Enphase AC Battery comes to Geelong


Enphase storage system

Enphase solar AC battery set to shake things up

Solar Microinverter manufacturer, Enphase Energy is set to release their new AC battery to Australia in August and last week they confirmed special pricing for a limited number of units for pre-sale.

We’re pretty excited here at Green Energy Options, we think that Enphase have a unique battery storage solution that could be a game changer in the way residential battery storage is done.  Their AC battery enclosure includes a 1.2kWh Lithium Ferrite Phosphate battery and a microinverter which is AC coupled to provide 240V AC power to appliances in the home.

With a large number of solar home batteries hitting the Australian market in recent months it’s hard to know which way to look. Electric car manufacturer, Tesla have managed to capture the mainstream’s attention with their Tesla Powerwall home battery and other major electronics companies like LG, Samsung, Sony and Panasonic have also entered the market.

So, what’s so good about Enphase’s AC battery? I hear you ask.

Well, Enphase are making home battery storage more affordable and easier to install than ever before and here’s a few reasons why we think it’s great.


Probably the thing we like the most about the Enphase AC battery is that it’s small and modular. Each unit is 1.2kWh of total storage capacity (1.1kWh usable) meaning that you can start off small and expand the system as you go.  Most other batteries are much larger in the 3-10kWh range, meaning that the starting price is higher and the size is often larger than what’s required.


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Flexible Design

When it comes to designing a storage system to suit your circumstances, this modularity allows for flexibility that other battery systems don’t. Remember that to get the most financial benefit out of your battery storage system; you really want to be cycling the battery to its full capacity every day within the warranty period. This means you need enough excess solar to charge the battery during the day and that you want to be using enough electricity in the evenings to draw down the battery to its full capacity too.

Now as there will always be times when you are away, out for dinner or not consuming enough energy at night, the larger your battery storage system is, the more likely it will be to have battery capacity sitting there, that you’ve paid for, that’s not being used. The Enphase AC battery allows us to design the right sized system to suit you.


Enphase’s AC battery system allows a low price point for entry that isn’t possible with other battery storage solutions. The speed and ease of installation is another factor that contributes to keeping costs down, with a single unit able to be installed in around half an hour.

People wanting to start with a small battery system and grow it are now able to enter with a price point starting at under $2,500 fully installed (for one unit), with the price reducing for additional units. This now makes it highly accessible for many homeowners around Geelong.


The Enphase AC battery will be compatible with any existing solar system, it won’t matter if you have an Enphase microinverter system or a traditional string inverter system, it will work. This means you won’t need to replace your existing inverter or install a separate battery charging inverter for the batteries.

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Enphase have shown with their microinverters that they can manufacture at scale with a very low failure rate, while maintaining a high quality product that lasts. With a 10 year warranty on their AC battery, based on cycling the battery twice a day, Enphase probably have one of the cheapest battery storage systems in cost per warranted kWh.


  • Enphase’s AC Battery system uses prismatic cells from leading Japanese battery manufacturer Eliiy Power, which are very stable over time.
  • The battery doesn’t have any high voltage DC in the system
  • Safety certified by independent German certification body TUV Rheinland

Probably a couple of things worth noting with this battery is;

  1. That it is designed to capture the main value proposition for grid connected solar customers; capturing excess solar rather than exporting it to the grid. If you are after a battery that provides backup if the grid goes down, this is not currently a solution that will be able to do this. If backup is what you’re after, give us a call, we have other solutions that will be more appropriate.
  2. You will need to install an Enphase Envoy-S-Metered, which is the smart controller that monitors and manages the energy coming from the solar and being stored in the battery, as well as when the energy is discharged. The Envoy also doubles as a solar and consumption monitor and these are normally installed in a separate switchboard or hub in a garage or near the switchboard.

 With a background in manufacturing solar microinverters, Enphase have always stated that they are an energy company, with a vision for a whole of home energy solution. This is one of the things that excites me most, as they are looking not only at solar and battery storage, but beyond this towards the smart home and the clever energy management of appliances.

With so many benefits, and the first shipment of Enphase batteries coming to Australia in August, we expect there to be a swift uptake of the Enphase AC battery. Call us now on 1300 931 929 to pre-order your own Enphase AC battery.


