Price your system
Pick a system size, add your postcode (or a state if you don't know your postcode's zone) and your quarterly bill. Toggle in a 13.5 kWh battery to price the two together. Every figure below updates instantly using the same maths as the rest of this page.
STC deeming drops from 5 to 4 years on 1 January 2027. The same 6.6 kW system gets $357 less.
Estimates, not a quote. Savings are shown ±10% to allow for your roof, retailer plan and hardware choice, and payback counts bill savings only: VPP credits from a battery would be extra. Assumptions: Sydney (STC zone 3), a $450 quarterly bill, grid power at 32c/kWh, 1,450 kWh a year per kW, price after the federal rebate only, bill savings only (no VPP income), savings ±10%. Installed prices come from the Solar Choice Price Index, October 2026, checked 10 October 2026. The STC rebate is a point-of-sale discount your installer applies to the invoice, valued at the spot price ($39.65/certificate) for a 2026 install; it isn't a cheque you receive afterwards. Rebate figures verified 13 July 2026 against the Clean Energy Regulator and DCCEEW.
How this calculator works
The "before rebate" price comes straight from our system-size price table. Per-kW band of $1,050 to $1,390 before rebates: the cheapest (Perth 7 kW) and dearest (Hobart 6 kW) capital-city prices at 6 to 10 kW in the index, Darwin excluded, with each city's STC discount added back. Sizes above 10 kW are scaled at the same per-kW rates; smaller systems usually cost more per kW. The federal STC rebate is your STC zone rating × system size (kW) × 5 deeming years for a 2026 install, floored to a whole certificate, valued at $39.65 each; Zone 3 (Sydney, Brisbane, Adelaide, Perth, Canberra) earns fewer certificates than Zone 1 or 2, and Zone 4 (Melbourne, Hobart) fewer still. Add a battery and the same maths runs again on a 13.5 kWh battery against the federal Cheaper Home Batteries factor, currently worth $3,608 off a $14,106-$16,206 installed battery. The annual saving and payback, shown as a band rather than one number, come from the same savings engine behind every other calculator on this site, not a separate estimate. Payback counts bill savings only; VPP credits from a battery would be extra. The bill starts at the typical bill for the size you pick, the same bill each size page computes its payback at, until you move it.
Every assumption the savings engine makes
- Grid power at 32c/kWh; about $400/yr of supply charges that solar can't offset
- Solar yield 1,450 kWh per kW per year (national average); each generated kWh valued at about 15c blended (self-use plus export); solar alone offsets at most 60% of the bill
- Battery cycles about 80% of its capacity daily at the evening spread (32c grid vs 5c feed-in), calibrated to the government's up-to-$1,100/yr estimate for 13.5 kWh; solar plus battery offsets at most 90% of the bill
- Payback counts bill savings only. VPP credits (assumed $250/yr, the low end of the typical $200-$500/yr) are shown separately
- Solar priced from the Solar Choice Price Index, October 2026 (checked 10 October 2026): $1,050-$1,390 per kW before rebates, midpoint used
- Battery priced at the midpoint of its installed band in the site's battery price table (/solar-battery-prices/, prices as of 10 October 2026), less the federal rebate
- STCs valued at $39.65 each; installer pass-through is typically $37-$40
- Estimates only, general information and not financial advice. Your quote depends on your roof, retailer plan and hardware choice.
Installed price by system size (Zone 3, 2026)
Computed for Sydney, Brisbane, Adelaide, Perth and Canberra (STC Zone 3). Melbourne and Hobart (Zone 4) earn a smaller STC rebate on the same system. Zones are set per postcode, not per state, so a regional address can sit a zone above or below its capital. The calculator above reads your postcode's own zone straight from the Clean Energy Regulator's postcode table and prices the STC line from that.
| System size | Before rebate | STCs | STC rebate | After STCs | Payback (bill) |
|---|---|---|---|---|---|
| 5 kW | $5,300-$7,000 | 34 | $1,348 | $3,952-$5,652 | 6.0 to 10.5 years ($250/qtr) |
| 6 kW | $6,300-$8,300 | 41 | $1,626 | $4,674-$6,674 | 4.7 to 8.2 years ($375/qtr) |
| 6.6 kW | $6,900-$9,200 | 45 | $1,784 | $5,116-$7,416 | 4.3 to 7.6 years ($450/qtr) |
| 8 kW | $8,400-$11,100 | 55 | $2,181 | $6,219-$8,919 | 3.6 to 6.4 years ($650/qtr) |
| 10 kW | $10,500-$13,900 | 69 | $2,736 | $7,764-$11,164 | 3.5 to 6.1 years ($850/qtr) |
| 13.2 kW | $13,900-$18,300 | 91 | $3,608 | $10,292-$14,692 | 4.3 to 7.6 years ($900/qtr) |
| 15 kW | $15,800-$20,900 | 103 | $4,084 | $11,716-$16,816 | 4.4 to 7.8 years ($1,000/qtr) |
| 20 kW | $21,000-$27,800 | 138 | $5,472 | $15,528-$22,328 | 4.2 to 7.4 years ($1,400/qtr) |
Common questions
How do I calculate how much solar I need?
Match your quarterly power bill to a system size: Under $300 / quarter → 5 kW; $250-$500 / quarter → 6 kW; $300-$600 / quarter → 6.6 kW; $500-$800 / quarter → 8 kW; $700-$1,000 / quarter → 10 kW; $900+ / quarter → 13.2 kW; $1,000+ / quarter → 15 kW; $1,400+ / quarter → 20 kW. That's a starting point, not a design; roof space, orientation and shading also matter. The calculator above uses the same size-by-bill logic to preselect a system and shows the exact price, STC count and payback for your postcode once you enter it.
Will a 10kW solar system run a house?
A 10 kW system generates about 14,500 kWh a year (roughly 40 kWh a day, averaged across the seasons), which suits 4-6 people on a $700-$1,000 / quarter bill. It comfortably covers daytime loads and, paired with a 13.5 kWh battery, most evening use too. On its own, without a battery, it still can't run the house after dark, since panels only generate while the sun is up.
How much should a 6.6 kW solar system cost?
$6,900-$9,200 installed before any rebate. After the federal STC rebate (45 certificates for a 2026 install in Zone 3 cities: Sydney, Brisbane, Adelaide, Perth and Canberra) that drops to about $5,116-$7,416. Melbourne and Hobart sit a little higher, since they're Zone 4 and earn fewer certificates for the same system. Use the calculator above for the exact band on your own postcode.
How long does solar take to pay for itself?
On this calculator's defaults, a 6.6 kW system in Sydney pays back in about 4.3 to 7.6 years on a $450 quarterly bill, counting bill savings only. Change the bill, size or postcode above and the band moves with them. The assumptions: Sydney (STC zone 3), a $450 quarterly bill, grid power at 32c/kWh, 1,450 kWh a year per kW, price after the federal rebate only, bill savings only (no VPP income), savings ±10%.
Is there a solar calculator for Australia?
Yes, the calculator on this page. It computes an installed price band after the federal STC rebate, the STC count, a 13.5 kWh battery add-on after its own federal rebate, and an estimated annual saving and payback band, all from the Clean Energy Regulator and DCCEEW formulas used across this site. For the battery rebate on its own (no new panels), use the battery rebate calculator; for the STC formula by itself, see the STC rebate calculator.