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Home Battery Calculator: Which Battery Is Right for Me? 60-Second Quiz

Checked and updated by our licensed electricians: October 2026

Which home battery is right for me? Answer six quick taps and see, in plain words, the battery size range and the brand that fits your home: Sigenergy, our premium battery, or GoodWe, mid-tier and very high quality. You will also see whether you are likely to need more solar. No prices, no sales pitch, and no details needed to see your result.

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How we size a home battery

The quiz is a starting point. The real design comes from 1 or 2 of your recent power bills, so the battery matches what you actually use, not a generic package. There are three common situations:

  • No solar yet: we size the solar and battery together from your real use.
  • Solar that is not quite enough: we check whether it can cover your day and charge a battery for the night, and design the extra panels if not. See adding more solar panels.
  • Solar that is enough: it is a battery on its own. See adding a battery to existing solar.

Want to work it out yourself first? Read how big a battery do you need and how to read your power bill to size solar and a battery.

Battery sizes we install

Both batteries grow in modules, so you can start with the size that fits now.

  • GoodWe ESA: 8 kWh modules, so 8, 16, 24, 32 or 40 kWh. Mid-tier and very high quality. GoodWe batteries.
  • Sigenergy: 9 kWh modules, so 9, 18, 27, 36 or 45 kWh. Our premium choice. Sigenergy batteries.

We also install Sungrow, SolaX and Tesla batteries. Compare them in Sigenergy vs GoodWe vs Tesla. Living close to the beach? Read solar batteries near the coast first.

Rebates and blackout backup

We build the federal Cheaper Home Batteries rebate and the solar STC rebate into every design and handle the paperwork. Work out your rebate with our battery rebate calculator. For blackouts, see blackout backup batteries and whole-home vs essential-circuit backup.

See the batteries we have put in near you on our map of our installs by town.

How the quiz works and what it assumes

Six taps, no details, and the result is on the screen: free, instant and nobody to talk to. The optional form afterwards is for people who want us to size the battery properly from their bill. Here is the maths behind the result, so you can judge it for yourself.

  • Daily use from your bill. A quarterly bill under $300 is treated as about 10 kWh a day, $300 to $600 as 18 kWh, $600 to $1,000 as 28 kWh and over $1,000 as 40 kWh (Northern Rivers tariffs, 2026). “Not sure” uses 18 kWh, the most common bracket.
  • How much of that happens at night. If nobody is home in the day, about 60% of your use is outside solar hours; someone home some days, 50%; someone home most days or working from home, 45%. That night share is what a battery has to cover.
  • EV and backup. An EV you already have adds about 6 kWh a night of charging; one coming in the next couple of years adds 3 kWh. If blackout backup is very important, 4 kWh is added as reserve so the battery is not empty when the grid drops.
  • Real module steps. The need is rounded to the nearest module and shown as a one-module band: GoodWe ESA in 8 kWh modules (8 to 40 kWh), Sigenergy in 9 kWh modules (9 to 45 kWh). The minimum is one module.
  • Brand fit. “Premium and the best app” points to Sigenergy; “very high quality for less outlay” points to GoodWe ESA; “guide me” shows both, and leans to Sigenergy if an EV is in the picture because its optional DC charger works with the battery.
  • Do you need more solar? Under 5 kW of existing solar usually cannot run the house and fill a battery; 5 to 10 kW is often enough unless your bill is over $600 a quarter or you charge an EV; over 10 kW normally fills any home battery. No solar yet means we design both together.

It is a sizing guide, not a design. The real answer comes from your power bill (every page) and a site visit. See how to read your power bill to size solar and a battery and how big a battery do you need.

What the battery the quiz suggests would cost

Prices move in module steps because the batteries do. Adding a battery to existing solar today, including GST and installation, after the estimated federal rebate: GoodWe ESA 8 kWh about $7,300 to $8,300, 16 kWh $8,600 to $9,800, 24 kWh $10,600 to $12,100, 32 kWh $13,200 to $15,100; Sigenergy 9 kWh $8,500 to $9,600, 18 kWh $10,700 to $12,200, 27 kWh $14,200 to $16,200, 36 kWh $17,800 to $20,200. Solar and a battery together starts from $12,500 (6.6 kW with GoodWe 16 kWh) or $14,700 (6.6 kW with Sigenergy 18 kWh) after rebates.