For more information on the enphase home battery storage visit the website:


Installation of battery


Business to benefit from solar budget boost


Business in Geelong and the Surfcoast can install solar and benefit from tax break. Call us on 1300 931 929 for more info.

Businesses looking to invest in solar power have been given further incentive with changes announced in the budget last week.

The Federal Government have announced an increase to the turnover threshold for businesses wanting to take advantage of immediate tax deductions for business equipment – like solar power systems- up to $20,000.

Currently businesses with a turnover of $2 Million annually can take advantage of this scheme.

Changes to the budget mean that from July 1st 2016, businesses eligible for this tax write off will be increased to $10 Million.

This could turn out to be a big help for savvy businesses who have been considering using solar to get their overheads down, increase their cash flow and bottom line.

Many businesses tend to use their electricity between the hours of 9am to 5pm – the ideal times of day for a solar system to generate electricity. With the reduction in feed in tariff rates, installing solar is all about being able to self-consume your solar energy on site and offset the cost of purchasing electricity from the grid. We’re already seeing businesses saving thousands of dollars a year on their electricity bills.

Most commercial systems that we install have a financial payback of 4-5 years, but we would expect the instant tax deduction to reduce that further. Solar power systems have an expected system life of 20-25 years, so the system will continue to provide savings well beyond the payback period.


In summary

Invest in a solar system up to $20,000 ex GST. You can get a good quality 10-15kW solar system.

  • Claim the entire cost of the system as an immediate tax write-off.
  • Slash your electricity costs more or less overnight – Many businesses are using a large amount of their power during the day when the sun is shining.
  • With the huge savings made, pay off the remainder of your system in 2-5 years.
  •  Gain additional savings on your power bill over the next 20-25* years therefore increasing your cash flow and your bottom line.


*Expected life system of most solar systems

Solar Mounting Systems

Geelong Solar Mounting Systems

One of the least sexy and often overlooked components of a solar power system is the solar mounting system that attaches the panels to the roof or the ground. This is sometimes referred to as a racking, framing or railing system. The mounting system is a pretty important part of a solar system and all mounting systems need to be supplied with an engineering certificate showing they comply with the relevant standards.

At Green Energy Options we think there are a number of benefits that come from using a high quality mounting system, here’s a few examples:

  1. It provides peace of mind that the panels are secure and won’t be blown away in strong winds.
  2. It improves the performance of your solar system, through good airflow around the panels and/or optimising the angle of the solar array.
  3. Minimises potential for corrosion and in turn reduces maintenance costs and helps improve the return on investment of your system.
  4. If there are problems, questions or warranty issues, having a reputable, responsive, local business to deal with is important.

Green Energy Options use the Sunlock mounting systems on our solar installations. Sunlock’s documentation on installation and engineering requirements is probably the most detailed available for rooftop installations in Australia and is backed by a 10 year warranty. Best of all, its Australian made, manufactured right here in Melbourne by Ullrich aluminium. Here are some examples of Sunlock’s fixings for different roof types:

Standard corrugated tin roof

On a standard corrugated tin roof an L-foot is usually used. It attaches into the top ridge of the corrugation and is isolated from the tin by a rubber pad to stop water ingress and electrochemical corrosion between dissimilar metals.

Sunlock L Foot

Tile bracket

On a tile roof, there is no need to drill through every tile, we simply lift the tile, attach the tile bracket to the rafter and slide the top tile back into place. The tile bracket’s arm fits between the two tiles and the rail is then attached to the bracket’s upright arm.

Solar Tile Bracket

Tilt frame

Tilt frames are normally used on flat rooves or rooves with a low pitch. By tilting the panels up towards the north to a steeper angle you are able to optimise the output of your system. Note that tilt framing adds a cost to the solar system so it’s not always the best option for increasing energy harvest. Sometimes it will work out better to spend the money on adding an extra couple of panels to increase output. Green Energy Options is happy to assist you with working out what will be best for your home or business.

Soalr tilt frames geelong

EcoGeneration has also put together a guide called The Australian Mounting System Guide, this provides a great overview of what to look out for in a solar mounting system. Ecogeneration Mounting Systems Guide

For further information, please feel free to contact us on 1300 931 929

Oversizing your solar array

Oversizing your solar array

Oversizing your solar array in comparison to the size of your solar inverter can be a great way to generate the most kWh from your solar power system at the best price. It sounds counterintuitive when you first hear it; installing a 6.5kW solar array on a 5kW inverter seems like an inefficient way to design a solar system, but rather than using the term oversizing, I’d suggest it’s more like optimising or supersizing your system. There are boundaries and limits to how far you can go, but in many cases I think it can be a good idea.

