Solar panels make cheap power at midday; households use most of theirs in the morning and evening. A home battery closes that gap, storing your sunshine until you actually need it. Here's how batteries work in the New Zealand context and how to tell whether one belongs in your system.
Why Batteries Change the Maths
Without a battery, surplus solar is exported to your retailer at a buy-back rate that's typically well below what you pay to import power. A battery lets you keep that surplus and use it in the evening peak instead, swapping a low sell price for a high avoided-purchase price on every stored kilowatt-hour.
Backup When the Power Goes Out
A battery with backup capability keeps your essentials (fridge, lights, internet, medical equipment) running through an outage. In parts of the country where storms and network interruptions are a fact of life, this is often the deciding factor as much as the savings.
What Size Battery?
Common home batteries store roughly 10–16kWh, enough to carry a typical household's evening and overnight use. The right size depends on how much surplus your panels generate and what you want to back up. We size storage from your actual usage, not a brochure.
Batteries Let You Install More Solar
Here's a detail many people miss: on standard single-phase power, a 10kW inverter can host up to 13.3kW of panels (the 33% oversizing allowance). Add a battery and that allowance grows to as much as 200%, up to around 20kW of panels, because the extra generation has somewhere useful to go. If you want maximum solar on a single-phase home, a battery is what unlocks it.
The Hardware We Install
EFS Solar installs premium battery systems from Energizer and Sigenergy, matched to your inverter and backed by 10-year warranties, with installation by licensed electrical workers. Learn more about our battery service or get a tailored quote, $0 upfront options are available.
Starting from scratch? Read our solar system size guide to get the panels right first.