Compare 40 kWh home batteries
GoodWe 40 kWh usable and SolaX 36.7 kWh usable side by side
Single-phase · Without backup · Figures from the manufacturers' datasheets, prices from our written quotes.
 |  | |
|---|---|---|
| Installed price, rebate taken off | $13,977 | $13,459Lower |
| Energy you can use | 40 kWhRated 41.6 kWhMore | 36.7 kWhRated 40.8 kWh |
| Price per usable kWh | $349Lower | $367 |
| Blackout backup power | 10 kWSwitches over in 4 ms | 10 kWSwitches over in under 10 ms |
| Whole-home backup | Built in | Built in |
| Power it can supply at once | 10 kW | 10 kW |
| Time to fill from the grid | About 4 hoursAt up to 10 kW | About 3.5 hoursAt up to 10 kWFaster |
| With your existing solar | Works beside your inverterNew panels can connect to it too | Works beside your inverterNew panels can connect to it too |
| Where it can go | Floor onlyIP66 · -20 to +55 °C | Floor onlyIP66 · -30 to +53 °C |
| Inverter noise | 35 dB | Under 35 dB |
| Warranty | 10 yearsKeeps at least 70% of its capacity | 10 yearsKeeps at least 70% of its capacity |
| Add more battery later | Up to 12 modulesUp to 96 kWh, any time | Up to 13 modulesUp to 59.7 kWh, within a year of installation |
| Virtual power plants | Amber, ENGIE | GloBird |
| Solar panels it can take | 20 kW | 20 kW |
| Size installed | H 1,845 × W 800 × D 270 mmInverter on top, heaviest piece 79 kg, about 421 kg in total | H 1,629 × W 600 × D 376 mmInverter on the wall 557 × 590 × 180 mm, heaviest piece 47 kg, 399 kg in total |
| View the quoteBook an InspectionQuoted as GoodWe 41.6 kWh single-phase with 10 kW inverter | View the quoteBook an InspectionQuoted as SolaX 40.8 kWh single-phase with 10 kW inverter | |
Next step
40 kWh usable · $13,977
36.7 kWh usable · $13,459
Why prices differ at about 40 kWh
This group has four single-phase systems from three brands, holding 36 to 43.5 kWh usable. Installed prices run from $13,459 to $14,526 without backup, or $334 to $403 per usable kWh. Backup is extra on every system. Partial backup adds $500 on GoodWe and SolaX and $1,456 on Sigenergy, which includes a Sigen Gateway.
This group has five three-phase systems from three brands, holding 36 to 40 kWh usable. Installed prices run from $14,128 to $15,519 without backup, or $353 to $431 per usable kWh. The lowest price per usable kWh here, GoodWe 40 kWh usable at $353, has a 10 kW inverter that takes solar panels up to 20 kW. Most systems here have 15 kW inverters that take up to 30 kW. Backup is extra on every system. Partial backup adds $500 on GoodWe and SolaX and $1,681 on Sigenergy, which includes a Sigen Gateway.
Every system here uses LFP battery cells, with batteries and inverters rated IP65 or IP66, and a battery warranty that keeps at least 70% of capacity at the end of its term.
What changes at about 40 kWh
The federal battery rebate (Cheaper Home Batteries Program) is worked out on usable energy, at a rate of $252 per kWh on the quote date: 100% of the rate for the first 14 kWh, 60% of the rate for 14 to 28 kWh, 15% of the rate for 28 to 50 kWh. In this group it comes to $5,920 to $6,216 per system, or $143 to $164 per usable kWh, less per kWh than on smaller systems. The rebate is set by the installation date, and eligibility is confirmed before installation.
Going one size up with the same brand, supply and inverter adds $549 to $3,360 from this group, or $157 to $432 for each extra kWh of usable energy.
Each step up (7)
| System | From | To | Adds | Per extra kWh |
|---|---|---|---|---|
| GoodWe, single-phase, 10 kW inverter | 40 kWh usable | 43.5 kWh usable | $549 | $157 |
| GoodWe, single-phase, 10 kW inverter | 43.5 kWh usable | 48 kWh usable | $1,946 | $432 |
| GoodWe, three-phase, 10 kW inverter | 40 kWh usable | 48 kWh usable | $3,155 | $394 |
| GoodWe, three-phase, 15 kW inverter | 40 kWh usable | 48 kWh usable | $2,495 | $312 |
| Sigenergy, single-phase, 10 kW inverter | 36 kWh usable | 45 kWh usable | $2,898 | $322 |
| Sigenergy, three-phase, 15 kW inverter | 36 kWh usable | 45 kWh usable | $2,736 | $304 |
| SolaX, three-phase, 15 kW inverter | 36.7 kWh usable | 45.9 kWh usable | $3,360 | $366 |
Packages are named by their rated size. We group them by usable energy, so GoodWe 45 kWh (43.5 kWh usable) is in this group.
