If you're considering heating, cooling and hot water solutions for your off-grid home, then you should look at non-gas solutions to avoid paying expensive running costs.
The main energy source options are solar power, wind power and firewood if it is freely available on your site. You will also likely need a diesel generator backup in extreme situations. The size of solar or wind power system will depend on the size and efficiency of your home and the power requirements of your appliances. With all things considered, you will likely be looking at 10kW or more of power from renewable sources.
You also need to consider battery storage and there are many battery systems on the market from Lithium Ion Phosphate types (eg smart phone batteries) to Lead Acid (eg standard car batteries) and Salt Water batteries (eg Aquion Energy, new to the market). Salt Water batteries are more expensive but safer, more robust and easier to maintain as they do not require cycling to maintain performance and life. They can also operate happily between -5°C to 40°C so ideal for tough Australian conditions, whereas the other batteries need a more temperate environment and fire suppressions systems in the event of thermal runaway problems. Also, Salt Water batteries can be disposed of safely without any special equipment or containers, whereas the other batteries need to be specially disposed of. If you would like to enquire about salt water batteries for your home, click here.
You may also consider grouping up 3 or more standard 315 litre storage tanks to store hot water produced during the day when the sun shines for use in a hydronic heating system at night. This is another form of battery because well insulated hot water storage tanks will store energy and typically lose only 5% (approximately) of their energy over a 24 period in shoulder seasons, less in summer and more in winter.
Passive heating design and energy recovery ventilation should also be considered to reduce your energy load in heating during the winter. In summer, you should have plenty of power for your energy requirements with a power system generating 10 kW or more but in winter when the sun is weak and the weather is cold, raining or cloudy, your heating needs will be greater and your solar power production will be less. This is the most difficult time of the year to keep an off-grid home operating comfortably. Adding a wind power to your system will help in the winger and if you have firewood freely available that will help also. You may wish to consider a wood fired stove in your kitchen. There are many models on the market.