator some details on the proposed solar system, electricity tariffs and costs. Sunulator then simulates a year in half-hourly intervals.

For each interval it determines the position of the sun in the sky and estimates electricity generation, based on sunlight intensity and the angle at which it hits the solar panels. It then compares this generation to on-site electricity consumption to estimate the amount of electricity imported from the grid and/or exported to the grid. Finally it applies the tariffs to calculate the interval’s contribution to the annual electricity bill.

A key result from this simulation is the overall percentage of solar generation that gets exported to the grid rather than consumed on-site. For example, 15% of generation might be exported, or it might be 70%. This percentage has a big impact on economic feasibility, as the typical value of exports (via feed-in tariffs) is only a third to a fifth of the value of electricity consumed on-site. Most other solar calculators require you to estimate this percentage, whereas Sunulator calculates it based on electricity consumption versus simulated solar generation.

After the detailed simulation is complete, Sunulator totals the annual generation, bill savings and investor returns and extrapolates them up to 35 years into the future, based on user-defined future changes in tariffs etc. This future cash flow is used to calculate economic measures such as return on investment, net present value and payback period.

Electricity consumption data

You have a couple of options to provide consumption data. Ideally you will have access to data from the host site’s electricity meter, in which case you can format it in another spreadsheet, then copy and paste it into Sunulator. If not, Sunulator will help you to construct data from estimated monthly and daily profiles.

Climate data and locations

Sunulator is currently setup to work for sites in NSW and Victoria (as the funding for its development came from organisations in those states). ATA selected a total of 45 locations throughout NSW and Victoria based on population, climate variability and proximity to an automatic weather station. For each location, we extracted satellite-based hourly sunshine data purchased from the Australian Bureau of Meteorology from the 1990s up to the end of 2013. Months with too much missing data were excluded. We filled gaps in the remaining data and interpolated to half-hourly values.

We then prepared a typical meteorological year (TMY) for each location. For a TMY, each of the twelve months of the year is considered separately. Data is not averaged, as that would understate the variability in actual sunshine. Instead, the most typical full month from the data set is selected.

Let’s say 10 years of sunshine data are available. Each of the ten Januarys has its sunshine totalled, and the average of these ten figures is calculated. The January whose total sunshine is closest to the average (e.g. January 2000) is selected. Then we move to February. For example, the February data might be copied from February 2013, if that was the most typical February. This results in a full year of data made up from months selected from several different years.

Scenarios

In Sunulator you can define up to six different scenarios for comparison. One is the ‘business as usual’ scenario, which typically has no solar system. In the other scenarios you can explore a range of options for a solar system, for example varying system size or tilt angle. Or you might consider the impact of different system installation costs or electricity tariffs.

When you run Sunulator it calculates all the scenarios at once, and you can then compare the different scenarios side-by-side.

Testing

ATA was fortunate to obtain assistance from several volunteers. They ran simulations for a range of locations using 2013 sunshine data and compared Sunulator’s results to reported actual 2013 generation data from the website Pvoutput.org. Often, reported data was influenced by site-specific factors (e.g. shading from trees or buildings). An intriguing example was Falls Creek—some sunny winter days matched very well, but others did not. After much head-scratching, we realised it was likely due to snow lying on the solar panels! This reinforces an important point: don’t rely on Sunulator alone, make sure you carefully consider local conditions. On the other hand, some sites gave very ‘clean’ matches.

We also checked Sunulator’s generation estimates against some other solar calculators and found a good match when looking at aggregate results.

Community investment options

Although most solar installations in Australia are owned directly by the electricity consumer, Sunulator is designed to assist community organisations to install solar systems via additional investment options. For example, it might be used by a community organisation planning to install a system and sell electricity to the host site, or to install a system through a loan, or for a community organisation acting as an electricity retailer. There’s more info on the different ways it could be used on the Sunulator page, in the presentation links.

Can a homeowner use Sunulator?

Sunulator is very suitable for estimating economic feasibility of a grid-connected home solar system. However, it does require some persistence and prior knowledge to use it effectively. It also requires a computer with Microsoft Excel 2003 or later. Please see the user manual for more details.

Future development

As useful as Sunulator is, it could be improved! If funding permits, our first priority is to extend Sunulator to all states and territories. Battery storage would be an important enhancement, allowing users to evaluate the economics of battery-enabled grid-connect solar systems. As covered in ReNew 128, these are already commercially available and receiving a lot of interest.

For more information, including a full user guide: www.ata.org.au/ata-research/sunulator

The ATA has run two training courses so far and hopes to hold other training courses and publish an online webinar. Keep an eye on the ATA website for updates.

inveters

Microinverter potential: your questions answered

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Are microinverters a passing fad or a serious contender in the solar inverter market? Industry analyst Nigel Morris from Solar Business Services looks at some of the common issues people ask him about.

