STC vs VEEC vs LGC: Which Fits Your Business?

In short: STCs are the federal upfront discount on solar up to 1 MW of site capacity for installs from 1 October 2026, 100 kW before (about $10,656 on a 50 kW Sydney system installed in 2027). VEECs are a Victoria-only upfront bonus for 30–200 kW systems (about $4,663 on a 50 kW metro Melbourne install) that stacks on top of the federal certificates. LGCs replace the upfront model on capacity above that ceiling with annual revenue per megawatt-hour generated (about $1,503 a year on 150 kW of Brisbane capacity above the ceiling at the $7 this site quotes with, the market less a 5% provider fee; LGC prices move, so treat it as a snapshot). Victoria between 30 and 200 kW is the richest combination; everywhere else it is STCs up to the ceiling and LGCs on the balance.

Australian businesses considering commercial solar face three distinct government incentive schemes: Small-scale Technology Certificates (STCs), Victorian Energy Efficiency Certificates (VEECs), and Large-scale Generation Certificates (LGCs). Each operates under different rules, covers different system sizes, and delivers value in fundamentally different ways. STCs provide a one-time upfront discount on solar up to 1 MW of site capacity for installs from 1 October 2026 (100 kW before). VEECs add a Victoria-only bonus for systems between 30 and 200 kW. LGCs generate ongoing annual revenue on capacity above that ceiling.

Understanding which schemes apply to your business, and whether they stack, is not academic. The difference between capturing all eligible incentives and missing one can shift a commercial solar payback period from three years to six. This guide breaks down each scheme with real numbers, worked examples, and the stacking rules you need to model accurately.

Quick comparison

STCs: the federal upfront discount

Small-scale Technology Certificates are the backbone of Australian solar incentives for solar up to 1 MW of site capacity installed from 1 October 2026 (100 kW before). Administered by the Clean Energy Regulator under the federal Renewable Energy Target, STCs represent the expected generation of a solar system over its remaining deeming period, which runs until 2030. In 2027, that means 4 years of deemed generation credited upfront at the point of installation. Systems between 100 kW and 1 MW installed from 1 October 2026 deem a fixed five years instead.

The number of certificates your system earns depends on three factors: system capacity in kilowatts, the STC zone multiplier for your location, and the remaining deeming period. Australia is divided into four STC zones based on solar irradiance. Zone 1 (far north Queensland, Northern Territory) carries the highest multiplier at 1.622. Zone 2 covers inland NSW and parts of central Australia at 1.536. Zone 3, which includes Sydney, Brisbane, Perth, and Adelaide, uses 1.382. Zone 4 (Melbourne, Hobart, and southern coastal areas) sits at 1.185.

Worked example: A 50 kW system installed in Sydney (Zone 3) in 2027 generates 50 × 1.382 × 4 = 276 STCs. At a net certificate price of $39 (the market less a 3% provider fee), that equates to roughly $10,656 as an upfront discount on the installation cost. Your installer typically handles the STC assignment and applies the discount directly to your invoice.

The deeming period decreases by one year annually, so systems installed in 2028 receive 3 years of deeming, 2029 receives 2, and so on. Delaying a year from now reduces the STC value by about 25%. See the full NSW incentive breakdown. Try the STC calculator to estimate your own certificate value.

VEECs: Victoria's additional state incentive

Victorian Energy Efficiency Certificates are a state-level incentive available exclusively in Victoria for commercial solar systems between 30 and 200 kW. VEECs are created under the Victorian Energy Upgrades program and represent ten years of deemed energy savings. Unlike STCs, VEECs do not diminish as 2030 approaches since the program operates on a fixed ten-year lifetime regardless of installation year.

The VEEC calculation uses one of two activity classifications. Activity 47A applies to systems up to 100 kW and uses an input factor of 0.133. Activity 47B covers systems from 100 to 200 kW with a higher input factor of 0.25, reflecting the greater energy displacement of larger systems. A regional factor of 1.04 applies to installations outside metropolitan Melbourne (against 0.98 inside it), providing a modest bonus for regional Victorian businesses.

