Harmony House





It's a great feeling knowing that every single watt of power our household uses comes from the sun. Off-grid power doesn't suit every situation of course, so some good decision-making goes a long way in avoiding any expensive mistakes. Read further through this page for more information on our aims, research, decisions and results, as well as our tips and advice summary, for this element of our project - our off-grid energy system.


One of the main aims with our build was to be as sustainable as possible, so an off-grid solar PV system was always what we had in mind. We understood from the outset that the upfront cost would be significant, and in all likelihood wouldn’t pay itself back for a decade. However the opportunity to set ourselves up in this way while doing a new build offered some financial efficiency (for example, by designing our building structures and heating and cooling systems around our intended aim), and in the end we'd be financially better off after the recoup period.


Early in my research I came across a case study article that interviewed a range of households living with an off-grid solar PV system. It seemed that the households fell into two main groups: those that were living happily and comfortably with their system (they generally had a system designed by experienced professionals), and those that struggled somewhat with power outages etc (they generally had less experienced designers and installers). So from that point my research focused on finding the best designer and installer I could.

To aid my search I first read up on off-grid solar PV system design to increase my understanding as much as possible. That way when I phoned system installers I could ascertain what their level of knowledge and experience was. This proved a very useful strategy, as I found that many installers come from a background of being an electrician and moving into solar PV installation, often with most of their experience being with grid connected systems or hybrid systems (grid connected with a battery bank). In the end there was one company that stood out by a huge country mile as being genuine experts in off-grid systems - they were Off-Grid Energy Australia. They showed extraordinary knowledge of off-grid system design, and exceeded my expectations in terms of design service and outcomes.


Once we’d identified Off-Grid Energy Australia as the best contractor for the job (on the basis of knowledge, expertise, experience and price), we were confident in leaving the technicalities of the system design to them (they go to great lengths to research the companies of each product they use to ensure quality and longevity of support). The main decision was really “how big” we wanted the system to be. The size of an off-grid system is obviously directly related to usage needs (the size of the family) and budget. We have two young children, so not a large family, but young children grow into older children, and we also wanted the possibility of charging an electric car during the summer months, so we stretched for as large a system as we could afford. Off-Grid Energy Australia were fantastic in helping us:

i) determine what our current energy uses were before the build (in a very inefficient rental that was cold in winter and hot in summer),

ii) estimate how those energy uses might alter living in the very efficient passive solar build we were planning, and

iii) explore different system options and capacities to see what fitted in with our budget and our hopes for the future.

The main components of the system we ended up with are:

48 x REC 290W Twin Peak polycrystalline solar panels (13.92 kWp)

1 x Selectronic SP PRO SPMC482-AU inverter/charger (7.5kW cont. delivery)

2 x Fronius Primo-6.0-1 (SCERT) solar inverter

1 x link kit and tablet display for 'Quick View' system monitoring

A professionally designed solar PV system is best for robust performance

Off-Grid Energy Australia have such experience in off-grid systems and confidence in their system designs that they can spec your system to be ‘generator free’ (i.e. back-up generator not required), which was an option we enthusiastically chose in our aim to have a fossil fuel-free household.


We had made our decision on the power system design ahead of the physical house build so that we could ensure that the drafted house plans included everything necessary to house the equipment (for example, battery room size, battery room ventilation, roof space for solar panels, connection pathway to the tablet display, etc). So from then it was really just a matter of waiting until the house build was at the right stage (roof on, among other things!), at which point Off-Grid Energy Australia arrived to do their thing. The installation went smoothly and efficiently, and within two days we had a fully functioning power system.


In a word, excited! We had a fully functioning, fully independent power system - it was like suddenly owning a mini power plant, but one that runs entirely on sun energy and which would provide our family environmentally friendly and sustainable power for decades to come. We couldn’t wait to move in and use it, but there were still a few months of the build left to last through!

Forty-eight solar panels provide us with ample energy


We quite honestly couldn’t be happier. It’s an extremely gratifying feeling knowing that every watt of energy we use has been generated from the sun.

We were aware going in that living with an off-grid energy system requires a certain amount of ‘user interaction’ and ‘usage commonsense’ (unless your budget is deep enough to negate the need for commonsense, which ours certainly wasn’t). However we have found this user interaction aspect has been minimal and very easy to do. It bascially involves making the best use of our system by choosing to do our discretionary loads during the day (things like the dishwasher, washing machine, vacuuming, any house heating or cooling if needed, clothes dryer, etc), using the directly available power through the AC-coupled solar panels rather than dipping into the battery bank overnight. In winter we can even choose the sunniest parts of the day to do our largest loads. That actually becomes part of the fun, being aware of the weather conditions outside and making usage choices based on that.

In fact, one of the best tips I can give to help that process along is to have your system data available in a really convenient and accessible position. We have a small tablet screen flush-mounted into a kitchen wall, so at a glance we can see exactly how much energy our  appliances are currently drawing, how much of that is coming directly from the panels, and how much might be coming from the battery bank. After a few months of watching that panel closely, and relating it to the clouds and sunlight I was seeing outside, I soon became really adept at knowing from a glance outside what loads to do when to get the most out of the system.

Having your system data easily accessible helps get the most out of your solar PV system

Perhaps one of the clearest indications we’ve had that we ‘got everything right’ (i.e. that we sized the system correctly for our family, and that our usage habits are working nicely with the system) is that the battery bank has almost never been below 80%, even during the middle of winter. This shows the system has good design redundancy, and gives us scope for a future electric vehicle if we can afford one down the track.

We are extremely grateful to Off-Grid Energy Australia for their knowledge and skill in the design and implementation of our system, as well as their patience and customer support along the way. It really has been a very successful outcome, and we love living off-grid. It really does feel good knowing that all our energy comes from sunlight - none from fossil fuels - and the fun little game of matching energy usage to sunshine and weather conditions has a great side-effect of making us feel more connected to, and aware of, the natural world around us.


     - Unless you have far above average skills in this area, get your system designed by a professional.

     - Educate yourself as much as possible on the subject, so that you can have informed conversations with potential contractors (i.e. be an informed customer, not an ignorant one).

     - Use your knowledge to shop around for a skilled and knowledgable contractor that you have confidence in.

     - Make sure either that your budget fits with your system desires, or that your system expectations fit with your budget.

     - Be aware going in that ‘user interaction’ and ‘usage commonsense’ is part of the deal.

     - Having your system data easily available in a really convenient place helps you learn about your system and get the most out of it.

     - Enjoy the fun and satisfaction of being more in tune with nature, and being more environmentally friendly as a result.