Solar Payback Calculator Australia (2026)

How solar payback works in Australia in 2026

Solar payback is the simplest honest measure of whether rooftop solar is worth it: the number of years it takes for the money a system saves to add up to what you paid for it. The calculation is deliberately plain — net cost divided by annual savings — but every input behind those two numbers has shifted over the last two years, which is why a payback figure quoted in 2023 is usually wrong today.

The biggest shift is structural. Until recently, a lot of a solar system's value came from exporting surplus power to the grid and being paid a generous feed-in tariff. That era is over. Across the country, feed-in tariffs have collapsed toward a few cents per kWh, and in some states they sit near zero in the middle of the day when solar floods the grid. Victoria removed its mandated minimum feed-in tariff on 1 July 2025; South Australia never mandated one and now applies "solar sponge" pricing that can even charge for midday exports. The practical consequence is that payback in 2026 is self-consumption-dominant: the value is in the power you generate and use yourself, because every self-consumed kilowatt-hour avoids buying that same energy from your retailer at the full retail price.

That makes retail electricity prices the real engine of payback. South Australia and Western Australia have the highest retail tariffs in the country — around 32 to 34 cents per kilowatt-hour — so every unit of solar you consume on-site is worth more there than anywhere else. Queensland and Victoria sit lower. This is why the same 6.6 kW system can pay back in under three years in Adelaide and take well over four years in Melbourne, even though the panels are identical. The hardware is a commodity; the savings are local.

What four inputs decide your solar payback?

Your payback number is decided by four inputs — net cost, annual generation, self-consumption share and feed-in tariff — and the third one matters most:

1. Net cost. This is the install price minus the federal STC rebate (explained below). Installed prices in 2026 are remarkably low by historical standards — roughly $0.88 to $1.05 per watt fully installed across the mainland capitals — so a quality 6.6 kW system typically lands around $5,000 to $7,000 after the rebate. A cheaper quote shortens payback, but the lowest quote is not always the best value once you account for panel and inverter quality and warranty support.
2. Annual generation. How much energy your system makes depends on sunlight, which varies by location. Perth and Brisbane are the sunniest capitals, producing roughly 1,600 to 1,700 kilowatt-hours per installed kilowatt each year; Melbourne is the lowest among the mainland capitals at around 1,350. A bigger system generates more, but only pays back faster if you can actually use or sell the extra output.
3. Self-consumption share. This is the single most powerful lever in the whole calculation, and the one most calculators hide. If you are home during the day, run appliances on a timer, or have a pool pump or electric hot water, you might self-consume 50 to 70 percent of your generation. If the house is empty until evening, it could be 20 to 30 percent. Because self-consumed power is worth four to ten times more than exported power in 2026, raising your self-consumption from 30 to 60 percent can cut a year or more off your payback without spending a dollar more on hardware.
4. Feed-in tariff. Exported power still earns something — typically 3 to 8 cents per kilowatt-hour depending on your state and retailer — but it is now a minor contributor for most households. It matters most for large systems on homes with low daytime usage, where a big share of generation is exported by necessity.

What is the STC solar rebate and how is it calculated?

The STC rebate is the federal upfront discount on your solar system, set by the Small-scale Renewable Energy Scheme (SRES), which gives every eligible solar installation a set of small-scale technology certificates (STCs); your installer almost always claims them on your behalf as an upfront discount. You rarely see the certificates themselves; you see a lower price. The value is calculated as:

System size (kW) × zone rating × deeming years × STC price.

For a mainland capital the zone rating is 1.382. The deeming period — the number of future years of generation the scheme credits you for upfront — is 5 years for any system installed in 2026, and it drops by one year every 1 January (to 4 years in 2027, 3 in 2028, and so on) as the scheme winds down toward its legislated end on 31 December 2030. The STC price hovers near the $40 clearing-house cap, around $39.50 after trading fees. Put together, a 6.6 kW system in 2026 earns about 46 certificates — roughly $1,800 off the price. Because the deeming period shrinks each year, the same system bought a year later receives a smaller rebate, which is a genuine reason not to wait if you have already decided to install.

Does a home battery improve solar payback in 2026?

A battery improves payback only indirectly, and usually lengthens it, so most people add one for resilience rather than the fastest return. From 1 May 2026 the federal Cheaper Home Batteries program discounts home batteries by about $252 per usable kilowatt-hour at the full rate for the first 14 kWh, stepping down every six months until 2030. The benefit is real: a battery lets you store cheap daytime solar and use it at night instead of exporting it for a few cents and buying it back at full price. That arbitrage works, but battery hardware still costs roughly $1,000 per usable kilowatt-hour, so a battery usually lengthens overall payback compared with panels alone. Most people who add one do so for evening bill coverage, blackout resilience and price certainty rather than the fastest possible return — and this calculator lets you toggle a battery on to see exactly what it does to your numbers.

Solar payback by state — 2026 snapshot

The table below shows the indicative defaults this calculator uses for each state. Typical payback assumes a 6.6 kW system at 60% self-consumption. Open a state page for the local detail, rebates and a state-specific calculator.

Methodology & sources

Data last verified: 27 June 2026

This calculator uses the self-consumption-dominant model that reflects 2026 conditions. The formula is:

• STC rebate = system kW × zone rating (1.382) × deeming years (5) × STC price ($39.50)
• Net cost = system kW × install $/kW (your after-STC price); a battery adds its capex net of the Cheaper Home Batteries rebate
• Annual generation = system kW × generation per kW per year
• Annual savings = self-used kWh × power price + exported kWh × feed-in tariff (+ battery arbitrage value)
• Payback = net cost ÷ annual savings

Solar payback period

The number of years it takes for a system's accumulated savings to equal its net cost after rebates. Net cost ÷ annual savings.

Self-consumption

The share of the electricity your panels generate that you use on-site rather than export to the grid. The biggest single lever on payback in 2026, because self-used power is worth the full retail tariff.

STC rebate

The upfront discount from the federal Small-scale Renewable Energy Scheme, delivered as small-scale technology certificates your installer claims for you.

Deeming period

The number of future years of generation the STC scheme credits you for upfront — 5 years in 2026, falling by one each 1 January until the scheme ends in 2030.

Feed-in tariff (FiT)

The rate your retailer pays for surplus solar you export to the grid. Now a minor contributor for most households as rates have fallen toward zero.

Worked example (South Australia default): 6.6 kW × 1.382 × 5 × $39.50 ≈ $1,801 rebate. Generation ≈ 6.6 × 1,550 = 10,230 kWh/yr. At 60% self-use and 34c/kWh, plus 40% export at 4c, annual savings ≈ $2,251. Net cost ≈ $6,270 → payback ≈ 2.8 years.

Sources

• STC price & deeming — Clean Energy Regulator (clearing-house $40 ex-GST; deeming 5 yr in 2026), pulled 2026-06-27.
• Install prices — SolarChoice Price Index, June 2026.
• Electricity prices — Canstar average price per kWh by state.
• Feed-in tariffs — Solar feed-in tariffs by state, 2026; IPART (NSW), Essential Services Commission (VIC).
• Generation yield — SolarChoice / Bureau of Meteorology peak-sun-hours.
• Battery rebate — DCCEEW Cheaper Home Batteries Program (~$252/kWh from 1 May 2026).

We re-check these figures on a regular schedule and update the verified date only when a value genuinely changes. Estimate only — not financial advice.