Firstly I must mention that this isn’t appropriate with all solar inverters, so before you do anything, check with the inverter manufacturer (or your local solar installer) to make sure their inverters are designed to cope with oversizing your solar array. Green Energy Options has experience in oversizing solar arrays and can advise of which inverters are most appropriate.

Why Oversize?

The price of Photovoltaic (PV) solar modules has dropped dramatically over the last few years, so it is now much cheaper to add additional solar array capacity. The idea is that rather than putting money into additional inverter capacity put your dollars into extra panels and you’ll see a better energy harvest and better financial result.

To explain why, I’ll start with the nameplate rating of a solar PV panel; a 260 Watt panel for example is a power output that’s achieved in a lab under Standard Test Conditions (STC) that is at 25 degrees Celsius and 1000W/m2 of irradiance. In reality the panel will rarely put out 260W of power because of system losses. For much of the time the panel’s operating temperature will be more like 40-65 degrees and heat inhibits the panel’s output a little, cloud cover can also mean the system won’t be performing at i’s peak or the angle of the sun in relation to the panel can contribute to a reduced output. We also need to bear in mind that over time the silicon in the module will degrade and dirt and dust build up can reduce output too.  Under these circumstances where a solar panel or a solar array isn’t performing at its peak output very often, the top end of the inverter’s output range is rarely used.

Oversizing Enphase micro-inverters

Enphase Energy recommends oversizing panels in relation to their micro-inverters, they recommend using panels up to 270 Watts on their 215 Watt micro-inverter. Below they show in a graph that the losses from ‘inverter clipping’ are mostly below 0.5% (when the panel output is above the peak inverter capacity). This is by far outweighed by the additional production that you get from having a larger panel, up to 12% increased output. In essence the same theory goes for larger string inverters too; Fronius state that their Galvo range of inverters can be oversized by 100% of the inverters nameplate capacity, as long as other conditions are met and their warranty is still upheld.

Enphase Oversizing Graph


Clean Energy Council Guidelines

One thing that needs to be kept in mind is the Clean Energy Council’s (CEC) design and installation guidelines, where they state that ‘In order to facilitate the efficient design of PV systems the inverter nominal AC power output cannot be less than 75% of the array peak power and it shall not be outside the inverter manufacturer’s maximum allowable array size specifications.’ In other words the array size cannot be more than 133% of the nominal inverter power rating.

Powercor is the electricity distributor for Western Victoria, this includes Geelong, the Surfcoast, Bellarine and some western suburbs of Melbourne. Powercor have a 5kW inverter limit for single phase connections. In a scenario, where you are a high energy consumer and would like to install a larger solar array to maximise the benefit of your solar system, we can theoretically oversize your solar array to 133% or 6.65kW and still be within the CEC guidelines.

Analysing Costs

An analysis done by our Friends at AC Solar Warehouse show that a high quality 260W solar module paired with an Enphase M215 micro-inverter (peak output 225 Watts), would see clipping of 0.01125kWh on the best day of the year. They went on to say that there was approximately 12 weeks of the year that saw some clipping and that this worked out to be about 0.987kWh of lost production. Offsetting at $0.30c/kWh it works out to be a loss of 29.6 cents per module. This amount is pretty small, particularly when you way up the alternative cost of a larger capacity inverter, there’s no benefit in selecting micro-inverters that increase the cost of the system by $30 per module, in order to harvest an extra 29.6 cents per year. That’s a 100 year payback.

Oversizing and inverter life

Just one final note, oversizing your solar array means that the inverter will be running at its peak output for a larger portion of its life. This can cause components to heat up and run hotter and in some cases have a shorter life expectancy. The good news is that many inverters have systems in place to manage excessive heat build-up and protect heat sensitive components; most will even shut themselves down in extreme cases. Good inverter placement allowing appropriate cooling and ventilation can help to optimise inverter life expectancy, talk to your solar installer about the best place to position your inverter.

For any questions about optimising, supersizing or oversizing your solar array please feel free to give us a call on 1300 931 929.