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A microinverter is quite simply a very small inverter which converts DC electricity from solar panels into AC. The major difference between micro and string inverters is that microinverters convert the power from each solar panel individually, whereas string inverters convert the energy from a string of solar panels connected together in series. Microinverters are typically attached to the back of a solar panel whereas string inverters are usually mounted on the wall near your switchboard.

There are pros and cons to each type of technology, but after being involved in the industry for more than 20 years, one thing is clear: microinverters have a rightful place— and that place is growing.

A good place to start with the microinverter story is a bit of history. Many people don’t realise that they have been around for a long time; my former employer was supplying a company who successfully sold them in the late 1990s. True, they struggled a bit with reliability but the majority are still out there plugging away on Australian roofs. So they aren’t new and there has been some good long-term experience with the technology.

Having said this, string inverters have dominated sales and it’s only in the last few years that microinverters have come back with a vengeance. So what’s changed?

Clearly, technology has evolved a lot in the last 20 years.

It stands to reason that both string and microinverters have benefitted from this evolution. However, it could be argued that, in recent years, miniaturisation and electronics development has had a far bigger impact on the potential for microinverters, and that’s part of the reason they have taken off.

To put it in context, around 40% of all inverters sold in California (one of the world’s largest residential solar markets) are now microinverters, and locally, more than 10% of all sales are now microinverters. The world’s biggest microinverter company recently announced it had sold its five millionth microinverter; so the numbers are becoming very substantial.

To help understand more about microinverters, here are the issues I am most often asked about.

1: “It’s really hot on the roof. It doesn’t make sense to put electronics there and their life must be shorter as a result.” 

This is sound logic and pretty rational thinking. However, the reality is that well-designed microinverters can deal with this stress and most have 10 to 20 year warranties as standard. The big companies making good products recognised this challenge and set out to build in very high levels of quality and so dominate the market. Also, being smaller, microinverters don’t create or have to dissipate as much heat.

There are also a number of independent studies that demonstrate how microinverters perform under high-temperature situations which show that the reliability is very high.

With the better companies, we are also seeing very large-scale, micro-level manufacturing, which lends itself to really sophisticated quality systems; many are working with the same companies who make smart phones, as an example. One manufacturer also described to me how, by monitoring so many microinverters around the world remotely, they can feed back the data into their processes in almost real-time—a perpetual and real-time quality feedback loop.

So, these inverters are very sophisticated and can cope with high temperatures.

Read the full article in ReNew 129.

Disclosure: Solar Business Services consults to government, installers, retailers, wholesalers and manufacturers of solar equipment, including microinverters. This article was not paid for by any manufacturer and was produced at the request of the ATA.
IMG_5557 400px

No wires and too much power!

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Kevin White describes his off-grid home in Queensland as a renewable energy ‘power station’, with more energy than they can use!

It all began with eighty-three acres in southeast Queensland, an almost clean slate, up for sale by a good friend who’d fallen in love and was emigrating. Suddenly we had acquired a property with a bit of everything— dairy pastures running out to steeply treed hills, peaking at a ridge before descending into remnant rainforest; a 300-foot hill rising from the flats completes the picture.

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Buying the property was the easy bit; deciding what to do with it was more evolution than plan. The flats had been used for grazing so we decided to continue that. In went cattle yards and a reasonably large shed—your shed can never be big enough! We decided to build a studio within the shed as temporary accommodation while we planned our build.

As ex-yachties who’d swallowed the anchor for the country life, we knew we wanted to maintain our independence. The ‘reasonably large shed’ had plenty of roof area to supply a water tank and there was plenty of fallen timber nearby for heating.

We wired the studio for both 12 and 240 volt power. We had no idea where on the property we wanted to build so we didn’t consider getting a quote for grid power at the time. However, we did get a telephone connection put into the shed.

At that time (just a few years ago!), solar panels were a rather costly item, so for our interim system we decided to mount four 80 W panels on a frame and have them track the sun for peak efficiency, along with using an MPPT charge controller and 400 Ah of Trojan T105 batteries.

Being an ex-electronics tech I built the tracking system—from an old C-band satellite dish mount, coupled to a homemade trackin  controller. ‘Noddy’ did his duty, day in and day out. We were always delighted when guests asked, “Did your solar panels just move?”

With 12 volt LED lighting, a modest 12 volt fridge/freezer, 12 volt entertainment devices, a laptop and a pot belly stove (with a year’s worth of cut timber), my tolerant wife Gudrun spent over a year living in our temporary home while I went to work in Antarctica for a year.

Read the full article in ReNew 128