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Solar Investment Tax Credit Calculator (Australia)

Free commercial solar investment tax credit calculator for Australian businesses. Estimate STC point-of-sale discount, Instant Asset Write-Off, Division 40 depreciation, and net cost after every business incentive.

Prepared by the Solar Calculator HQ editorial team. Review our formula, source and limitation standards.

Solar Investment Tax Credit Calculator

Gross cost
$110,000
Total incentive
$39,500
Investment credit value: $0
Tax-deduction shield: $27,500
STC + rebate value: $12,000
Net cost after rebate
$70,500
Effective discount
35.9%
Strong rebate — STC + Instant Asset Write-Off

How to use this calculator

The calculator above stacks the STC point-of-sale discount, Instant Asset Write-Off or Division 40 depreciation tax shield, and any state grant into a single net-cost number for Australian commercial buyers:

  1. Gross system cost — total quoted price by the Clean Energy Council Approved Retailer/Installer for commercial PV. CEC’s 2026 Industry Snapshot puts commercial rooftop at A$1.10–A$1.40/W installed, so a typical 80 kW commercial rooftop project runs A$95,000–A$115,000.
  2. Investment credit (% of cost) — usually 0; Australia has no federal commercial ITC. Enter a non-zero value only if your industry has a specific instant write-off pilot.
  3. Instant write-off / Div 40 deduction — A$20,000 IAWO × 25% small-co corporate rate = A$5,000 immediate; OR Division 40 PV at ~25% × cost over the effective-life period.
  4. STC + state rebate — A$2,000 per STC × deemed STCs based on size and zone, plus state grants (VIC Solar Homes, ACT Sustainable Business, etc.).

How the math works

stc_value      = system_kW × deeming_period × zone_rating × stc_price
post_stc_basis = gross_cost - stc_value
deduction_pv   = depreciable_basis × corp_tax_rate × pv_factor
flat_grant     = state_program + utility_pbi
total_relief   = stc_value + deduction_pv + flat_grant
net_cost       = gross_cost - total_relief

A typical 50 kW commercial system in Victoria at A$60,000 with 25% small-business corporate rate, Division 40 effective-life depreciation, A$8,500 in STCs, and a A$3,500 Victorian state grant:

  • STC point-of-sale discount: A$8,500
  • Post-STC cost basis: A$60,000 − A$8,500 = A$51,500
  • Division 40 PV (25% × A$51,500 × 0.85 PV factor over effective life): A$10,944 PV
  • State grant: A$3,500
  • Total incentives: A$8,500 + A$10,944 + A$3,500 = A$22,944
  • Net cost: A$60,000 − A$22,944 = A$37,056 (38.2% effective discount)

STC zones, deeming, and STC market price (2026)

The Clean Energy Regulator’s STC scheme uses the system size in kW, postcode zone and the official deeming period—5 years for a 2026 solar-PV installation, then one year less annually through 2030:

ZoneCitiesRating
1Darwin, North Queensland1.622
2Brisbane, Sunshine Coast, Gold Coast1.536
3Sydney, Melbourne, Adelaide, Perth, Canberra1.382
4Hobart, Launceston1.185

STC count formula: system_kW × deeming_years × zone_rating. A 6.6 kW Melbourne system in 2026 (deeming 7 years, Zone 3 rating 1.382) earns 6.6 × 7 × 1.382 = ~64 STCs. At A$36/STC clearing price (Q1 2026), that’s A$2,304 in point-of-sale discount.

A 50 kW commercial system gets 50 × 7 × 1.382 = ~484 STCs ≈ A$17,400 — but anything above 100 kW switches to the LGC scheme (annual generation, ~A$30/MWh).

Division 40 effective-life table (TR 2024/3)

AssetEffective lifePrime cost rateDiminishing value rate
Solar PV array (modules + structures)20 years5%/year10%/year DV
Inverters10 years10%/year20%/year DV
Batteries (lithium)15 years6.67%/year13.34%/year DV
Monitoring / metering5 years20%/year40%/year DV

Diminishing value front-loads the deduction. For a A$60,000 system fully expensed under DV 10%: Year 1 A$6,000, Year 2 A$5,400, Year 3 A$4,860 — most of the present-value tax shield is captured in years 1–5.

Australian Energy Regulator Default Market Offer (2026)

The AER’s Default Market Offer (DMO) for FY 2025-26 sets reference prices for small business across distribution zones:

  • Ausgrid (Sydney): 32¢/kWh average
  • Energex (SE Queensland): 28¢/kWh
  • AusNet Services (Victoria): 31¢/kWh
  • SA Power Networks: 38¢/kWh
  • Western Power: 33¢/kWh

Commercial customers above the 100 MWh consumption threshold negotiate market contracts; AGL Business Solar Plus, Origin Solar Boost Business, EnergyAustralia GoSolar, Powershop SmartShift Business, Red Energy Solar Saver Business are common. Most include time-of-use export tariffs ranging 4¢–18¢/kWh feed-in.