How we compare
Prices come from Sunbridge Energy's written quotes, issued 20 October 2026 and valid until 19 November 2026. Each includes GST, the listed equipment and standard installation and commissioning, with the federal battery rebate (Cheaper Home Batteries Program) deducted at the rate for an installation on the quote date. The rebate is set by the installation date, and eligibility is confirmed before installation. Prices are the same in NSW, VIC and QLD.
These options and site work can add to a price, and each written quote sets them out: garage installation +$500, new concrete slab +$250, cable beyond 5 m +$30 per metre, remove old inverter +$300, remove old battery +$600, remove old inverter and battery +$900 and switchboard upgrade up to $1,500.
Specifications come from the manufacturers' datasheets for each battery module and inverter. Where a datasheet we hold leaves a figure out, we say so rather than estimate it. For 32 of the 62 systems, the inverter datasheet gives no separate limit for power drawn from the battery, so we show the inverter's output and, where it is lower, the batteries' own rating instead of a combined figure. Price per usable kWh and warranty energy are calculated by Sunbridge from these figures.
We only compare systems built for the same supply, and we group sizes by usable energy. Brand comparisons pair systems with usable energy within 10% and the same inverter output, and say so when they can't. A figure counts as different only when the gap is large enough to matter: $100 of price, $10 per usable kWh, 0.5 kWh of usable energy, 0.5 kW of inverter output, 1 kW of solar input, one year of warranty, 5% of warranty energy or 5 kg of weight.
We supply and install every system on this page and earn from each installation, so this is not an independent review. We only list the six brands we install. Brands we don't install, such as Tesla, Sungrow and BYD, are not here.
Questions about home batteries of about 40 kWh
How much does a home battery of about 40 kWh cost installed?
We install nine systems with 35 to 45 kWh of usable energy. Single-phase systems cost $13,459 to $14,526 and three-phase systems $14,128 to $15,519, including GST and standard installation, after the federal battery rebate and without backup. Each links to its written quote, valid until 19 November 2026.
Which battery of about 40 kWh is best?
No single system is best for every home. Among single-phase systems here, SolaX 36.7 kWh usable has the lowest installed price ($13,459, with a 10 kW inverter) and GoodWe 43.5 kWh usable has the lowest price per usable kWh ($334). Among three-phase systems, GoodWe 40 kWh usable has the lowest installed price ($14,128, with a 10 kW inverter). Compare inverter size, solar input and warranty too, which the list above shows.
Why do systems of about 40 kWh differ so much in price?
Price per usable kWh runs from $334 to $403 for single-phase systems and $353 to $431 for three-phase systems. Among three-phase systems, the lowest, GoodWe 40 kWh usable at $353, has a 10 kW inverter that takes solar panels up to 20 kW, while most have 15 kW inverters that take up to 30 kW. Backup is extra on every system. Partial backup adds $500 on GoodWe and SolaX and $1,681 on Sigenergy, which includes a Sigen Gateway.
Why is the rebate per kWh lower on bigger batteries?
The federal battery rebate (Cheaper Home Batteries Program) is worked out on usable energy, at a rate of $252 per kWh on the quote date: 100% of the rate for the first 14 kWh, 60% of the rate for 14 to 28 kWh, 15% of the rate for 28 to 50 kWh. In this group it comes to $5,920 to $6,216 per system, or $143 to $164 per usable kWh, less per kWh than on smaller systems. The rebate is set by the installation date, and eligibility is confirmed before installation.
Is about 40 kWh the right size for my home?
Look at how much electricity you use between about 4pm and 7am, in your retailer's app or on your bill. A battery's usable energy is what it can supply over that time. We work through the size with you at the inspection.
Which brands have systems of about 40 kWh?
Three: GoodWe, Sigenergy and SolaX. The Anker SOLIX, EcoFlow and ESY systems we install are all smaller.
More comparisons
What happens when you book
Choose a time and the inspection goes straight into your local branch's calendar. It takes about 20 minutes. We confirm your supply, where the system goes and whether anything changes the price, before anything is final.
Sunbridge Energy supplies and installs every system here through its Sydney, Melbourne, Brisbane and Gold Coast branches. Sigenergy Certified Installer · GoodWe Verified Installer, installer code G10000622 · New Energy Tech Consumer Code Approved Seller.