Aaron Lewtas

Green Energy Options






5 Ways to Improve Solar Self Consumption

When it comes to installing a solar power system, solar self consumption is the name of the game these days. With Victoria adjusting its Feed in Tariff (FIT) to 6.2 cents/kWh on January 1st there’s not a lot of incentive to export your freshly harvested sunshine energy back into the grid, just so your electricity retailer can mark it up and sell it to your neighbour. From an economic point of view, it’s much better to consume that sun power on site and offset the cost of you having to purchase electricity from the grid at 25-30+ cents/kWh.

If you are a home or business consuming electricity during daylight hours and can self-consume all the solar energy spilling off your roof, it’s great, you can get good value from a solar power system and you might pay your system off in 4-5 years. If not you may be exposed to exporting a larger portion of your solar electricity at a low rate, pushing out your payback period.

There are a few things that you can do to increase solar self consumption from your solar power system. They range from no-cost behavioral change to energy management options and more expensive battery storage solutions. Here’s five ways you can improve your financial return on your solar system by optimising self-consumption from your rooftop.

  1. Change the times when you use electricity

The no-cost way to maximise consumption of your solar energy generation is to change the times that you use appliances. If you are able to modify your electricity consumption patterns so that you are consuming more electricity during the middle of the day when the sun is shining, you will help to minimise your solar export. Offsetting at 30c/kWh is better than exporting at 6c/kWh. Remember this is not an exact science and it won’t work for all households or all appliances, but if you can turn your dishwasher on at lunchtime, do the washing during the middle of the day or turn the air conditioner on when the sun’s out, it will be beneficial towards the financial savings you’ll get from your solar system. What I always say to our customers is “don’t turn your life upside down for your solar system, just be aware of how it operates and take advantage of it where you can”.

  1. Use a timer

Installing a timer can be a good low cost way to co-ordinate appliances to come on during daylight hours. Obviously it won’t work for all appliances, but pool or spa pumps, water pumps, and in some cases even heaters or hot water systems can be put on a timer so that their time of operation coincides with solar production. Some appliances like dishwashers and washing machines will even have a built in timer that will allow you to program when they come on. Again this isn’t the perfect solution, because if it is overcast and your solar system isn’t producing a lot of power and your pool pump is running, you will be purchasing the excess power from the grid probably at peak rate. But if your pool pump was running on peak rate anyway, it’s going to be better to have it more closely matching with solar generation times. If an appliance was running on an off-peak rate there’s probably a deeper analysis required.

  1. Solar inverter with energy management relay

Some inverters are now incorporating smart energy management functions in them that allow for optimised solar self consumption of your solar energy. Austrian inverter manufacturer, Fronius is one company that has been leading the charge here. They have integrated an energy management relay into their new range of inverters the Fronius Glavo and Fronius Symo.

Fronius Galvo Solar inverter

Fronius Galvo Solar inverter

The energy management relay inside the Fonius inverter can divert solar power to a specific appliance and help avoid exporting at a low feed in tariff. All we need to do is set a power value of say 2000 Watts and once your solar starts generating more than the pre-set amount, it will flick a switch and turn on your pool pump to soak up the solar generation. A second pre-set amount can be set e.g. 1800 Watts and when then solar drops below that point the inverter deactivates the power to the pool pump. This can be a great feature at no additional cost, but it also has its limits, similar to the timer solution, if the solar inverter is putting out 2200 Watts and there are other electrical appliances being used in the house on top of the pool pump consumption, you may find that you have a total power consumption of 3000 Watts for example. This would mean that the additional 800 Watts that wasn’t being supplied from solar would be purchased from the grid at peak rate. Once again one thing that needs to be looked at is the benefit of reducing export at a low rate, verses, buying electricity from the grid at peak rate that may have been previously purchased at off-peak rate.

