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Is solar worth it in South Australia? Payback for 2026–27

Typical 6.6 kW system · Adelaide (STC Zone 3)

4.0 years payback on a $6,500 post-STC quote

Annual benefit ≈ $1,640 ($1,531 bill savings + $110 exports) · 10-year position ≈ $9,901.

Every assumption below is a dataset value — change any of them in the calculator.

Solar payback calculator

SA

6.6 kW is the most common residential size.

Pre-set: Deregulated — retailers set their own rate.

4.0 years estimated payback
Annual generation (3.79 kWh/kW/day, STC Zone 3)
9,130 kWh
Bill savings (self-consumed at 41.9c/kWh)
$1,531/yr
Export earnings (2.0c/kWh feed-in)
$110/yr
Total annual benefit
$1,640/yr
Net cost
$6,500
10-year position
$9,901

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, SA 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 →

SA payback against the other states

  • At 4.0 years, South Australia ranks 2nd fastest of 8 states on these defaults; the Northern Territory is quickest at 3.5 years and Victoria slowest at 5.7 years.
  • Using 60% of the output at home, the same system pays back in 2.7 years, compared with 4.0 years at 40% and 7.1 years at 20%.
  • Exports earn $110 a year here, 6.7% of the benefit; the power you don't buy is worth 14 times as much.

The assumptions, sourced

Default assumptions for the SA payback figure
InputValueSource
Daily generation per kW3.79 kWhCER zone rating, derived (Zone 3)
Usage tariff offset41.9c/kWhAER Default Market Offer 2026–27 (DMO 8) (SA Power Networks)
Feed-in tariff2.0c/kWhRetailer survey median, 17 October 2026
Self-consumption40%Editable assumption (typical daytime-home share)
STC value$1,79645 STCs × $40 spot (10 July 2026)
Price basispost-STCAU quotes include the STC discount — not subtracted again

How the numbers are built

Generation = kW × the CER-derived daily factor × 365. The share you use directly offsets power at your usage rate; the rest exports at the feed-in rate. Net cost is your quote minus any upfront state rebate — and minus the STC value only if your quote was genuinely pre-STC, which Australian quotes almost never are. Payback = net cost ÷ annual benefit. Full formulas on the methodology page.

Frequently asked questions

How many years to pay back solar in SA?
About 4.0 years for a typical 6.6 kW system quoted at $6,500 (a post-STC price), self-consuming 40% — an annual benefit of ≈$1,640. Your roof, usage pattern and quote move it; change every input in the calculator above.
How is the STC rebate worked out?
kW × zone rating (1.382 in Adelaide, Zone 3) × deeming years (5 for a 2026 install), rounded down, × the certificate price ($40). For this system that's 45 STCs ≈ $1,796 — already inside a normal Australian quote, which is why the calculator doesn't subtract it again by default. Full detail: SA solar rebates.
Does the feed-in tariff still make solar worth it?
The FiT is no longer the engine — at 2.0c/kWh, exports earn ≈$110/yr here versus ≈$1,531/yr from self-consumption at 41.9c/kWh. Payback now lives on the power you don't buy, not the power you sell. See SA FiT rates.
Is a battery worth adding?
A battery converts low-value exports into high-value self-consumption, and the federal Cheaper Home Batteries Program discounts a VPP-capable battery via STCs (roughly a third off). It lengthens the combined payback versus panels alone in most homes, but the gap has narrowed — the case is strongest where the FiT is lowest. Scheme detail: SA rebates.

Related

Sources — figures current as at 17 July 2026.

Panel degradation, tariff escalation, financing costs and export limits are excluded — the estimate is conservative on generation (CER-deemed factor) and neutral on prices. Not solar-purchase advice.