Home batteries

If you already have solar panels, you may need to upgrade your system to add a battery. You might need to upgrade to a hybrid inverter or add a second, battery-dedicated inverter. Some batteries come with everything built in.

Adding a battery to an existing solar system is usually a simple process, but you should talk to your installer about what upgrades are needed.

If you're installing solar now and plan to add a battery later, ask your installer to make your system battery ready.

The best battery size for your home depends on:

• how much energy you use
• when you use it
• the size of your solar system
• any future upgrades you might want, like switching from gas hot water to an electric heat pump, or adding more solar panels.

Battery capacity is how much energy a battery can hold, measured in kilowatt-hours (kWh). Most home batteries store between 4 and 14 kWh, while bigger commercial ones can hold over 100 kWh

A 6kWh battery suits 90% of households, according to an audit of 9,500 homes by the Smart Energy Council.

With a 6kWh battery, a household could:

• Power an average-sized fridge for 40 hours.
• Do a full load of laundry (wash + dry) and still have 2.5 kWh left for other things like lighting or charging devices.
• Run a split-system air conditioner for 5 hours, keeping the house cool in summer or warm in winter without drawing from the grid.

Choosing the right battery size is important to get the most value from your system. If the battery is too big, it costs more and takes longer to pay off. If it's too small, you’ll need to buy more power from the grid. A battery that’s used too little or too much can also lose efficiency and wear out faster.

Batteries are safe when installed and used properly. Just like any electrical device, they should be installed by a professional and checked regularly.

Batteries must be:

• Installed by a licensed electrician who is also an accredited battery installer under Solar Accreditation Australia.
• Listed on the Clean Energy Council approved product list.
• Certified with a Certificate of Electrical Compliance after installation. This certification is essential for both safety and insurance purposes.

Batteries store electrical energy in chemical form and release it as needed. There are four main battery types, with Lithium-ion being the most common:

• Lithium-ion batteries are the most common and practical choice for home solar storage today due to their reliability and falling costs. They dominate the market and are expected to remain the top option for years to come.
• Lead-acid batteries are older, bulky, and need more maintenance. While cheaper upfront, they wear out faster and end up costing more over time, making them less suitable for modern on-grid homes.
• Flow Batteries use liquid electrolytes and offer good fire safety, but the only residential option is no longer available. They’re unlikely to return to the home market anytime soon.
• Sodium-ion batteries are a promising new alternative to lithium, using cheaper materials and offering similar performance. However, they’re not yet available for home use and may take years to become a viable option.

Most batteries come with a monitoring app or portal. These tools let you track:

• Charge level
• Energy usage
• Solar input
• Battery health

You can usually access this data via your smartphone or computer.

When your battery is fully charged, any additional solar energy is typically:

• Exported to the grid (if your system is grid-connected)
• Wasted (if off-grid and no load is drawing power).

Some systems allow you to divert excess energy to appliances like water heaters.

It depends on your system. Not all batteries provide backup power. To work during a blackout, your system must include:

• A hybrid inverter or backup gateway
• A battery with backup capability

Check with your installer to confirm your setup. This includes understanding how the battery will be installed and if it will provide power only to essential loads like lights, or essential and non-essential loads, like an oven or dishwasher.

Most batteries last:

• 10–15 years on average
• 4,000–6,000 cycles (the charge and discharge of a battery) depending on usage and quality

Performance may decline gradually over time, but warranties often cover 70–80% capacity after 10 years. Talk to your installer and equipment supplier about battery life and performance guarantee.

Some batteries may need to be installed in a covered area or have an awning to protect them from extreme weather conditions. Speak to your installer about what level of protection your chosen battery will need.

No, you don’t need a battery to use solar panels. Without a battery:

• You use solar power during the day
• Excess energy is sent to the grid
• You use power from the grid when the sun is not shining, like on cloudy days or at night.

Adding a battery gives you more energy independence and backup power.

Charging time depends on:

• Battery size (capacity in kWh)
• Solar panel output
• Weather conditions

On average, a home battery can fully charge in 4–8 hours of good sunlight.

Most systems can be retrofitted with a battery. You should consult a solar professional to assess your system’s compatibility.

You may need:

• A compatible inverter or a separate battery inverter
• Space for installation
• Electrical upgrades in some cases