What moves a job inside or above those ranges: the switchboard (older boards need safety switches or an upgrade to connect a battery to current standards), three phase, the roof type and height for the solar, long cable runs to a shed, and extra backup hardware on very large homes. We check all of that at a face-to-face site visit before anything is quoted, so nothing is added on install day. Run your own answers through the solar and battery price calculator for a range with your roof, storeys and switchboard taken into account, or see battery prices by size and what decides the cost of solar and a battery.

Rebate step-down dates by battery size

The federal Cheaper Home Batteries rebate is a number of small-scale technology certificates (STCs) per kilowatt-hour of usable battery capacity, set by the date the battery is installed, not the date you sign. The factor is 6.8 certificates per kWh for installs up to 31 December 2026, 5.7 from 1 January 2027 and 5.2 from 1 July 2027, then it keeps stepping down twice a year. The first 14 kWh earns the full rate, 14 to 28 kWh earns 60% and 28 to 50 kWh earns 15%; nothing above 50 kWh. At about $38 a certificate, here is what that means for the sizes we install most:

Battery Installed by 31 December 2026 Installed 1 January to 30 June 2027 Installed 1 July to 31 December 2027 Installed 1 January to 30 June 2028
GoodWe 16 kWh (16.64 kWh usable) $3,990
105 certificates		 $3,344
88 certificates		 $3,078
81 certificates		 $2,698
71 certificates
Sigenergy 18 kWh (18.08 kWh usable) $4,218
111 certificates		 $3,534
93 certificates		 $3,230
85 certificates		 $2,850
75 certificates
GoodWe 24 kWh (24.96 kWh usable) $5,282
139 certificates		 $4,446
117 certificates		 $4,028
106 certificates		 $3,572
94 certificates
Sigenergy 27 kWh (27.12 kWh usable) $5,624
148 certificates		 $4,712
124 certificates		 $4,294
113 certificates		 $3,800
100 certificates
GoodWe 32 kWh (33.28 kWh usable) $5,966
157 certificates		 $5,016
132 certificates		 $4,560
120 certificates		 $4,028
106 certificates

Certificate prices move with the market, so these are estimates at $38 each. Your quote shows the exact figure for your battery and install date, already taken off the price. Solar certificates step down too: a 6.6 kW system earns 45 certificates ($1,710) when installed in 2026 and 36 ($1,368) from 1 January 2027, because the deeming period shortens by a year every January.

Check any size and date on the battery rebate calculator: it needs no details.

Which size real Northern Rivers homes chose

Batteries our own team installed, from our STC claims (town and system only), so you can see what each quiz band looks like in a real home.

Quiz band Town What we installed Why that size Case study
8 to 9 kWh Mullumbimby Sigenergy 9.04 kWh with 6.65 kW solar Small household, modest night use; one module covers the evening. Read the story
8 to 9 kWh Pottsville Sigenergy 8.06 kWh with 6.37 kW AIKO solar Coastal home, low bill; a single module plus efficient panels. Read the story
16 to 18 kWh Lennox Head GoodWe 16.64 kWh with 8.55 kW Jinko solar The most common Northern Rivers family size: two modules, very high quality for less outlay. Read the story
16 to 18 kWh Byron Bay Sigenergy 16.12 kWh with 10.45 kW AIKO solar Premium pick with a bigger roof array to fill it in winter. Read the story
16 to 18 kWh East Lismore Sigenergy 16.12 kWh with 6.79 kW AIKO solar Suburban home, someone home in the day; 6.8 kW is enough to run the day and charge the battery. Read the story
24 to 27 kWh Tyalgum GoodWe 24.96 kWh with 6.65 kW Jinko solar Rural Tweed Valley home where blackout backup mattered: three modules of reserve. Read the story
24 to 27 kWh East Ballina Sigenergy 27.12 kWh with 8.55 kW Jinko solar Larger bill and evening-heavy use; three Sigenergy modules. Read the story
32 to 36 kWh Ocean Shores Sigenergy 32.24 kWh with 13.3 kW AIKO solar High use with a big array to match; backup through long outages. Read the story
40 kWh and up Alstonville area Sigenergy 40.3 kWh with 16.92 kW Trina solar Acreage with pumps and sheds; designed from the bills, beyond the quiz. Read the story

Off-grid and acreage homes are sized differently again: see our off-grid Mullumbimby hinterland install and days of autonomy for off-grid batteries.

