Clients ask The Conduction Company three things about home batteries: what one costs, how big it needs to be, and whether it can be added to the solar they already have. The estimates below are for standard installation of a home battery. The Conduction Company confirms final pricing after a property assessment.
Adding a 6 kWh battery to a Sigen Hybrid costs about $8,000 including GST, installed, in The Conduction Company's price book. A new solar system with a battery starts from about $20,800 including GST, installed. A system from another installer is priced once its inverter has been checked.
What does adding a battery to an existing solar system usually cost?
The solar battery price depends on what is on your roof now. The Conduction Company prices it from its own current price book, the same figures it puts on its quotes.
We quote on facts, not guesses
Before we give you a price, we carry out a proper assessment of your property and how you'll use your home battery. That way you know exactly what you're buying and the total cost, with no surprises. Clear expectations from the outset, start to finish.
The estimates below are for standard installation of a home battery.
The Conduction Company confirms final pricing after a property assessment.
The Conduction Company's home battery prices, from its current price book, each supplied and installed with labour included, all including GST:
A 6 kWh battery added to a Sigen Hybrid. About $8,000 including GST, installed. For a Sigen Hybrid SP2 or TP2 inverter already installed and running on solar alone. It covers a SigenStor battery controller, one 6 kWh battery module on a floor base with seismic anchors, the cable back to the Hybrid, and testing.
A 9 kWh battery added to a Sigen Hybrid. About $9,300 including GST, installed.
A second 6 kWh module on a SigenStor already installed. About $5,700 including GST, installed.
Backup power in a power cut. A Sigen Gateway adds about $2,700 including GST, installed, on a single-phase home. Without one, the battery does not keep the power on in a cut.
The Conduction Company's recent quotes back these figures up. For the same homes, choosing a 6 kWh battery instead of a battery-ready system added about $6,700 to $7,800 including GST. On those quotes, fitting the battery at the start cost a little less than adding it later.
A battery for a system another installer put in is quoted individually, because it depends on the inverter. For what a whole new system costs, see The Conduction Company's guide to what solar panels cost in Auckland, and how long they take to pay back.
Can a battery be added to an older solar system from another installer?
Often, yes, says The Conduction Company, if the inverter is a hybrid. A hybrid inverter is built to take a battery, although only certain battery models will work with it.
A standard grid-tie inverter has nowhere to connect a battery. Then The Conduction Company has two options. One is a battery system with its own inverter, which works alongside the old one on the house's wiring (installers call this AC coupling). The other is swapping the old inverter for a hybrid that a battery can be added to. Which suits you depends on the age and condition of the inverter you have now.
What is the best solar battery in NZ?
For The Conduction Company, it is Sigenergy, its first choice and main battery supplier in New Zealand. "They're just the market leaders," says Jordan Statham, director of The Conduction Company and a registered electrician and electrical inspector.
Sigenergy arrived in recent years and, in Jordan's view, has led the market since on how well its systems work and how easy they are to use, with an excellent app and plenty of technology packed in. "Just an excellent product," he says. "Works really well, and all of the modern functionality and technology that comes with it is just unbeatable."
The Conduction Company's most recent battery quotes were for a Sigenergy SigenStor system with one 6 kWh battery module, and the option to add a second 6 kWh module for 12 kWh in total. SigenStor batteries use lithium iron phosphate cells, come in modules of 5.2, 6.0, 7.8 or 9.0 kWh you can use, and stack up to six on one controller.
Tesla Powerwall installation: does The Conduction Company do it?
Not typically. The Conduction Company installs Sigenergy as its primary home battery, and it still prefers Sigenergy over Powerwall. Jordan Statham says Powerwall has its benefits and is not a bad system, and some clients who are big Tesla fans really want one.
Is a home battery worth it without solar panels?
In most cases, no, says The Conduction Company. A battery stores power, it does not make it. On its own it can only save money by buying power when it is cheap and using it when it is dear, and the gap is not big enough to pay a battery back quickly. "The payback period is enormous," says Jordan Statham.
There is no national or Auckland government grant for a home battery today. With no help on the cost and today's power prices, The Conduction Company does not recommend a battery on its own. It recommends pairing one with solar panels, so the battery stores your own power instead of selling it to the grid for a low rate.
Some newer companies do sell a battery with no panels. Aotea Energy, for example, sells a battery and also becomes your power company, charging the wholesale price of electricity, which changes every half hour, plus a monthly fee. The battery fills up when wholesale power is cheap, usually overnight, and runs the house through the expensive peaks. It can cut bills, but you take on the risk of price spikes. In August 2024, the Electricity Authority reports, wholesale prices went over 80 cents a kWh at times, before lines charges and GST, and the company itself says bills can be higher in months like that.
Is a 10kW battery enough to run a house?
For an evening, yes. For a full day, no, says The Conduction Company. Battery size is measured in kilowatt-hours (kWh), so a "10kW battery" usually means a 10 kWh battery.
How long it lasts depends on what is running. Anything that makes heat uses a lot of energy, so cooking on a freestanding oven from the battery runs it down quickly. With just the lights and basic electronics on, Jordan Statham says it could get you through to bedtime, and maybe until the sun starts producing again in the morning.
As a rough guide from The Conduction Company: a 10 kWh-class SigenStor module holds about 9 kWh you can use. The average New Zealand home uses about 6,836 kWh a year, about 18.7 kWh a day, on MBIE's figures for the year to March 2026. So one battery that size covers a little under half a day, and an oven running for an hour uses about 2.4 kWh of it on Powershop's appliance guide.
How long does a home battery last?
Plan on 10 to 15 years of useful life, says The Conduction Company. Sigenergy and Tesla both guarantee their home batteries for 10 years, with at least 70% of the original storage left at the 10-year mark.
