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With power bills creeping up and those recent storms reminding us how important it is to keep the lights on, solar batteries are becoming a no-brainer for a lot of Kiwis – even in your typical family home. In fact, about a third of Kiwis who install solar are adding batteries to the mix too.
So, what’s the deal? Solar batteries store the extra energy your panels produce, so you can tap into it when you actually need it – like at night, on cloudy days, or during those annoying power cuts.
Most home systems today use lithium-ion batteries (like the Tesla Powerwall or SigenStor), which are compact, efficient, and low-maintenance.
In this guide, we’ll cover the basics: how solar batteries work, what they cost, and why they’re getting so much buzz. If you’re keen to future-proof your home and maybe save a few bucks along the way, let’s dive in.
The key to truly unlocking the value of your solar panels is to use as much of your own solar power as possible. Why? Because every kilowatt-hour you consume from your solar system is a kilowatt-hour you don't buy from the grid, especially during peak times when electricity prices are highest.
Most New Zealand households use the most electricity in the mornings and evenings. This is precisely when your solar panels are either just waking up or winding down. This common mismatch means you often export valuable solar energy during the day, only to buy it back at a higher price later.
But here's how solar battery storage solves this problem. Batteries are clever; they scoop up all that excess solar electricity (you'll see it as that lovely yellow bell curve in the graph below) and safely tuck it away. Then, when the sun goes down and those power prices start to climb – typically in the evenings – you've got your very own stash of free, clean energy ready to go. This is how you genuinely maximise your savings and benefit from your genius solar power system!
One of the best things about having a solar battery? It can be a total lifesaver during a power outage. While the rest of the street goes dark, your battery steps in and keeps the essentials humming—like your fridge, lights, or even medical gear.
(Heads up: not all batteries offer backup power, so make sure to ask about this when you're shopping around.)
Here's how solar batteries work in a power outage:
Solar batteries store excess energy generated by your solar panels so you can use it later—typically at night, during cloudy weather, or in a power outage. This maximises your solar self-consumption and reduces reliance on the grid.
Here are the main types of solar batteries you'll come across:
LFP (Lithium Iron Phosphate)
NMC (Nickel Manganese Cobalt)
When adding a battery to your solar setup, there are two main ways it can connect: AC-coupled or DC-coupled. Most batteries are designed for one or the other—for example, the SolarEdge Home Battery is DC-coupled, while the FranklinWH runs on an AC-coupled setup. A few rare hybrids, like the Pylontech Force H3X, can be configured for either.
Below is a guide to help you figure out what size battery you should install, but a heads up — this part can get tricky. Rather than figure it out yourself, when you get 3 free quotes, simply ask the solar installers for a recommendation. They’ll consider your energy use, solar setup, and goals to suggest the best size for your home.
Look at your power bills—find your average daily usage in kWh (kilowatt-hours). If you're using 20 kWh a day, that gives you a baseline.
Backup during outages? → You might only need 5–10 kWh to run essentials.
Maximise solar self-use? → Match battery size to excess solar generation.
Go off-grid or near to it? → You’ll need enough to cover several days—maybe 15–30+ kWh depending on lifestyle.
If your solar system is small (e.g. 3 kW), installing a massive battery (e.g. 20kWh) won't help much—you won’t have enough excess energy to fill it.
Battery prices scale with size. If money’s tight, a smaller battery (like 5–10 kWh) can still offer decent savings and blackout protection. Many solar battery models these days are modular / stackable, so you go smaller now, and add more modules when the bank allows.
If you are thinking about getting an EV or a spa pool down the track, you might want to oversize slightly to stay ahead.
Solar battery size sweet spot for most NZ homes:
👉 10–20 kWh
The price range for solar batteries is roughly $6,000 to $20,000 NZD. Typically the more storage a battery has, the more it will cost. Other factors that affect the price are the capabilities of the battery, quality of the battery, chemistry used and how long it’s expected to last.