Worked example: A 50 kW system in Melbourne (metro, Activity 47A) creates 50 × 0.133 × 10 × 0.98 = 65.2 VEECs. At a net certificate price of $72 (the market less a 10% provider fee), that delivers roughly $4,663 as an additional upfront discount on top of STCs. A regional installation in Geelong or Ballarat would generate 50 × 0.133 × 10 × 1.04 = 69.2 VEECs, or about $4,948.

Critically, VEECs stack with the federal certificates on Victorian installations between 30 and 200 kW. This means a 50 kW system in Melbourne receives both the STC discount and the VEEC discount, making Victoria the most incentive-rich state for mid-range commercial solar. See the full VIC incentive breakdown. Try the VEEC calculator to estimate your own certificate value.

LGCs: annual revenue for larger systems

Large-scale Generation Certificates apply to capacity above the STC ceiling (1 MW of site capacity from 1 October 2026, 100 kW before) and operate on a fundamentally different model. Instead of a one-time upfront discount, LGCs are earned annually based on actual metered generation. One LGC is created for every megawatt-hour (MWh) of electricity your system produces, and these certificates are sold on the open market to entities with obligations under the Large-scale Renewable Energy Target.

Worked example: 150 kW of capacity above the ceiling on a Brisbane (Queensland) site, producing approximately 211 MWh per year generates 211 LGCs annually. At the $7 per certificate this site currently quotes with (the market less a 5% provider fee), that is approximately $1,503 in revenue a year until the scheme closes in 2030. LGC spot spent years in the $40s and $50s and collapsed to single digits through 2026, so price a real project off the current forward curve rather than any older flat price; at today's prices an LGC stream rarely outweighs the upfront STC value on a comparable system.

LGC registration requires accreditation with the Clean Energy Regulator and metered generation data. Most businesses work with an LGC aggregator who handles the administration in exchange for a margin on the certificate price. See the full QLD incentive breakdown. Try the LGC calculator to estimate your own certificate revenue.

How incentives stack by state and system size

Not all incentives are mutually exclusive. The stacking rules depend on your state and system capacity:

• Victoria, 30–100 kW: STCs + VEECs. This is the highest-value combination for mid-range commercial systems. Both apply as upfront discounts and can be claimed simultaneously.
• Victoria, 100–200 kW: STCs on the whole system for installs from 1 October 2026, since it sits under the 1 MW ceiling; before then, STCs on the first 100 kW and LGCs on the balance. Either way, VEECs under Activity 47B apply on the full system capacity.
• All other states, up to 1 MW (100 kW before 1 October 2026): STCs only. No state-level scheme equivalent to VEECs currently exists in NSW, QLD, SA, or WA for commercial solar.
• Any state, above the STC ceiling: the system is split, with STCs on the capacity up to the ceiling and LGCs (annual) on the balance. For installs from 1 October 2026 the ceiling is a 1 MW site total at a fixed five-year deeming; before then it was 100 kW.

For installs before 1 October 2026, systems in the 80–120 kW range needed both scenarios modelled (staying under 100 kW versus going above it and earning LGCs on the balance). From 1 October 2026 the same question sits at the 1 MW site total, so model both sides of it on large sites. The crossover point depends on your electricity consumption profile, export volumes, and how long you intend to hold the system.

Model it yourself

Pick a state and adjust the system size below to see how STCs, VEECs, and LGCs apply to your installation. The calculator uses the same certificate prices Amperage quotes with and applies the correct zone multipliers and eligibility rules.

Next steps

The incentive landscape for commercial solar in Australia is generous but fragmented. Getting the numbers right requires matching your system size, location, and state-specific programs. Use the calculator above to run your own scenarios, or explore the detailed state-by-state breakdowns:

• Commercial solar payback calculator : see how these incentives change your payback period
• Solar incentives hub : national overview and calculator
• New South Wales
• Victoria
• Queensland
• South Australia
• Western Australia