Sigenergy's cover also ends early if a set amount of power has gone through the battery first, and it needs the system kept online for the full 10 years. Without internet access, Sigenergy's cover is 5 years.
Jordan Statham guessed a battery might last up to about 20 years, losing efficiency fairly steadily. The measurements mostly agree on the shape. A study of home batteries in Germany, published in Nature Energy in 2024, found they lose about 2 to 3% of their storage each year, close to a straight line. At that rate a battery can still be running at 20 years, but holding only around half of what it did new.
Where in a house does a battery go, and where should it never go?
Never in a bedroom, living room or other habitable room, says The Conduction Company, and a garage is usually the best place. The rules are in AS/NZS 5139, the battery safety standard, which the wiring rules, AS/NZS 3000, require installers to follow.
The standard also keeps a battery out of ceiling spaces, wall cavities, under stairs and escape routes, and at least 600 mm to the side of, and 900 mm below, any window or vent that serves a habitable room. A battery can go on a wall with a living space on the other side only if that wall is a non-combustible barrier, such as masonry, concrete or compressed cement sheet.
That is why The Conduction Company prefers an internal garage, out of the path of a car. The standard asks installers to protect a battery from knocks, and gives a vehicle in a garage as its own example. A garage also keeps the battery out of the weather, so it stays cleaner and its casing lasts longer.
Outdoors is possible. The SigenStor is built to IP66, so it can live outside, but Sigenergy recommends a sheltered spot out of direct sun and rain, and well away from the sea.
Can a battery charge from the grid overnight on a cheaper rate?
Yes, says The Conduction Company. Some batteries can be set to charge overnight on a plan with cheaper night power, and as part of a solar system that can add to your savings.
Several Auckland power companies offer cheaper night rates, such as Contact's Good Charge and Meridian's Night Saver, and the rate depends on your address. As a reason to buy a battery on its own, though, The Conduction Company does not recommend it: the saving does not come close to warranting the cost of the battery. Some power is also lost going into and out of any battery.
What do clients expect from a battery that it does not deliver?
To run the whole house overnight. In The Conduction Company's experience, many clients first expect one standard battery to run everything for hours, and a standard 6, 12 or even 18 kWh battery does not last as long as people think.
Two limits are at work. The kWh figure is how much energy the battery holds, like the size of a fuel tank. The inverter's kW rating is how much power can flow at once, like the width of the fuel pipe. A full battery behind a small inverter still cannot run an oven, a kettle and a heat pump together.
Backup is separate again: a Sigenergy battery keeps the power on in a cut only with a Sigen Gateway fitted. For off-grid homes, where the goal is to run on solar for as long as possible, The Conduction Company fits several batteries in stacks, and its guide to running a house on solar power only covers that.
Are home batteries a fire risk, and how do you install them safely?
A battery fire is unlikely, but not impossible, says The Conduction Company. Batteries hold volatile chemicals to store that much energy, and the electrical standards control where they can go for exactly that reason.
Modern home batteries such as the SigenStor use lithium iron phosphate cells, one of the more stable lithium chemistries. Sigenergy adds several layers of protection, including temperature monitoring of the cells, an internal fire extinguishing kit and heat-resistant insulation.
The Conduction Company follows the standard's placement rules on every install, and keeps each battery well away from anything that could hit it. "If you were to ever have an impact, let's say with a vehicle, that could breach the encasement of the battery," says Jordan Statham. "That could become a real problem."
In short
In The Conduction Company's price book, adding a 6 kWh battery to a Sigen Hybrid costs about $8,000 including GST, installed, and a new solar system with a battery starts from about $20,800 including GST, installed. A hybrid inverter can usually take a battery; a standard inverter needs a battery with its own inverter, or a swap. A 10 kWh battery runs a house for an evening, not a day, and lasts about 10 to 15 years of useful life. On its own, without panels, a battery rarely pays its way, so The Conduction Company pairs it with solar and fits it outside the living areas, usually in the garage.
If you are thinking about adding a battery, The Conduction Company is happy to help with solar panel and battery installation in Auckland.
Frequently asked questions
What is the cost of solar panels and a battery in NZ?
From about $20,800 including GST, installed, for a new solar system with a battery, in The Conduction Company's price book, depending on the size of the system and the roof. The Conduction Company confirms the final price after a property assessment.
Can a battery be added to my solar system if I only have a Sigen Hybrid inverter?
Yes, on a Sigen Hybrid SP2 or TP2. The Conduction Company adds a SigenStor battery controller and battery modules on a floor stack beside the Hybrid, which stays on the wall as it is. An older first-generation Hybrid needs a licence switched on first, so The Conduction Company checks which one you have. A 6 kWh battery costs about $8,000 including GST in its price book.
Does a home battery give backup power in a power cut?
Only with the right equipment, says The Conduction Company. A Sigenergy battery needs a Sigen Gateway to keep the power on in a cut, about $2,700 including GST on a single-phase home in The Conduction Company's price book.
How long will a 10kWh battery last?
Through an evening of lights and basic electronics, and maybe to the morning, says The Conduction Company, but not a full day. It holds about 9 kWh you can use, a little under half of an average New Zealand home's daily use, and cooking or heating runs it down fast.
Is a 20 kW battery enough to run a house?
A 20 kWh battery holds about one day of an average New Zealand home's use, says The Conduction Company. Even so, it rarely runs everything overnight: heating, cooking and hot water drain it fast, and the inverter's kW rating limits how much can run at once.
Are solar batteries worth it?
Paired with solar panels, a battery can add savings by storing your own power for the evening. On its own, without panels, The Conduction Company does not recommend one, because the payback period is enormous.
