An off-grid home isn't connected to the electricity grid. It makes its own power, usually from solar with battery storage, collects and treats its own water, and deals with its own sewage on site. Done well, it means no power bills and real independence. Done badly, it means cold showers and a generator running all night.

The secret is that an off-grid home starts with the design, not the solar panels. Every kilowatt-hour you don't need is one you don't have to generate and store.

First, run the numbers

Before you commit, compare:

  • The cost of connecting to the grid. On a block near the power lines, connection can be cheap. On a remote rural block, it can run to tens of thousands of dollars, which is often what makes off-grid worth it.
  • The full cost of an off-grid system: solar panels, batteries, inverter, backup generator, and replacing the batteries every so often over the life of the house.
  • Council approvals, especially for on-site sewage.
  • Bushfire requirements on rural blocks. A bushfire attack level (BAL) assessment to AS 3959 can affect materials, windows and costs, and you'll want water set aside for firefighting.

Passive design does the heavy lifting

Passive design means designing the house to stay comfortable with little or no heating and cooling.

  • Face the main living areas north to make the most of winter sun and natural light. Size the eaves so they shade the windows from high summer sun and let low winter sun in.
  • Insulate and seal well. Insulation in the roof, walls and floor, and an airtight building envelope, reduce heat gain in summer and loss in winter.
  • Use thermal mass wisely. Concrete slabs, masonry or rammed earth store heat and smooth out temperature swings, but only where they get winter sun and summer shade.
  • Design for cross ventilation. Place windows on opposite sides of rooms to catch prevailing breezes. In much of Queensland, good airflow and shading matter more than heating.
  • Keep it compact. A smaller, well-planned home needs less energy to run and less money to build.
  • Choose good glazing, and limit west-facing windows.
sunlight shines on the wall through the window with open Venetian blind
Photo by Ruan Richard Rodrigues / Unsplash
bricks as a building material to make houses
Photo by Mufid Majnun / Unsplash
Tiny home with kitchen desk and dinning
Photo by Jed Owen / Unsplash

Power

Solar panels

Solar is the main power source for most off-grid homes in Australia. Panels need a clear, unshaded roof or ground mount. North-facing gives the most energy across the day, though east and west arrays can help spread generation through the morning and afternoon.

Solar and battery systems must be designed and installed by an accredited solar installer and a licensed electrician. Off-grid systems are designed to AS/NZS 4509 (stand-alone power systems), with solar arrays to AS/NZS 5033. This isn't a DIY job.

Batteries and inverters

Batteries aren't optional off-grid. You need battery storage sized to carry your home through several cloudy days, plus an inverter big enough for your peak loads (think kettle, oven and pump running at once). Most off-grid homes also have a backup generator for long stretches of bad weather.

Your installer will size the system from your expected energy use, so be honest about it. An induction cooktop, a heat pump hot water system and efficient appliances make the whole system smaller and cheaper.

Wind

Small wind turbines can help in consistently windy locations, and a combination of solar and wind can even out supply. For most sites, though, solar with batteries and a generator is simpler and more reliable.

water tank tower placed on barren ground during daytime
Photo by Casey Schackow on Unsplash

Water supply

Off-grid, rainwater is usually your water supply.

  • Tanks: size them for your household's use and the dry season, not just the average month. Talk to your local council about what's typical.
  • First flush diverters and screens keep leaves and roof grime out of the tank.
  • Filtration and treatment if you'll drink the water. Get it tested.
  • A pressure pump supplies water from the tank to your taps. Plan for its power use, or add a small header tank or backup.
  • Fire fighting: on bushfire-prone blocks, a dedicated firefighting water supply may be required.
Blue tank
Image source 04Julie1967

Wastewater

Without a sewer connection, you need an on-site sewage system. In Queensland, on-site sewage systems need council plumbing approval and are designed to AS/NZS 1547. Your soil type and block size will decide what's possible, so get a site and soil evaluation early.

  • Septic tanks with a land application area (trenches or beds) are still very common.
  • Aerated wastewater treatment systems treat sewage to a higher standard for irrigation. They use power and need regular servicing.
  • Composting toilets reduce water use but still need approval and proper management, and you'll still need a system for the rest of your wastewater.
  • Greywater (from showers, basins and laundry, not toilets) can be reused for garden irrigation with an approved system.

How to get started

  1. Check the block: sun, shade, slope, soil, access, bushfire rating and how far it is from the grid.
  2. Talk to council early about building approval, on-site sewage and any planning rules.
  3. Set a realistic budget that includes the power, water and sewage systems, not just the house.
  4. Engage designers and builders with off-grid and passive design experience.
  5. Get your energy system designed by an accredited solar designer based on your actual house design and appliances.
  6. Plan for maintenance: batteries, pumps, filters and treatment systems all need regular attention.

Be ready to be your own utility

Off-grid living means managing your own power, water and waste. You'll learn to watch the battery level on a run of grey days and to keep up with servicing. For a lot of people that's the appeal. Just go in with your eyes open, and design the house first.

Further reading

Mastering Energy Efficiency: Air Sealing & Insulation TipsBuilding an energy-efficient home is more than just a trend; it’s a responsibility. Dive into the intricacies of air sealing, insulation, and the importance of thermal mass. Discover how these elements can drastically reduce energy consumption and promote sustainability.NatHERS star scale: more stars means less heating and cooling, with 7 stars the NCC 2022 minimum for most new homesDecoding Home Energy Star Ratings: What Homeowners Should KnowUnderstanding the energy efficiency of your home is crucial. The NatHERS star rating, ranging from 0-10 stars, evaluates the thermal comfort of a house. A higher rating indicates better energy efficiency, potentially reducing the need for artificial heating or cooling.Section through a double-glazed window showing two panes, the sealed gap, spacer and edge seal, keeping summer heat out and winter heat inGlazing for Your Home: Comfort, Energy, and Cost InsightsGlazing greatly impacts your home’s comfort, energy efficiency, and costs. Understanding glass types, frame materials, and installation can help you optimise thermal performance, lower energy expenses, and improve sustainability in your new home.Optimizing the 4 Control Layers for High-Performance HomesBuilding an energy-efficient home requires a good understanding of the four control layers: water, air, vapour, and thermal. In this post we look into how project builders can optimise these layers, ensuring homes are comfortable, sustainable, and cost-effective.