  1. Third Party Energy Management Options

There are a number of new products coming out that allow you to have a bit more control over how much electricity you are importing and exporting. We expect to see many more hardware and software solutions hitting the market over the next few years that look specifically at this area. The immerSUN and ASM SunnyMate are two products that are currently available that look mainly at dealing with your hot water requirements.

immerSUN Solar Energy Management Device

immerSUN Solar Energy Management Device

Rather than just flicking a switch when the solar output reaches a certain point, these devices measure when you start to export electricity to the grid and will turn your electric hot water heater on to soak up any excess solar power, rather than having it exported to the grid for nix. In the case of an electric hot water unit, there are a couple of important factors to consider that are a little different from most other appliances. Firstly they are normally being run on off-peak electricity commonly around 15c/kWh around the Geelong region, and secondly the elements can range from 2400W -3600W quite a high power requirement. By using the immerSUN device you maximise the amount of self-consumed electricity by diverting solar to the hot water element, offsetting the cost of paying off-peak rates (if you had powered it from the grid at night), but at the same time the device minimises the electricity you have to purchase at peak rates to supply power to the hot water service during the day. The immerSUN actually has three outputs, allowing you to control two resistive loads like heaters or hot water units and one multifunction relay, which could be used to drive a pump for example.

The cost of having these units installed is starting to get a bit more expensive than the previous solutions, probably up around the $800-$1200 mark, so this isn’t going to be for everyone. As a general rule, the larger the disparity between your off-peak rate and the solar feed in a rate the bigger your savings will be. For example, an average electric hot water service takes about 8kWh to heat. Here’s a possible scenario:

Feed in Tariff = 6.2 cents/kWh

Off-peak tariff = 15 cents/kWh

Difference = 8.8 cents/kWh


8.6 cents x 8kWh (energy to heat hot water) = 70.4c/day savings

70.4 cents x 365 days = $256.96 per/yr savings

This case gives a 3-5 year payback on the unit, so could be a good solution to save money. This example does assume that there is enough solar power to heat your hot water unit each day, this is quite possible with a 5kW solar array, although there may be some boosting required from off-peak mains grid required on days of low production, which may reduce the savings a little. If the difference between your off-peak tariff and feed in tariff is less, then the savings seen will also be less.

  1. Battery Storage Solutions

There has been a lot of interest in grid-battery storage solutions for grid-connect solar systems lately. There are heaps of new products coming onto the market and costs are expected to come down over the coming years. Batteries can be another way that you can increase your solar self consumption. Rather than sending that power back to the grid at a low feed-in rate, store it in your batteries and use it at night. The technology is available to do this now and more and more people are beginning to take this option up. When compared to the other options listed above, there’s a bit of a price jump. Most decent battery storage solutions will add $13,000-$20,000+ to the cost of a solar system, depending on the amount of storage capacity you are looking for and the quality of the system, but with people getting fed up with being treated badly by their electrical retailer and not getting paid much for their solar export, batteries are a solution that many Australians are looking towards to gain more energy independence.

Battery storage solutions for solar self-consumption

Battery storage solutions for solar self-consumption

As I said earlier self-consumption is important when it comes to solar power. Many people have been ill advised about the savings that they will see from their solar system, mainly due to a misunderstanding about how the feed in tariff works. That’s why it’s important to do your research and get good advice about system sizing. Oversizing your solar system may just lead to additional exports and at 6.2c/kWh it might be better to go for a slightly smaller solar array and keep some cash in your pocket. Alternately if you are able to optimise your self-consumption efficiently through the solutions described above, you’ll be able to squeeze more value out of your solar system and keep more dollars in your pocket. Smart new technologies are set to change the way we use energy into the future, whether it be solar power, energy management solutions or the integration of electric cars into our electricity network, we are in for an exciting period – I think you can expect to see our energy network revolutionised over the next 10 years.

Note that for those solar consumers that installed their systems under the Premium Feed in Tariff or Transitional Feed in Tariff for solar, the above scenarios will not be relevant. If your feed in tariff is higher than what you are paying for electricity you will see a larger savings by exporting electricity to the grid than self consuming.

For advice on solar power, energy efficiency or anything outlined in the post above, please feel free to give us a call on 1300 931 929.

Energy Efficient, Solar Home for under $250,000

Holly and I have been keen to open our house for Sustainable House Day the last couple of years, but we’ve always had some excuses, a new baby, a lack of landscaping, too busy….. This year we bit the bullet and said yes. Our house in Torquay is a passive solar, solar powered energy efficient partly sustainable design. Four years ago we were first home buyers and we wanted to have a house that was comfortable, functional and cheap to run, but we, like many other first home buyers were on a budget. I wanted to be able to prove that it was possible to build an energy efficient home on a budget, and not have to make compromises on our lifestyle or comfort. After all the majority of Australian homes are not grand designed, architectural masterpieces. In the end our budget ran out around $230,000 for the house, although we have still a little work to do around the garden, we thought that this was pretty reasonable, and an achievable option for many Australians wanting to build a new home. I probably should give you the heads up now, that this is a longish article.

