A system sized to that bill
| System size | 3.6 kW, to cover a $180/month bill |
|---|---|
| Before rebate | $3,645 at $1.00/W |
| STC rebate | −$950 (25 certificates) |
| You pay | $2,695 |
| Generates | 5,037 kWh a year |
| Saves in year one | $909 |
| Pays for itself in | 2.9 years |
| Over 25 years | $26,386 net |
Assumes a $180/month bill and that you use about 40% of what you generate as you generate it — the rest is exported at 1.5c. A battery shifts that balance, and in South Australia it shifts it a long way.
Median of current single-rate residential offers and feed-in tariffs, Australian Energy Regulator — Consumer Data Right, Product Reference Data, as at 2026-08-23
Why the rebate shrinks every January
25 certificates at $38 each — 3.6 kW × 1.382 zone rating × 5 years deeming. The scheme closes at the end of 2030, so the deeming period — and the rebate — shrinks every January. Certificate price is market-set and assumed conservatively below the $40 Clearing House ceiling. Installing a year later on the same system costs you roughly $190 in lost rebate.
Computed at build time from the SRES deeming rule · certificates assumed at $38, below the $40 Clearing House ceiling
No regulator has set a minimum here since 2017
South Australia’s Retailer Feed-in Tariff scheme has had no mandated minimum since 1 January 2017, when the Essential Services Commission of South Australia determined it would stop setting one. Each retailer decides its own rate and structure, and is required to demonstrate publicly how its offer delivers a benefit to solar customers — a transparency obligation rather than a price floor. Combined with the highest retail prices in the country, this produces the widest gap of the six states between what a kilowatt-hour costs to buy and what it earns to sell: about 3% of retail.
Sources: ESCOSA — solar feed-in tariff scheme · SA Government — solar feed-in payments
What's different about South Australia
Your postcode may be worth more than the capital
South Australia spans STC zones 1, 2, 3. This page uses Adelaide's rating of 1.382, because that is where most of the population is — but a system in zone 1 is rated 1.622, about 17% higher. That lifts both the power a system makes and the number of certificates it earns, so a regional install is cheaper and more productive than the figures here suggest.
The smallest set of offers of the six
30 residential offers from 9 retailers — fewer than any other state on the national market, and about a fifth of what a household in the biggest market can choose between. A thinner market means less room to save by switching, which shifts more of the case onto generating your own.
Exports are worth less here than anywhere else
At 4% of retail, a kilowatt-hour sold back is worth about a thirtieth of one you use yourself. Sizing a system to sell power is close to giving it away; sizing it to your own daytime load is the whole game.
The dearest power in the country
Nowhere on the national market pays more per kilowatt-hour, which is why payback here is the fastest of the six despite the sunshine being unremarkable. Expensive power makes solar pay, more than sunshine does.
The market here
These figures are medians across 18 single-rate residential offers from 9 retailers, with 12 time-of-use offers set aside as not comparable. Adelaide sits in STC zone 3 — though South Australia spans zones 1 and 2 and 3, and this page uses the capital's.
The retailers whose current offers feed these figures are AGL, Diamond Energy, Lumo Energy (SA), Momentum Energy, Origin Energy, Powershop, Red Energy, Tango Energy and iO Energy. That is who is actually selling power to households here this week — not a list of every licensed retailer, and not the same list as the state next door.
The honest verdict on South Australia
The fastest payback of the six states, and for a reason worth being clear about: it is not the sunshine, it is the price of the power you stop buying. South Australians pay more per kilowatt-hour than anyone else on the national market, which makes every unit of self-consumed solar unusually valuable — while the same economics make exporting close to pointless. This is the state where a battery, or simply shifting load into the middle of the day, changes the arithmetic most.
The other states
Compare every state side by side →
Where these numbers come from
- Power price — Median usage rate across 18 single-rate residential market offers from 9 retailers. Time-of-use offers are excluded — they are not comparable to a flat rate without a household load profile. (measured, as at 2026-08-23)
- Feed-in tariff — Median flat solar feed-in rate across 32 residential market offers. Time-varying feed-in tariffs are excluded. (measured, as at 2026-08-23)
- Solar yield — Clean Energy Regulator STC zone 3 rating (1.382 MWh/kW/yr) for Adelaide, postcode 5000. A deemed radiation-based figure used to calculate certificate entitlements, not a measured or simulated output. This state spans zones 1 and 2 and 3; the capital's zone is published because that is where the population is. (modelled, as at 2020-01-01)
How every one of these numbers is worked out →
Sources: Australian Energy Regulator — Consumer Data Right, Product Reference Data, Clean Energy Regulator — postcode zone ratings for solar PV systems.