The maths on rooftop solar in Australia has changed twice in the past decade. The first shift was the collapse of the generous early feed-in tariffs that made systems pay back in three or four years. The second was the steady rise in retail electricity prices that, by 2025–26, has made self-consumption the dominant driver of payback.
For most Australian households in 2026, the answer is still yes — but for very different reasons than ten years ago.
The 2026 numbers, in plain terms
A typical 6.6 kW residential solar system in Australia costs around $7,500–$10,000 installed after Small-scale Technology Certificates (STCs) have been netted off. On an unshaded north-facing roof in a capital city, it generates roughly 9,600 kWh per year in year one — falling slightly each year as panels degrade.
Two prices matter for the payback maths:
- Retail rate — what you pay for grid electricity. Default Market Offer rates published by the Australian Energy Regulator sit around 28–35 c/kWh in 2025–26 depending on the state.
- Feed-in tariff — what your retailer pays you for solar exported back to the grid. National averages have fallen to 4–7 c/kWh, with some retailers offering as low as 3 c/kWh.
That five- to seven-fold gap is the entire game. Every kWh you self-consume saves you the retail rate. Every kWh you export earns you the feed-in tariff. Solar pays back fastest for households that use power during daylight hours.
Worked example: a typical Sydney family
Take a household using 20 kWh/day, with a $8,000 6.6 kW system, 30% self-consumption, 30 c/kWh retail rate and 5 c/kWh feed-in tariff. Plug those into the solar payback calculator and you get:
- Year-one savings: about $1,200
- Payback period: just under 7 years
- 25-year net benefit: around $20,000 in today's dollars
That's a system that more than doubles your money over its life — even before factoring in the near-certainty of further electricity-price increases.
The single lever that changes everything
Self-consumption percentage is the most powerful input in the model. The same household above, but with 60% self-consumption (a battery, an EV charger, a daytime hot-water timer or a pool pump), sees:
- Year-one savings: roughly $1,900
- Payback: under 5 years
- 25-year net benefit: about $35,000
Conversely, a household away from home all day with 15% self-consumption struggles to pay back a typical system in under 11 years. That doesn't make solar pointless — it just changes how you should size and design the system.
What about batteries?
A home battery is essentially a tool for buying back self-consumption. It stores midday solar export and discharges it during the evening peak, replacing grid imports at the retail rate.
At 2025–26 installed prices (around $1,000–$1,400 per usable kWh of capacity), batteries typically add 4–7 years to a solar system's payback. They make better economic sense when:
- You're on a time-of-use plan with a high evening peak rate.
- Your feed-in tariff is very low or capped at a small daily volume.
- You want backup during outages — though most basic battery installs don't include this without an extra hardware module.
What about east/west or south-facing roofs?
Orientation matters less than people fear. A north-facing array is the gold standard, but east/west panels generate around 88% of north's annual yield, and the production curve is flatter — meaning more generation in the morning and afternoon, when most households actually use power. South-facing arrays drop to about 72% of north's yield and are usually worth modelling carefully before committing.
What about retail-rate inflation?
The 25-year payback model in the Wattcalc calculator deliberately keeps electricity prices constant. This is a conservative choice — the AER's published Default Market Offer has risen by between 6% and 25% across the last three review cycles depending on the state, and most independent forecasters expect modest annual increases through the rest of the decade. Every 1% real-terms rise in retail rates compounds: across a 25-year system life, even a 2% annual real rise lifts net lifetime savings by roughly 25–30% over the constant-rate baseline.
If you want to model that explicitly, the simplest approach is to enter a slightly higher retail rate than today's actual figure — say, the rate you reasonably expect to be paying in 5 years' time. The result is a closer approximation of what your average payback period will actually look like.
The role of state and federal incentives
The biggest single subsidy on a residential solar install is the federal Small-scale Technology Certificate (STC) scheme, which is netted off the system cost by every accredited installer at the point of sale. There is no separate rebate to apply for — the system you're quoted has the discount built in. STCs are scheduled to phase out by 2030, with the value reducing each year, so timing matters at the margin.
Beyond STCs, several states currently run battery rebates (NSW, Victoria, WA), interest-free loans (Victoria, ACT) and feed-in tariff bonuses for specific cohorts. State scheme details change frequently — check your state energy department's website before assuming any incentive applies, and always confirm the after-rebate price in writing with your installer.
Is solar still worth it in 2026? The verdict
For households with average or above-average daytime usage, on a typical retail tariff, on a north or east/west roof: yes, in almost every case. Payback periods of 5–8 years and 25-year net returns of $15,000–$40,000 are routine. Use the solar payback calculator to model your own numbers, and get at least three quotes from Clean Energy Council-accredited installers before signing.
For households away from home all day with low self-consumption, the answer is more nuanced. A smaller system sized to actual daytime usage, or a small system plus a hot-water diverter, often beats a maximum-size install in pure payback terms. The wrong question is "what's the biggest system my roof will fit?" — the right one is "what's the largest system whose generation I'll actually use myself, plus a small export buffer?"
For more on the household side of the equation, see our guide on how to reduce your electricity bill in Australia in 2025–26. To compare an EV against a petrol car — and how rooftop solar changes the EV running cost — try the EV vs petrol calculator.
Sources
- Australian Energy Regulator — Default Market Offer 2025–26.
- ARENA — residential solar performance assumptions.
- Clean Energy Council — installer accreditation and consumer guidance.