Off-grid solar packages with batteries are built around one hard rule: when the sun is weak, there is no grid to catch you. That changes how you size everything, from the battery bank to the generator, and it is why a shed, a farm and a remote build need different answers.
If you are weighing up solar and battery systems for Adelaide and Sydney properties, this guide shows how to size an off-grid package from your real daily load, what a generator does, what it can cost and how the battery rebate treats off-grid sites.
Key takeaways
- Off-grid systems are sized from your real daily energy use and the days of autonomy you want, not from a power bill.
- Three days of battery storage is the common Australian design target, according to PSC Energy.
- A generator is optional, but without one the battery is your only backup in a long cloudy spell.
- Energy Matters estimates complete 2026 off-grid systems from about $18,000 to $85,000, depending on size.
- Clean Energy Regulator guidance says the battery rebate can apply to a lived-in off-grid dwelling, but not to sheds or bore pumps.
What are off-grid solar packages with batteries?
An off-grid solar package with batteries is a stand-alone power system: solar panels, a battery bank, an inverter charger and usually a backup generator, designed to power a property with no grid connection. It is sized around your real daily energy use and the days of autonomy you want, not your electricity bill.
How much battery does an off-grid system need?
Stand Alone Power Systems sets out the sizing order: work out daily energy use, decide how long the property must run without useful solar, size the array to cover daytime loads and recharge the battery, then size the inverter charger to peak demand rather than to the array.
PSC Energy gives a simple rule. Multiply average daily kWh by three days of autonomy, then add a 10 to 20% buffer. Its example is a 20 kWh a day home: 60 kWh baseline, or about 66 to 72 kWh with the buffer. PSC also notes that a 10 kWh lithium battery may deliver only about 8 kWh usable, so nominal capacity needs to be higher again.
Battery pack builder: one block is one day without sun
Method: daily kWh x days x (1 + buffer), then divided by the usable share. Based on PSC Energy sizing guidance. Illustrative only, not a quote.
Heavy loads move the numbers quickly. PSC says electric hot water can use 3 to 4 kWh a day, and a 2.5 kW split system running four hours uses 10 kWh. A real load audit, with future loads included, matters more than any rule of thumb.
Sheds, farms and remote builds: what changes?
The same components, very different priorities. Stand Alone Power Systems warns that the inverter must handle simultaneous appliances and pump or compressor start-up surges, so peak load often decides the size, not the daily total.
Pick your site type
Shed or workshop
- Small, steady loads plus occasional motor surges from compressors or tools.
- Size the inverter for the biggest tool starting while everything else runs.
- Rebate check: the Clean Energy Regulator says sheds are not eligible for the battery rebate.
Farm
- Pumps and cold storage create the peaks. Ask for a peak and surge assessment.
- A generator is common as a fallback for long poor-weather stretches.
- Rebate check: a lived-in farmhouse can be eligible, a bore pump cannot.
Remote build or cabin
- Plan for future loads now: extra sheds, pumps, air conditioning, a granny flat or EV charging.
- Choose your autonomy days and generator before the design, not after.
- Rebate check: the dwelling must be lived in, and each lived-in structure needs its own solar system.
Sources: Stand Alone Power Systems sizing guidance and Clean Energy Regulator battery eligibility page.
Do you need a generator with off-grid solar?
PSC Energy says a generator is optional, but without one the batteries are your only backup. When a generator is installed, the controller starts it at a preset battery level, typically between 20 and 30% capacity, recharges the batteries and shuts it off again. PSC puts a quality installed generator at about $3,000 to $8,000, and says most residential systems use 5 to 15 kVA units.
PSC describes three days as typical for a bad-weather stretch in most of NSW. Longer runs of four to six days need much more battery without a generator.
Six-day weather run: does the power stay on?
Illustrative model only, not a forecast: sunny days make 150% of daily use, cloudy 60%, rainy 25%. Generator start level follows the 20 to 30% range quoted by PSC Energy.
How much do off-grid solar packages with batteries cost?
Energy Matters publishes 2026 estimates by system size, and says off-grid systems are generally more expensive than grid-tied ones. It also warns that its own figures vary by circumstance and region, so treat these as a rough guide, not a quote. Battery type, installation, location and the autonomy you choose all move the price.
Estimated 2026 off-grid system price ranges
$0$20k$40k$60k$80k
$18k to $30k3 kW + 8 to 10 kWh
Small cabin
Small cabin
$35k to $42k6 kW + 20 kWh
3 bedroom home
3 bedroom home
$45k to $58k10 kW + 30 kWh
Large home
Large home
$70k to $85k15 kW + 50 kWh
Farm or large home
Farm or large home
Source: Energy Matters, Off-Grid Solar System Cost in Australia 2026. Estimates only. Bar heights are drawn to the stated ranges.
| Question | Grid-connected battery | Off-grid package |
|---|---|---|
| What if the sun is weak? | The grid tops up your supply | Battery, then generator, then power stops |
| What sets the size? | Bill, tariff and goals | Real load, peak demand and autonomy days |
| Generator? | Not needed | Common as a fallback |
| Best fit | Homes with a reliable connection | Sites where connecting is costly or impractical |
If you already have the grid at the boundary, a connected battery is often the simpler comparison. Our guides to residential energy storage systems and commercial solar battery systems cover that route.