Worried about outages? See how long your likely battery would run the house with the blackout battery runtime calculator, and find every free calculator on our free calculators page.

Want the long read before you decide? The Northern Rivers home battery buyer’s guide covers sizing, brands, the rebate dates and backup; already have solar? Run the battery-ready checker.

Questions we get asked

Which home battery is right for me?

It depends on how much power you use at night, whether you already have solar, how much blackout backup matters and whether an EV is coming. We install two main batteries: Sigenergy, our premium choice, and GoodWe, mid-tier and very high quality. The quiz above gives a likely size range and the brand that fits your answers, and our electricians confirm it from your power bill.

What size battery do I need?

Enough to carry your evening and overnight use, plus some headroom for blackouts or an EV. GoodWe ESA batteries come in 8 kWh modules (8, 16, 24, 32 or 40 kWh) and Sigenergy in 9 kWh modules (9, 18, 27, 36 or 45 kWh). Many Northern Rivers homes end up with two or three modules. We size yours from 1 or 2 recent power bills.

Sigenergy or GoodWe: what is the difference?

Both are quality batteries we are happy to put our name to. Sigenergy is the premium option: a stackable all-in-one system with a polished app and an optional EV charger that works with the battery. GoodWe ESA is an all-in-one unit that gives very high quality for less outlay. Both can back up the whole home in a blackout. See our Sigenergy vs GoodWe vs Tesla comparison for the detail.

Do I need more solar to add a battery?

Not always. If your solar already covers your daytime use and has power left over to charge a battery, a battery on its own is enough. Smaller or older systems often need extra panels to fill the battery. We check your inverter and your bills before we recommend anything.

Will a battery keep my power on in a blackout?

With the right setup, yes. A typical install from us gives full home backup, running all circuits unless you ask us to leave some out, such as an EV charger. We set it up and show you how it works on install day.

Is the quiz result my final system?

No. It is a guide to start the conversation. The real sizing comes from your power bill, and every job has a face-to-face site visit before install day to check the battery position and your switchboard, so there are no surprises.

Do I need to give my details to see the quiz result?

No. Six taps and the result is on the screen, free and instant, with nobody to talk to. The form underneath is optional, for people who want us to size the battery properly from their power bill.

What does the quiz get wrong?

It cannot see your bill, your tariff, your pool pump timer or your air conditioning habits, so it works from averages for the Northern Rivers. A home with a pool or ducted air can need a module more than the band shows; a frugal home can need less. That is why the real sizing comes from every page of your bill.

Should I get the biggest battery the rebate allows?

Usually not. The rebate flattens after 14 kWh (60% rate to 28 kWh, 15% to 50 kWh), so a 32 kWh GoodWe earns about $5,966 today against $3,990 for 16 kWh, while costing $6,600 more before rebates. Go bigger for backup hours, an EV or genuine night-time use, not for the rebate.

Can I add modules later?

Yes with both systems. Sigenergy modules stack in minutes; GoodWe ESA takes extra 8 kWh modules up to 40 kWh. The later modules earn whatever rebate factor applies on their install date, and a small amount of commissioning labour applies, so if you know you will want more, it is cheaper to fit it on day one.

What if the quiz says I need more solar?

It means your current panels probably cannot run the house in the day and fill the battery too. We check your inverter and bills before recommending anything; often a few extra panels on a second string do it, and a new system is only suggested when the old inverter is at the end of its life. See adding more panels to an existing system.

Which batteries do you install besides GoodWe and Sigenergy?

Sungrow, Solax and Tesla Powerwall where they suit the home, and we are accredited for all of them. The quiz sizes in GoodWe and Sigenergy modules because those are the two we recommend most for Northern Rivers homes; the same kWh need applies to any brand.

More from Sun Connect Solar

Home batteries by town

Prices are the same across the Northern Rivers: we install the same way everywhere, to Australian standards, and the $500 Northern Rivers locals discount is already in every figure. See what homes near you have installed and the local detail for your area: Mullumbimby, Byron Bay, Ballina, Lennox Head, Lismore, Goonellabah, Alstonville and Wollongbar, Bangalow, Ocean Shores, Brunswick Heads, Suffolk Park, Murwillumbah, Pottsville, Tweed Heads and Kingscliff, Banora Point, Bilambil Heights, Coraki and Woodburn, Evans Head. Or browse our install map by town and recent installs and case studies.

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