Solar House

We’ve been in the house now for a little over three years, there are always new things that we would like to do and there are some things that if I had my time again I would do differently, but on the whole we’re very happy with it. We were in the house for a few months’ pre-solar power system and pre-baby and our electricity consumption sat around 4kWhs/day (Kilowatt Hours). Since then we installed a 2.47kW solar system, which generates an average of 11kWh/day. Since we’ve had Ruby our consumption has gone up 1-2kWhs/day, mainly due to more washing and my wife, Holly, being home some days (doing more baking). So our current electricity consumption is about 5-6kWh day, 2kWh of which is being supplied from our 2.5kW solar system, the other 9kWh/day of solar energy that’s generated goes into the grid at 70 cents. Our electricity retailer has been depositing about $1500 a year into our bank account for the electricity we are exporting from the solar system. Any energy we purchase from the retailer is 100% Greenpower too, so although this doesn’t directly power our home it does go towards supporting renewable energy sources. We also have mains gas connected to our Solar Hot Water boost, cooktop and Rinnai Energysaver space heater. Our gas consumption varies quite a bit, from 5-25MJ/day (MegaJoules) during the spring, summer and autumn months through to 40-100MJ/day during winter (the 100MJ bill was the first winter with a newborn). Our bimonthly gas bills range from $30 in summer to $90 in winter.

We built our home through Pivot Homes in Geelong and I think in the end we got a 6.8 star rating for energy efficiency. Pivot were patient with us on the many sustainable design requests that we had and although some of these things were new concepts for them and we had to push them in some areas, we were very pleased with the final outcome. Our home is about 16 squares (150m2) plus the double garage, we found that looking at display homes and talking to a number of builders that the “McMansion” is alive and well in Australia and it was uncommon to find plans for houses under 20 squares. Sizing the house to our needs was important and by keeping a smaller floor space, it allowed us to spend money on other features. It’s basically a three bedroom home with one large open plan living and kitchen area on the north side, two bathrooms, a laundry and a double garage. I work from home and use one of the bedrooms as an office space. Now that Ruby is approaching 18 months, I’m being told that if we have another baby I might need to look for a new office, but at the moment space wise things are still good, the only thing we may be wishing in a few years is that we had built in a study, only time will tell.

Photovoltaic Solar Power System

Because I’m in the solar industry, and I am passionate about renewable energy, a photovoltaic (PV) solar system was always going to be a feature of the house. We installed a 2.47kW CIS (Copper, Indium, Selenium) thin film system, composed of 30 x 82.5W smaller than average modules on our north facing 20 degree pitched roof. The panels were manufactured by Japanese company Solar Frontier and our inverter is a Sunny Boy SB3800 from the trusted German manufacturer SMA. We got a pretty good price for a premium system at the time of about $9,000 (solar system costs have roughly halved since then) and we’re very happy with the system’s performance, pumping out an average of 10.86kWh/day at an efficiency of 4.397kWh/kW. The CIS panels have a special light soaking feature, where they are flash tested off the production line at 82.5W each, but once exposed to sunlight the actual power rating will increase, exceeding the panel’s badge plate rating. Even after nearly three years on the roof, our system on sunny days quite often produces over 3000W of power, I’ve even seen it up as high as 3300W, from a system rated at 2470W it is a great result. So the system is going great guns, but one thing I should mention is that things have changed a bit in the solar industry. The huge reductions seen in the price of crystalline modules over the last couple of years, in combination with the larger number of panels and surface area that thin film systems require mean that it is getting harder for some thin film technologies to compete. Extra costs for panels, racking, installation and fuses come into play. You can now install a larger crystalline system to improve your system’s output at a lower cost than going down the thin film path in most residential scenarios.

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Solar Hot Water

As well as installing a solar power system we also installed a gas boosted solar hot water system (SHW). We chose an evacuated tube system from AAE, 30 tubes tilted up to 60 degrees to optimise the system for winter sun; generally you will get plenty of heating in the summer months, but require boosting from the gas in the winter months. We went with a gas booster and a 315L stainless steel tank for longevity.

