Adding batteries or solar panels to an existing system

I plan to install a solar and battery system, or I am considering adding a battery within the next few years

Customers installing a new solar and battery system at the same time, or who are installing solar and plan to add a battery later, should speak to their installer about using a ‘hybrid inverter’.

Hybrid inverters are now often available at a similar cost to non-hybrid inverters and are sometimes called ‘battery ready inverters'.

Hybrid inverters are the most effective option for combined solar and battery systems and are the simplest option if you plan to add a battery to a solar-only system later.

From 1 May 2026, all new or upgraded systems come with a consumption monitor, which allows you to:   

• See how much electricity you are using and how much of that is from your own solar or battery system.

• Check whether your system is performing properly.

• See when your battery is charging or discharging.

I already have a solar system. What are my options to add more panels or a battery?

There are cost-effective options for customers with all solar system types to add more panels or a battery.

Adding or upgrading an inverter or battery

If you are adding a new inverter (including replacing your current inverter with a bigger one), all inverters at your premises will need to be able to communicate with each other as a single integrated system. The system must have visibility of all managed inverters and be able to control the power setpoint of each inverter for generation and export limits, without using binary on/off hard limits.

Installers may refer to this as ‘whole of site compliance'.

There are different ways to achieve whole of site compliance depending on the make and model of your inverter, and the type of your inverter:

• Hybrid inverter
• Non-hybrid inverter

Customers can add batteries to either inverter type, but compatibility and the installation process vary.

All inverters show a model number on an affixed electrical label, which you can usually check against the Clean Energy Council’s approved inverters list. Some older inverters may no longer be listed, and your installer will be able to confirm.

I have a hybrid inverter

In most cases, installers can easily add a compatible battery to an existing hybrid inverter using a ‘DC coupled’ battery. Your existing inverter will control the flow of electricity between your rooftop solar, battery, and home or business. Installers can advise which DC coupled batteries are compatible with your specific inverter, as these are often brand specific.

If you are adding a second inverter to an existing hybrid inverter, the information below on gateways and parent-child inverters also applies.

I have a non-hybrid inverter

In most cases, the simplest option to add a battery to a non-hybrid inverter will be using an ‘AC coupled’ battery. This option also applies for customers with ‘microinverter’ systems.

Achieving whole of site compliance for these upgrades can be achieved in some different ways.

Gateway option

Particularly for AC coupled batteries that are a different brand to your existing inverter, a gateway is likely the best option. Your existing inverter will continue to control electricity flow between your rooftop solar and premises. A separate battery inverter will control battery charging/discharging and is usually internal to the battery.

A small ‘gateway’ device is the brains of the site – it allows the inverters and batteries to talk to each other, so that different devices work together as a single integrated system.

Additional inverter in parent-child mode

Particularly for inverters installed before July 2025, system owners may be looking to install a battery and add more inverter capacity at the same time.

Instead of a gateway, it is possible to add a new hybrid inverter alongside your existing inverter. The new hybrid inverter will act similarly to a separate gateway and can control both inverters in what is called ‘parent-child mode’.   

Inverters in parent-child mode are usually from the same manufacturer, and this mode often offers both better functionality and lower retrofit costs. Not all manufacturers offer this feature.

Adding more solar panels (no other system changes)

When adding panels to an existing system, installers will often prefer to leave existing rows (or ‘strings’) of panels untouched and to add new strings alongside your existing panels. When this happens, each string is connected to your inverter separately. Speak to your installer about whether your inverter has enough ‘maximum power point trackers’ – or MPPTs – to accommodate extra panels. MPPTs make sure your panels generate as much electricity as possible.

Adding extra panels to an existing string or adding extra strings without any other changes to the inverter does not trigger whole of site compliance requirements for the system.

If your system does not have enough MPPTs, it may not be possible to add more panels, and you may need to add or replace an inverter to be able to add more panels. Generally, PV strings on each roof surface need their own MPPT. For example, if you have panels on two sides of your roof – one row on the east and one on the west – then each needs its own MPPT. There are some exceptions to this depending on the inverter.

Speak to your installer about options available for inverter.

Adding more battery modules to an existing stack (no other system changes)

Most home battery systems today are made up of smaller individual storage modules, which installers stack to create the required storage capacity. Adding storage modules to an existing stack installed before 1 May 2026 does not trigger whole of site compliance requirements for the system. 

What options are available for homes and businesses with a three-phase supply?

Information on this page also applies to customers with three-phase connections who are looking to install or upgrade a solar or battery system.

That includes adding a battery to various install types such as:

• Three-phase inverters (hybrid or non-hybrid).
• Single-phase inverters separately installed on one or more phases. 
• Single-on-three phase inverters from different manufacturers.

In most cases, the simplest option for customers with any hybrid inverter is to add a DC coupled battery.

For non-hybrid or multi-inverter systems, the table below outlines some of the available options.