Thinking About a Battery? Read This Before You Buy (2026 NZ Guide)

Home batteries are having a moment in NZ, but here’s the truth: not all batteries are created equal. Prices can vary wildly and the specs that matter most are often buried in the fine print.

If you’re already across the solar basics (panels generate power in daylight, batteries store it for later), this guide is for the valuable stuff - the checks that stop you buying the wrong battery for your home.

1) Don’t compare batteries by “kWh” alone

Most people shop for batteries like this: “13.5kWh vs 10kWh.”
That’s only half the story.

• kWh = how much energy it can store (think: fuel tank size)
• kW = how much power it can deliver at once (think: how fast the tap flows)

That second one is what decides whether your battery can comfortably handle real-life moments like cooking + heat pump + hot water or starting bigger motors.

Powerwall 3 is strong here because it’s designed for modern homes with heavier loads. It’s also an all-in-one solar + battery system (battery and inverter together), which can mean fewer components on the wall and a cleaner, more efficient setup.

2) The “warranty trap” most people miss: throughput

Battery warranties can look similar at a glance (10 years is common), but the conditions can change everything.

A key term to watch is throughput (the total amount of energy a battery is allowed to deliver over the warranty period).

Easy analogy: it’s like buying a car with 5 years warranty and 100,000km limit.
If you chew through the km limit early, the warranty protection changes.

Tip: Ask your installer:
✅ “Is this warranty unlimited cycles for normal home use?”
✅ “Is there a throughput cap I could hit?”
✅ “Does the way I control the battery affect warranty conditions?”

Good news: For Tesla Powerwall 3, the warranty covers 10 years with unlimited cycles for typical home use modes (self‑consumption, time‑based control, and backup). It’s rated for 13.5 kWh of usable capacity and guaranteed to retain at least 70 percent of that after 10 years, giving you long‑term confidence in both performance and protection.

‍

3) Backup power isn’t all the same

Some batteries are great for shifting solar into the evening, but backup capability can vary massively.

Before you buy, get clarity on:

• Will it back up the whole home, or only selected circuits?
• How much power can it provide during an outage?
• Will it still start ‘heavy’ loads when the grid is down?

This is where premium systems earn their keep - especially if you care about power cuts, storm season or simply keeping life normal when the lights go out.

‍

4) When a battery is worth the extra spend

A battery can be a game-changer when you want to:

• Use more of your own solar at night (instead of buying from the grid)
• Cut down on more expensive power at busy times (if your plan charges more then)
• Add real resilience during outages
• Future-proof for bigger electric homes (EV charging, heat pumps, pool, spa or induction cooktop)

If your goal is purely “maximum payback fast” and you’re home during the day using lots of power while the sun’s up, panels alone can be a great start, but for many Kiwi households, the battery is what turns solar into a 24/7 system, not just a daytime one.

Want the simple answer for your home?

The right battery for you depends on how you use power, what backup you need and how you live each day.

If you’re considering a Powerwall 3 or one of our other GivEnergy battery options, feel free to book a free in-home consultation and we’ll help you work out the right setup and what you’ll realistically get from it.

‍

‍