Passive Solar Principles

Passive solar design can play a huge role in the thermal performance of your home, orientation, window positioning, shading, ventilation, insulation and thermal mass all are important things to consider. Although our place isn’t perfect we think we got a few of these things right. I found that the www.yourhome.gov.au website and Renew magazine from the Alternative Technology Association were both fantastic resources for doing research into what things we needed to consider as well as getting inspiration and ideas. We put our living area on the north side of the house and tried to include as many north facing, big double glazed windows as we could to let the winter sun in. We also included one meter eaves on the north side to block out the hot summer sun. This keeps the sun from coming in the windows or hitting our slab in the hottest summer months, but allows the low winter sun through to heat the home when it’s cooler. We also went with a concrete slab for the whole house to help include thermal mass in the design. The concrete is good because it is generally cooler than the air temperature in summer helping to cool the house, and warmer than the air temperature in winter (especially the polished parts exposed to direct sunlight) helping to heat the house. For the outside walls we opted for rendered foam cladding, which has a high insulation value; on top of this we used R2.5 insulation in the walls and R3.5 insulation in the ceiling. The insulation is great as it helps us to contain any heat in the house in the winter as well as insulate ourselves from the outside summer heat.

Heating & Cooling

We didn’t include an air conditioner in the house to begin with, because I expected that we wouldn’t need one, I’m also aware of the large cost that air conditioners place on the electricity grid by increasing peak demand on hot days, this is one of the reasons for much complained about increasing electricity bills. So far weave lasted two summers with minimal discomfort and I’m feeling vindicated. Temperature wise our home normally sits between 17-23 degrees with the highest and lowest temperatures I’ve seen registering at 27 and 14 degrees respectively. We only have one gas space heater in our living area; it’s not really used for eight months of the year, but takes the edge off the winter chill for us when needed, which is usually only winter mornings and evenings as the sun generally heats the house enough during the day. The space heater actually works well enough for us to provide some heat to the bedrooms before we go to bed by opening the hall door and letting the heat travel down the hall. There are also two ceiling fans in the living area and one in the main bedroom; these are helpful mainly on hot days to make us feel cooler.

The positioning of the double garage on the south-west corner of the house was done on purpose to help insulate us against the hot summer afternoon sun; there are also no windows on the west side of the house for the same reason. We do have some cross ventilation from north to south, which we sometimes use to flush out the heat on summer evenings, we just have to make sure the hallway door is chocked, because otherwise you will hear a big BANG as the wind slams the door shut.

Energy Efficient Appliances

Appliances were one of the other things that we had to consider and on moving into our new house we purchased a new fridge and washing machine. The Electrolux fridge was the most energy efficient one that I could find at the time, with an estimated usage of 349kWh/yr it is probably our largest electricity consumer in the house. Our Bosch washing machine was also selected with energy/water efficiency and longevity in mind. When picking lighting for the house I was on a mission not to include any dreaded halogen down lights in our home, a lot of houses that I’ve seen have over 30, 50W down lights installed, which as well as being inefficient, often comes with the added handicap of having square meters of uninsulated ceiling area for heat to escape. We went with good old baton holders and to begin with we opted for compact florescent lamps (CFL) for most of the fittings, however we did also install a few LED lights in the kitchen and bathrooms, which on the most part have been great, although one of them gives off a slightly yellow light. My aim would be to replace these all with LED’s as time goes on, recent technology improvements and price decreases have made this a much more viable option.

Edible Garden

The garden and landscaping has been a constant work in progress for us, sometimes I wish that we had just borrowed some extra money and finished it off to begin with. Before moving into this house I’d had limited experience and success with growing my own food, but food can be a large part of our environmental footprint that we leave on the planet and local food production, I believe, is an important part of the puzzle. We started out with four vege boxes which we rotate with different vegetables across the seasons. Although there have been times when our vege boxes have been neglected, we have had some wins. Tomatoes, strawberries, broad beans, snow peas, spring onions, potatoes, basil, parsley, kale, leeks, mint, oregano, rosemary, corn, chives, cucumbers, chillies, capsicum, eggplant, carrots, beetroot, spinach, lettuce, broccoli and pak-choy have all had a run in our vege boxes, some with more luck than others. An honorable mention goes to the zucchini plague of 2012, where we were inundated with zucchini’s for weeks on end, we couldn’t eat them quick enough or give them away fast enough, by the end of it Holly was sick of cooking them and wrote a great blog post called zucchinis 7 ways in 7 days, on some of the recipes we used.

