Home battery sales outpace new solar systems for first time ever, in sign of boom to come

Australia’s battery storage market is booming – but not booming equally for all players.

Recent data shows the market is evolving rapidly: batteries are not only selling in record numbers, but their average size is increasing, and retrofit systems are surging ahead of new PV + battery installations.

These shifts are creating new winners and losers in the market, with product-market fit emerging as a key driver of brand success.

Batteries now outpacing PV – in both sales and size

For the first time ever, more battery systems were sold than PV systems in May 2025. Preliminary data shows 1.4 battery systems installed for every PV system — an extraordinary milestone.

But it’s not just about the number of installations. Battery size is booming too. In May, the typical installed battery size jumped to 15kWh — up from the historical norm of around 10kWh.

Why? The new federal battery subsidy is playing a major role.

With the subsidy covering roughly one-third of a typical ESS (energy storage system), consumers are faced with a choice:

• Pocket the savings, or
• Use the subsidy to buy a larger battery.

It appears many are choosing the latter — a rational choice when the subsidy can effectively provide a 50% capacity uplift at no additional cost.

Retrofits rising fast

Another major trend is the growing dominance of retrofit battery systems.

Right now, retailers are fielding a wave of inbound interest from existing solar owners eager to add batteries to their PV systems — driven in part by the subsidy. This is leading to a surge in standalone ESS sales, as opposed to new PV + battery systems.

Preliminary May data confirms this: ESS-only systems grew fastest and look set to become the dominant purchase category if trends continue.

This has important implications for battery brands:

• Retrofittable brands are at a clear advantage.
• Stackable batteries, which allow customers to easily add more capacity, are benefiting most.
• Monolithic battery designs face greater challenges in this market, as upsizing isn’t always feasible or cost-effective.

Conclusion

As the federal subsidy drives unprecedented growth, the Australian battery market is undergoing structural change. Retrofit sales, battery size, and inverter trends are reshaping competitive dynamics.

Manufacturers, distributors and retailers who align their offerings with these trends will be well-positioned to capitalise on this battery boom — and those who don’t may struggle to keep pace.

SunWiz provides Australia’s leading battery market insights, with monthly tracking of volumes, attachment rates, brand performance, battery sizes, inverter trends, pricing and more. To learn more about SunWiz’s expanded Battery Market Subscription, visit www.sunwiz.com.au.