Capacity option
16 kWh usable
Cover a smaller energy gap
A starting point when measured evening and overnight demand fits within this amount, allowing for conversion losses and your chosen backup reserve.
Home solar battery sizing • Understand the capacity
16kWh vs 24kWh vs 32kWh solar battery: which size fits?
Compare what different amounts of storage can do for your home. Start with usable energy, then check charging power, backup capability and room to expand across the battery systems on your shortlist.
Compare stored energy first
For this guide, 16kWh, 24kWh and 32kWh mean usable battery capacity. Actual products may use nearby sizes or advertise nominal capacity instead. Check the manufacturer’s usable-energy figure before putting two systems side by side.
Capacity option
24 kWh usable
Carry more into the evening
50% more storage than 16kWh. Worth assessing when the smaller battery would regularly leave a shortfall and your charging plan can refill the extra capacity.
Capacity option
32 kWh usable
Plan for larger energy needs
Twice the storage of 16kWh. Consider measured demand, future loads and an agreed backup reserve alongside the energy available to recharge it.
Storage is only one part of the system. A 32kWh battery with a 5kW inverter and a 32kWh battery with a 10kW inverter hold a similar amount of energy but can support different simultaneous loads. Battery discharge limits and the backup design also matter.
Use the right part of your electricity bill
A home using 30kWh a day does not automatically need a 30kWh battery. Some electricity may be used while the panels are generating. The useful starting point is the energy you want to shift into the evening, overnight or another expensive period.
- Measure the gap: review smart-meter interval data or solar monitoring to see when imports occur.
- Check charging energy: compare surplus solar across seasons. Planned grid charging needs a suitable tariff and operating strategy.
- Allow for reserve and losses: energy held for outages is unavailable for routine use while it remains reserved.
- Consider future loads: an EV, heat-pump hot water or longer air-conditioning hours may change demand. Daytime scheduling can reduce the storage needed.
A bill can begin the discussion; interval data makes the recommendation more specific.
What does an extra 8kWh change?
Suppose a household wants to cover 18kWh between the end of solar generation and the next morning. Assume each battery starts full and retains a 20% backup reserve. This is an illustration, not a particular brand’s operating prediction.
| Usable battery size | 20% held in reserve | Remaining before losses | Against an 18kWh target |
|---|---|---|---|
| 16kWh | 3.2kWh | 12.8kWh | At least 5.2kWh short |
| 24kWh | 4.8kWh | 19.2kWh | Only 1.2kWh margin before losses |
| 32kWh | 6.4kWh | 25.6kWh | 7.6kWh margin before losses |
The 24kWh option is close in this example: losses and actual consumption could still leave a shortfall. The 32kWh option gives more energy headroom, but only if it charges sufficiently. A 20% reserve is an illustrative choice, not a universal recommendation.
Check the charging side too. If the household normally has only 12kWh of surplus solar, buying a larger battery does not create the extra energy needed to fill it. Review actual generation, household use and any planned grid charging.
Choose a platform that can grow with the home
After estimating useful capacity, compare what each system can become. The battery installed today may be only part of the platform’s capability.
Storage expansion
Check the largest supported stack, the number of stacks and whether the existing inverter supports that configuration. “Expandable” does not mean every battery module can be added to every inverter.
Power and supply phase
Compare inverter options, battery-only discharge power and the limits on each phase. A three-phase appliance needs an appropriate backup design, not just a large kWh figure.
Cold-weather operation
Ask whether the exact battery version has a heater, how it is powered and whether heating works during an outage. Low-temperature discharge capability does not guarantee charging at the same temperature.
Installation space
Allow for the complete future configuration, required clearances and protection from the local environment. Check indoor/outdoor suitability and shelter requirements in the installation manual.
Compare home solar battery capabilities, heaters and installation suitability across FoxESS, Sungrow, GoodWe, Sigenergy and other systems.
Compare installed value at the size you need
Ask each supplier to quote a configuration near your target usable capacity with the same backup requirements. Include the inverter if needed, metering, mounting, commissioning, switchboard work and site extras. Check GST and whether an incentive has already been deducted.
A larger battery is not automatically better value. Compare the extra installed cost with how often the additional capacity would be charged and used, then consider the backup or future-expansion benefit you want from it.
Battery sizing questions
Is a 16kWh battery enough for my home?
It may be. The answer depends on when you use electricity, charging energy, operating losses and the energy reserved for outages. Household size alone is not a reliable sizing method.
Will a 32kWh battery run my home for a full day?
There is no fixed runtime. Divide the energy available after reserve and losses by the average load for an initial estimate, then check changing loads and power limits. Essential-circuit backup and whole-home operation are different requirements.
Does 32kWh mean 32kW of power?
No. kWh measures stored energy; kW measures power at a particular moment. The inverter, battery module count, temperature and system settings determine how much power is available.
Can I add battery modules later?
Expansion is model-specific. Confirm supported module generations, timing restrictions, firmware requirements, physical space and the inverter’s capacity limits before relying on an upgrade.
What if my home has three-phase power?
Check both normal operation and blackout operation across the phases. Send your supply and existing inverter details so an appropriate design can be assessed, particularly if you want to back up three-phase equipment.
Match the system to your household
Send a recent electricity bill, your inverter model, your suburb and your backup priorities. We can compare suitable sizes and the expansion potential of the platforms you are considering.
Sources and assumptions
Reviewed 13 September 2026. The capacity options and reserve calculation are generic illustrations, not retail package specifications or a site simulation. General background: Australian Government solar and battery sizing guide. Model-specific sources are linked in our battery platform comparison.