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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.
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.
Households tend to use the most electricity in the mornings and evenings—right when solar panels aren’t producing their best. As shown in the graphs below, this mismatch can be solved with battery storage, letting you maximise the benefits of your solar system.
Solar batteries function by taking excess solar electricity (shown in the yellow bell shaped curve) and storing the electricity in batteries. By storing this excess electricity, users can consume power whenever they like, typically during non-sunny hours like evenings or cloudy days. Evenings is when power prices are typically at their highest, this is where you can really maximise your savings.
Solar batteries can be a lifesaver during a power outage. They store excess energy generated by your solar panels, so when the grid goes down, you’ve got a backup power source to keep essential appliances running.
Note: not all batteries offer this feature, be sure to ask when making a purchase.
Here's how solar batteries work in a power outage:
Prioritised for maximum efficiency, solar power is sent to where it is needed most.
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) |
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.
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.
Battery storage technology; it's a race to develop the ultimate solar battery storage system. Lithium-ion battery technologies are the most common battery on the market. Lithium-ion batteries are smaller, lighter and store more energy than traditional lead-acid batteries.
Lithium-ion batteries are found in mobile phones, laptops and electric vehicles - increased demand for these products has prioritised economies of scale for lithium-ion, with the cost dropping roughly 20% each year.
The reason lithium-ion is used for solar batteries includes:
When choosing a solar battery, consider factors like capacity—smaller batteries (5 kWh) are great for light use, while larger ones (10-15 kWh) suit bigger households or higher demands. Look for high cycle life to ensure durability, and prioritise efficiency for maximum use of stored energy. A warranty of at least 10 years offers peace of mind, and make sure the battery is compatible with your current solar system.
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.
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
For further reading:
Read our blog articles about solar battery storage here>
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