State commercial program comparison (2026)

StateProgramCommercial value
VICSolar Homes business pilotA$3,500 cap, ≤30 kW
NSWEmpowering Homes commercial loanInterest-free to A$15,000
ACTSustainable Business Program50:50 grant to A$15,000
SARenewable Technology FundIndustrial case-by-case
QLDBattery Booster commercialA$3,000–A$4,000
TASEnergy Saver Loan SchemeInterest-free A$10,000
NTHome and Business Battery SchemeA$5,000–A$6,000

Worked example — 100 kW dairy farm in regional Victoria

  • Gross system cost: A$130,000 (A$1.30/W, CEC Approved Retailer)
  • STCs: 100 kW × 7 yrs × 1.382 (Zone 3) × A$36 = A$34,847 point-of-sale discount
  • Post-STC cost: A$95,153
  • Division 40 PV (25% small-business rate × 0.85 PV factor): A$20,220
  • VIC Solar Homes business pilot: A$3,500
  • Net cost: A$130,000 − A$34,847 − A$20,220 − A$3,500 = A$71,433
  • Effective discount: 45.1%

Pair this with the tax credit calculator, cost calculator, and payback calculator

The investment tax credit calculator gives the upfront net-cost; the payback calculator turns it into break-even years using your AER tariff or market-contract rate; the cost calculator benchmarks your gross.

Sources

Frequently asked questions

Does Australia have a federal solar Investment Tax Credit?
Australia has no headline federal Investment Tax Credit specifically for commercial solar PV. The closest equivalent is the Small-scale Technology Certificate (STC) scheme administered by the Clean Energy Regulator under the Renewable Energy (Electricity) Act 2000. STCs apply to systems up to 100 kW capacity, are deemed at install and traded at a market clearing price (~A$36 per STC in 2026), and reduce the contract price at point of sale through assignment to the installer. Larger systems (above 100 kW) instead earn Large-scale Generation Certificates (LGCs) on actual generation, sold annually into the LGC market (~A$30/MWh as of 2026 Q1 — well below the historical A$80–$110 peak).
What is the Instant Asset Write-Off and does it cover solar?
Yes. The Instant Asset Write-Off (IAWO) under Division 328-D of the Income Tax Assessment Act 1997 lets eligible small businesses (turnover <A$10 million) immediately deduct the cost of depreciating assets used in carrying on a business. The threshold for FY 2024-25 and FY 2025-26 is A$20,000 per asset (set by Treasury Laws Amendment Bill 2024). Solar PV systems and their components qualify as depreciating assets under §40-30 ITAA 1997, but the A$20,000 cap means most commercial solar projects (typically A$50,000–A$200,000) exceed the IAWO threshold and must use Division 40 effective-life depreciation instead.
How does Division 40 effective-life depreciation work for commercial solar?
Solar PV equipment falls under §40-95 ITAA 1997 with the Commissioner's effective life determination published in TR 2024/3 (formerly TR 2022/1). The effective life is 20 years for solar arrays, modules, and supporting structures, and 10 years for inverters. Businesses choose between the prime-cost method (straight-line, 5% annually for 20-year assets) or the diminishing-value method (200%/effective-life ≈ 10% per year applied to written-down value for 20-year assets). Diminishing value front-loads the deduction. Multiplied by the corporate rate of 30% (or 25% for base-rate entities below A$50m turnover in 2026), this produces an effective tax shield of 25–30% × the cost basis over the effective life.
Can I stack STCs with the Instant Asset Write-Off or Division 40 depreciation?
Yes — STCs reduce the contract price at the point of sale (the installer assigns them to themselves and discounts the quote), so the cost basis you depreciate under §40-180 ITAA 1997 is the post-STC net contract amount. For an A$110,000 commercial system that receives an A$12,000 STC discount, the cost basis for Division 40 is A$98,000. You then multiply by 25% (small-business corporate rate) × diminishing-value rate to get the year-1 deduction. The Cheaper Home Batteries Program (federal, started 1 July 2025) adds another A$370/kWh discount on home batteries — not commercial. Most state programs (VIC Solar Homes, NSW Empowering Homes, ACT Sustainable Business) target small business / residential.
What state-based programs stack with the federal STC scheme for commercial buyers?
State-based commercial solar programs in 2026 include: Victoria's Solar Homes business pilot (A$3,500 cap up to 30 kW); NSW Empowering Homes commercial loan (interest-free up to A$15,000 for SMEs); ACT Sustainable Business Program (matched grant 50:50 for small business energy efficiency / solar up to A$15,000); SA Renewable Technology Fund (case-by-case for industrial PV); Queensland Battery Booster commercial expansion (A$3,000–A$4,000 rebate); Tasmania Energy Saver Loan Scheme (interest-free A$10,000); Northern Territory Home and Business Battery Scheme (A$5,000–A$6,000 for businesses up to 50 kW PV+battery). Stacking rules vary — most state programs don't allow combining with another state grant on the same project but DO allow stacking with federal STCs and IAWO/Division 40 depreciation.

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