Zucchini Plague

Along with the vege boxes, we’ve planted a few fruit trees, we had about 100 Gala apples off our dwarf apple tree this year and our lots o’ lemons tree is currently living up to its name, the lime and nectarine tree have been more reserved in their offerings and more recently I’ve purchased a blood orange, lemonade and mandarin, which upon writing are yet to go in the ground.

As far as dealing with food waste, we have got two worm farms going that eat up most of our vegetable scraps, turning them into rich usable compost for the garden. We’ve also experimented with a Bokashi bin, which allows you to include meat scraps for composting as well, but this is currently not in rotation due to us running out of the sprinkly stuff you put in it to help the bacteria “pickle” the contents. We have also installed a 5000 Litre water tank which helps us water the garden as well as supplying water for the toilet and laundry.

As I mentioned at the start there a few things that we would probably do differently next time and a number of things on the to-do list. Grey water is an area we have yet to delve into, chickens will still require a bit of convincing for my wife (although I think I’m nearly there). Wooden window and door frames next time, instead of aluminium due to the high conductivity of the aluminium, the double glazing is doing its job, but is being partly undermined by the heat let into the house through the frames in Summer, more LED lighting and more time in the garden are also on the list. One major thing that I feel was a mistake and I would change if I had my time again is the gas, I’m saying this because I’d like others to consider this when building. The heating itself and the costs are great, but on a larger level the idea that gas should be used as a transition fuel I think is flawed. I agree with Beyond Zero Emissions argument that we need to make a rapid move towards a renewable energy and energy efficient future by electrifying our buildings, and instead of wasting money on gas that will need to be transitioned away from at some time in the near future, we should be spending this on moving towards renewable energy sources to start with. If I had the choice I would put an energy efficient reverse cycle air conditioner in, to be used solely for heating.

I guess that covers a large part of what we’ve been trying to do around the house to live a more thoughtful and environmentally conscious life. The benefits have been great, reduced costs on our electricity, gas, water and food bills and an insight into living a less wasteful life a little closer to nature. Come along on Sustainable House Day, Sunday September 8th 2013 to check it out, the Surf Coast Energy Group and Geelong Sustainability Group have houses open across the greater Geelong region.


Aaron Lewtas


Green Energy Options

Solar Panels and Shade

Shading can have a big effect on the performance of your solar power system. The amount of shading and the time of day may determine whether it is worthwhile putting solar panels on at all. Small amounts of shading at the start and end of the day may have minimal effects on output due to the losses being imposed on a reduced initial output. Ideally you want to have clear access to sunlight during the middle of the day between 9am to 5pm. Clouds will reduce the output of your solar system, but the panels will still receive dispersed light, its direct shading from trees, vent pipes and other objects that are of most concern.

Below is an example of electricity flow in a solar panel affected by shading.

The best way to assess the impact of solar on your rooftop is to have a shade analysis done. Green Energy Options use a SunEye to assess the impact of shade on your rooftop. The SunEye is a professional tool that takes a photograph of the surrounding objects through a fish eye lens, it then lays a sun path chart across the image showing the time of day and time of year that shading affects the location being assessed. The impact of shading for each month of the year is then calculated. We include the shading report in our estimates on your solar system’s output giving you an indication on how we expect your system to perform. Generally once you get above 10-20% of shading you need to consider if the solar system is going to have the effect that you intended, our aim is to put you in a position where you can make an informed decision.


SunEye Shade analysis

SunEye Shade analysis

It is important to be aware that in a standard solar system with a string inverter and 10 panels, shading on one panel can have a “weakest link” effect on the rest of the array, reducing the output of the whole string of 10. One option for reducing the impact of shading is to use micro-inverters. Micro-inverters individually optimise the output of each solar panel, so that shading on one panel doesn’t affect the output of its neighbors.


Shading micro-inverter vs string inverter

Shading micro-inverter vs string inverter

Image courtesy of Greenstar Micro-inverters

Green Energy Options can provide a detailed shade analysis of your site as well as options for both string and micro inverters. Give us a call to find out how you can go solar 1300 931 929.