Fast read
Battery storage needs vary based on your household size, energy usage, and goals. For a small household (1–2 people, using 8–12 kWh/day), a 3–7 kWh battery can often cover most evening use. An average household (3–4 people, 16–22 kWh/day) usually benefits from a 7–13 kWh system to maximise solar self-consumption and provide partial backup.
Large households (5+ people or energy-intensive lifestyles) often require 13 kWh or more, especially if aiming for greater independence or whole-home backup. These are general guidelines—getting a professional assessment is key to making the right investment.
How much battery storage is enough for a small, average, and big household?
Before choosing a battery, it’s crucial to understand how much energy your home uses each day, measured in kilowatt-hours (kWh). You’ll find this on your power bill or through your smart meter data.
Here’s a guide to average daily electricity use across Australia:
- Small household (1–2 people): 8–12 kWh/day
- Average household (3–4 people): 16–22 kWh/day
- Large household (5+ people or high-usage homes): 25 kWh/day or more
Usage patterns vary widely depending on your climate, the efficiency of your appliances, heating and cooling habits, and lifestyle factors like working from home or owning an EV.
What do you want your battery to do?
Your goals for installing a battery will directly shape what size you need. Common reasons include:
- Maximising solar self-consumption – storing daytime solar for evening use
- Blackout protection – keeping essentials like fridges and lights running during outages
- Reducing energy bills – avoiding peak electricity rates
- Boosting energy independence – relying less on the grid
- Joining a Virtual Power Plant (VPP) – some retailers offer credits for letting your battery help stabilise the grid
If you’re mostly interested in evening use coverage, a smaller battery may be sufficient. But if you’re after full-home backup or aiming to be nearly off-grid, you’ll need more capacity and power.
Key factors that influence battery size
Choosing the right size battery isn’t just about your daily usage. Consider these critical variables:
Your solar system’s size
A battery needs enough excess solar energy to charge. If your solar system is too small, a large battery may stay half-full. As a rule of thumb, a battery capacity 1.5 times your system’s size (in kW) is often recommended. For example, an 8 kW solar system pairs well with a 12 kWh battery.
When you use electricity
If your peak consumption is after sunset—common in most homes—a battery can be highly effective. Smart monitoring of your load profile helps match battery size to when energy is needed most.
Backup needs
Do you just want to back up a few essentials (fridge, lights, Wi-Fi) or the whole house? Full-home backup typically requires more capacity and a higher power rating, which also affects inverter choice and installation complexity.
Battery specs: capacity vs. power
- Usable capacity (kWh): This is the actual energy you can draw, often 90–95% of the total capacity due to discharge limits that protect battery lifespan.
- Power rating (kW): This determines how many appliances the battery can run at once. A large capacity battery with low power output might not meet high short-term demands (like kettles or air cons turning on simultaneously).
Budget and expandability
Battery systems aren’t cheap. Many are modular (e.g., Sungrow’s modular range or Tesla Powerwall-compatible add-ons), so starting small and expanding later is a smart path for some households.
Typical battery sizes by household type
Small household (1–2 people, 8–12 kWh/day)
Recommended size: 3–7 kWh
A smaller battery can handle most evening consumption and give you limited blackout protection for key appliances. Compact units like the sonnenBatterie Evo (5–10 kWh) or the modular Sungrow SBR series (starting from 3.2 kWh) are popular options.
Average household (3–4 people, 16–22 kWh/day)
Recommended size: 7–13 kWh
This size range suits families who want to make full use of their solar system and reduce grid dependence. Many Australian homes install batteries around 10 kWh. Popular models include the Tesla Powerwall (13.5 kWh) and the LG RESU Prime (10–16 kWh). For most, a 10 kWh battery will comfortably cover night-time usage on typical days.
Large household (5+ people or high users, 25+ kWh/day)
Recommended size: 13–20+ kWh
If your home has high energy needs—think ducted air con, pools, electric vehicles—larger battery systems are more suitable. Some households install multiple units or modular systems reaching 20 kWh or more, especially if seeking whole-home backup or significant autonomy.
Note: The average home battery installed in Australia in 2023 was about 11.3 kWh. Modular designs let you expand as needs grow.
Why one-size-fits-all doesn’t work
A common trap is either under- or over-sizing. Oversizing increases your upfront cost without necessarily improving your return on investment. Undersizing might leave you frustrated when your battery can’t deliver during long outages or cover your evening use.
As a rule of thumb, you might start with:
25% of your daily usage + 2 kWh buffer
For example, if your home uses 20 kWh daily:
→ 20 x 0.25 + 2 = 7 kWh battery (minimum for meaningful impact)
But remember: this doesn’t consider when that usage occurs or how much solar you have. Tailored design is critical.
The best next step: Get a professional assessment
The most reliable way to right-size your battery is to work with a Clean Energy Council (CEC) accredited installer. A detailed energy assessment will:
- Analyse your energy usage patterns
- Understand your goals (e.g., backup, bill savings, VPP participation)
- Evaluate your solar system’s production
- Factor in shading, roof space, and your budget
This ensures your battery performs as expected and delivers long-term value.
Your Energy Answers can connect you with trusted, accredited solar and battery experts in your area —at no cost. Get the clarity you need to invest confidently and build a more resilient, energy-smart home.
