Solar payback calculator

Every input is a 2026–27 dataset value — your state's tariff, the surveyed feed-in rate, the CER generation factor and the STC value at the $40 spot of 10 July 2026. One trap this tool refuses to fall into: Australian quotes already include the STC discount, so it isn't subtracted twice.

Solar payback calculator

NSW

State

System size (kW)

6.6 kW is the most common residential size.

Quoted install price ($)

Feed-in tariff (c/kWh)

Pre-set: IPART benchmark (voluntary).

Install year

Self-consumption (power you use as it's made) 40%

Price already includes the STC discount (the normal Australian quote)

4.7 years estimated payback

Annual generation (3.79 kWh/kW/day, STC Zone 3): 9,130 kWh
Bill savings (self-consumed at 33.1c/kWh): $1,210/yr
Export earnings (3.0c/kWh feed-in): $164/yr
Total annual benefit: $1,375/yr
Net cost: $6,500
10-year position: $7,245

Your quote already includes ≈$1,796 of STC discount (45 STCs at $39.9 each) — it is not subtracted again.

Assumptions: CER-derived generation factor, NSW reference usage rate (AER Default Market Offer 2026–27 (DMO 8)), STC spot $39.9 as at 10 July 2026, deeming to the 2030 scheme end. Panel degradation, tariff changes and finance costs excluded. How these numbers are built →

The default case, state by state

On the defaults the NSW payback of 4.7 years ranks 5th fastest of 8 states; the Northern Territory is quickest at 3.5 years.
Raising self-consumption from 40% to 60% shortens the NSW payback to 3.4 years, compared with 7.9 years at 20%.

Reading the result

Payback is your net cost divided by the annual benefit — bill savings from the solar you use, plus export earnings on the rest. The state pages show the full assumptions table with each source: solar payback by state.

Sources — figures current as at 17 July 2026.

Not solar-purchase advice — confirm figures with accredited installers.