Can off-grid solar packages with batteries get the battery rebate?
Sometimes. The Clean Energy Regulator says off-grid systems are eligible when the battery serves a dwelling that is lived in, such as a remote farmhouse. Structures that are not lived in, such as sheds or bore pumps, are not eligible. It allows one battery per off-grid dwelling, and each extra lived-in structure needs its own solar system to claim.
The battery must be installed with a solar PV system. If the property is more than 1 km from the grid, it does not need to be capable of joining a virtual power plant. Within 1 km it must be, unless you hold written evidence that connecting would cost more than $30,000. Rules change, so check your 2026 battery rebate eligibility before you sign.
Rebate pathway check for off-grid sites
Source: Clean Energy Regulator, solar batteries guidance. A guide only, not an eligibility decision. Confirm with your installer.
Standards, accreditation and six questions to ask
Several Australian standards apply to solar and stand-alone installs, including AS/NZS 5033 for PV arrays, AS/NZS 4509 for stand-alone power systems and AS/NZS 5139 for batteries, as listed by the Australian Government business portal. Ask your installer which parts apply to your site.
- What daily kWh and peak kW did you design for?
- How many days of autonomy does the battery cover?
- What is the usable capacity, not just the nominal figure?
- Is a generator included, and at what charge level does it start?
- Which future loads (pumps, sheds, EV charging) were allowed for?
- Which battery model is on the Clean Energy Council approved list, and is the site eligible for the rebate?
When off-grid is not the right move
If a grid connection is already at your boundary and affordable, off-grid may cost more for less certainty. It can also disappoint if loads are large and unplanned. Start with a load audit. Our guide to residential battery storage specifications explains the capacity, power and warranty terms behind any quote.
Frequently asked questions
What size battery do I need for an off-grid solar system?
Start with your daily kWh use, multiply by three days of autonomy and add a 10 to 20% buffer. PSC Energy’s example is 20 kWh a day, giving 60 kWh baseline or about 66 to 72 kWh with the buffer. Usable capacity is lower than the label, so ask for the nominal figure too.
Do I need a generator with off-grid solar?
It is optional, but without one the batteries are your only backup. PSC Energy says a generator typically starts when the battery falls to 20 to 30% capacity, recharges it and shuts off. It puts a quality installed unit at about $3,000 to $8,000. Long cloudy spells are the main reason people add one.
How many days of battery storage does an off-grid system need?
Two to three days is the usual target. HighFlow Energy describes 2 to 3 days of stored energy for resilience, and PSC Energy calls three days the Australian standard. Without a generator, PSC suggests four to six days, which needs much more battery. The right figure depends on your location and risk tolerance.
How much does an off-grid solar system cost in Australia?
Energy Matters estimates 2026 prices from about $18,000 to $30,000 for 3 kW of solar with 8 to 10 kWh of battery, up to $70,000 to $85,000 for 15 kW with 50 kWh. These are estimates that vary by site, so get a written quote based on your load audit.
Can I claim the battery rebate for an off-grid shed?
Not for the shed itself. The Clean Energy Regulator says sheds and bore pumps are not eligible, while a battery for a lived-in off-grid dwelling can be. Each lived-in structure needs its own solar system to claim. Check your 2026 battery rebate eligibility with your installer before buying.
Is off-grid solar more expensive than a grid connection?
Energy Matters says off-grid systems are generally more expensive than grid-tied ones, but suit properties where a connection is costly or impractical. Ask your network for a written connection quote and compare it with a full off-grid price, including the generator and future loads, before deciding.
Plan your off-grid package around your real load
The right package starts with a load audit, not a catalogue. UR Local Solar reviews your electricity usage, roof, goals and budget before recommending a system, with service teams in Adelaide and Sydney. See our solar battery systems overview, and ask about your property’s location.
Ready to talk through your site? Book an appointment and bring your appliance list.
Sources
- PSC Energy: How much solar and battery for off-grid solar?
- PSC Energy: Do you need a generator with off-grid solar?
- Energy Matters: Off-Grid Solar System Cost in Australia 2026
- Clean Energy Regulator: Solar batteries
- Stand Alone Power Systems: What size off-grid solar system do I need?
- HighFlow Energy: Off Grid Power in Australia
- Australian Government business portal: Solar (photovoltaic) systems standards