Here’s a quick rundown of some of the products available on the market along with their estimated price:
| Battery Model | Usable Capacity | Battery Chemistry | Power Output | Approximate Price inc GST |
| Solax Triple Power | 6.3 kWh | Lithium Nickel Manganese Cobalt Oxide | 3 kW | $6,500 (uninstalled) |
| Huawei Luna2000 10 KWH | 10 kWh | Lithium Iron Phosphate | 5 kW | $10,500 (uninstalled) |
| BATTERY-BOX PREMIUM HVS | 5.12 kWh | Lithium-Ion Phosphate | 5.1 kW | $10,000 (installed) |
| Tesla Powerwall 3 | 13.5 kWh | Lithium-Ion Phosphate | 5 kW or 10 kW | $19,000 (installed and includes a solar inverter) |
| Sigen Battery 8.0 kWh | 7.8 kWh | Lithium-Ion Phosphate | 4 kW | $10,000 (installed) |
Please note these prices are rough estimates. For accurate quotes, fill in our quote request form here for 3 free quotes.
View and compare more battery storage products available in New Zealand here.
Good news for early solar adopters: you don’t need to replace your entire solar power system to add battery storage. Most grid-connected solar setups can be retrofitted with a solar battery bank, and an AC-coupled battery is often the best choice. These batteries work independently of your existing inverter, making installation simple and compatible with most setups. It’s a cost-effective way to upgrade, boost energy independence, and get more out of your solar investment.
Having a battery ready solar power system is an excellent option if a user is considering adding solar storage at a later date.
Solar batteries are generally low-maintenance, especially modern lithium-based ones like LFP and NMC. Most systems are monitored via apps, making it easy to track performance and spot any issues. As for lifespan, a good-quality battery will typically last 10 to 15 years, depending on usage, temperature, and how deep the battery is discharged regularly. To maximise lifespan, it's best to keep the battery within its recommended temperature range and avoid draining it to zero too often. Most battery models these days run regular software updates automatically to keep things running smoothly.
Exporting solar power to the grid is like getting paid peanuts – we’re talking around 8-18 cents per kWh. So, it’s no surprise your solar system makes sending power to the grid its last priority.
Battery storage will be sent to (1) appliances first (if they are switched on),(2). Only if there is additional excess solar power will the system export solar power to the grid, and thats if you tell the battery to do so. Some energy retailers offer good buy-back prices for battery storage discharged to the grid during peak demand periods (i.e. first thing in the morning and in the evenings). But for most people weighing up this option you probably find it's more valuable to hold to your battery storage, as it's always good to have a reserve amount of storage just in case.
For Power Security - Yes! If you are sick of power outages, or the idea of not having power for a day makes you nervous, then absolutely, solar batteries can be sure to provide a home or business with power during a blackout.
For Financial Return -A solar battery is an expensive item, the financial return on a battery isn't as high as a solar power system alone. But it will help you save on power bills, particularly as the price of electricity in New Zealand continues to climb.
To Reduce Power Bills - Yes! A battery will reduce those pesky power bills on top of the savings already made with a solar power system.
The latest battery models have evolved to become easier and simpler to install – not quite plug-and-play, but getting pretty close! Modern systems like the BYD Battery-Box or Tesla Powerwall 3 are designed with efficiency in mind, meaning they typically take just a few hours to install. The exact duration depends on factors like the system's complexity, site specifics, and the installer's proficiency.
A good rule of thumb: set aside the day, enjoy a cup of tea, and by the afternoon, your new battery will be ready to start saving you money and powering your home.
Chris & Co Installing the Tesla Powerwall 3
The best spot for a solar battery is somewhere cool, dry, and well-ventilated. Heat is the enemy of battery life, so avoid direct sun and uninsulated garages or sheds that get hot in summer. Common locations include inside a garage, under a carport, or on a shaded exterior wall—some batteries are weatherproof, others aren’t, so check the IP rating. If you are in a flood-prone area, consider raising it off the floor with a stack of concrete tiles or wall mounted if possible. If indoors, make sure there’s airflow and easy access for servicing. Bonus tip: keep it close to your switchboard and inverter to minimise wiring costs and energy loss.
For further reading:
Read our blog articles about solar battery storage here>
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