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Solar Lease vs Buy Calculator (Australia)

Free Australian solar lease vs buy calculator. Compare cash, financed, and PPA / SunSaver-style structures over 25 years using current 2026 STC rebates, CEC-aligned pricing, and AER feed-in tariff data.

Solar Lease vs Buy Calculator

Cash purchase — 25-year net
$108,778
Loan purchase — 25-year net
$106,531
PPA — 25-year net
$24,772
Verdict
Cash purchase wins by $2,246

How to use this calculator

Enter your gross system cost, year-1 monthly bill savings (self-consumption + state feed-in tariff income), STC rebate as a percentage of gross cost, and the financing parameters. The calculator returns your 25-year net position for cash purchase, financed purchase, and PPA — and highlights the winner.

The math accounts for the federal STC rebate (claimed only by the owner / passed via the CEC-approved retailer), AER tariff escalation (default 3.5%/yr — AER 2026 outlook), 0.5% annual O&M, and a 7%-of-system-cost inverter replacement at year 12.

How the math works

Three side-by-side 25-year cash flow models:

Cash purchase

net = -systemCost + STC + Σ(yr 1..25) annualSavings × (1 + esc)^(y-1)
      − O&M − inverter

Loan purchase (Brighte, Plenti, credit-union green)

monthly = P × r / (1 − (1+r)^-n)
net = -totalLoanPaid + STC + Σ savings − O&M − inverter

PPA

net = Σ savings − Σ leasePayment × (1 + leaseEsc)^(y-1)

Worked example for the en-au defaults ($7,800 system, 28% STC = $2,184, $248/mo savings, 7.49% / 7-yr loan, $195/mo PPA at 3.5% escalator, 3.5% rate escalator, 25-yr horizon):

  • Cumulative bill savings (3.5%/yr escalation): $2,976 × ((1.035²⁵ − 1) / 0.035) ≈ $115,907
  • Cash net: −$7,800 + $2,184 + $115,907 − $975 O&M − $546 inverter = +$108,770
  • Loan total paid: $122.30 × 84 = $10,273; net = −$10,273 + $2,184 + $115,907 − $975 − $546 = +$106,297
  • PPA cumulative payments (3.5% escalator over 25 yrs): $2,340 × 38.95 ≈ $91,143; PPA net = $115,907 − $91,143 = +$24,764

Cash beats PPA by ~$84,000 over 25 years. Cash beats loan by ~$2,500. Australia’s combination of high tariffs, high irradiance, and STC rebate makes ownership overwhelmingly superior.

Why Australian leases lose so badly

Australia is the country where leasing makes least sense:

  • STC rebate (~$700/kW Zone 3 in 2026) goes to the owner, not the lessee
  • State feed-in tariffs (NSW/QLD/SA/WA) flow to the registered meter owner, not the lessee
  • High retail rates ($0.28-$0.45/kWh nationally) mean self-consumption savings are large
  • Short payback (3-5 yrs cash) means the asset is paid back well before any 7-year PPA term ends
  • Mature loan market (Brighte 5.49-7.99%, Plenti 5.99-8.99%, RateSetter 6.5-9.5%) means $0-down owner-financed alternatives exist

The PPA only makes sense in cases where the homeowner has zero credit (cannot finance) AND zero cash (cannot buy outright) AND does not plan to move within 7 years.

Lease vs buy: side-by-side reality

FactorCashLoanPPA
Up-front cost$7,800$0-$200 dealer$0
Monthly cash flow year 1+$248+$126+$53
25-year net+$108,770+$106,297+$24,764
STC rebate ($2,184)HomeownerHomeownerOperator
State FiT incomeHomeownerHomeownerOperator
Equity in system100%100% (after loan)0%
Resale value premium$5k-$10k typicalSame as cash$0 (often a barrier)
Inverter replacementHomeownerHomeownerOperator
Annual escalatorNoneNone2.5-3.5% per year

Pair this with the solar loan calculator, payback calculator, and ROI calculator

The Australian residential solar question is essentially “cash or loan.” Run the loan calculator to size monthly repayments at Brighte/Plenti rates, the payback calculator to confirm 3-5 year break-even, and the ROI calculator to validate 25-year IRR (typically 15-22% in Australia — among the world’s highest).

Sources

Frequently asked questions

Are solar PPAs available in Australia in 2026?
Yes, but limited and shrinking. SunEdison's Australian PPA arm exited in 2018; the current market is dominated by SunSaver (Brisbane, Sydney), Smart Energy Group, and small operators like Solar Choice's PPA referrals. Most quotes are 7-10 year PPAs at $0.18-$0.28/kWh consumed, escalating 2.5-3.5%/yr. Outside major cities, the network is sparse — Adelaide, Hobart, Darwin, and most regional NSW/Vic have effectively no PPA market. Owner-financed installations through Brighte, Plenti, RateSetter, and credit-union green loans now dominate (Clean Energy Council 2025 data: 88% owner-financed, 9% cash, 3% PPA).
Should I buy or lease solar in Australia?
Buy. Australia has the world's most generous residential solar economics — high irradiance (4-5.5 sun-hours nationwide), high retail rates ($0.28-$0.45/kWh), and the federal STC rebate that knocks 20-30% off gross cost. A typical 6.6 kW system costs $7,000-$8,500 net of STCs and pays back in 3-5 years for cash buyers. PPAs effectively erase the STC benefit (the operator captures it), the feed-in tariff (operator captures), and the asset value at end of contract. Over 25 years, cash beats PPA by $30,000-$50,000 in most state markets.
Does the STC rebate apply to leased systems?
Technically yes — the STCs are claimed at point of installation regardless of who owns the asset. But in a PPA structure, the third-party operator captures the STC value through the gross system price reduction and prices the lease accordingly. The homeowner sees no direct STC benefit. In an owner-financed installation, the homeowner sees the STC discount on the invoice from the CEC-approved retailer (typically $2,000-$3,000 off a 6.6 kW system depending on Zone 1-4 location).
What state feed-in tariffs am I forfeiting if I lease?
All of them. Feed-in tariffs flow to the registered owner of the asset on the meter agreement: NSW ($0.05-$0.12/kWh under DMOs and retailers like AGL, Origin, Energy Australia), Victoria ($0.04-$0.08/kWh under VDO), Queensland (Regional Cap $0.10-$0.13/kWh, SE QLD market-driven $0.06-$0.10), SA ($0.04-$0.10/kWh), WA Synergy DEBS ($0.025-$0.10), Tas ($0.084 Aurora), NT ($0.083-$0.27 PWC). For a 6.6 kW system exporting 6,000 kWh/yr at $0.07 average, that's $420/yr — over 25 years, $14,500 (no escalation) that the operator captures, not you.
What about commercial solar PPAs?
Different market. Commercial PPAs (10-100 kW+, retail/industrial sites) are more competitive in Australia because the operator can claim the LGC certificates plus depreciate the asset under Division 40 of the Tax Act. For a residential homeowner, commercial PPA pricing doesn't apply — and the residential PPA market is too thin to drive operator competition. The 2026 verdict: residential = own; commercial = run the model both ways.

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