STC vs VEEC vs LGC: Which Fits Your Business?

In short: STCs are the federal upfront discount on systems up to 100 kW (about $13,475 on a 50 kW Sydney system installed in 2026). VEECs are a Victoria-only upfront bonus for 30–200 kW systems (about $5,370 on a 50 kW metro Melbourne install) that stacks on top of the federal certificates. LGCs replace the upfront model above 100 kW with annual revenue per megawatt-hour generated (about $1,634 a year on a 150 kW Brisbane system at the $8 default price this site quotes with – LGC prices move, so treat it as a snapshot). Victoria between 30 and 100 kW is the richest combination; everywhere else it is STCs up to 100 kW and LGCs beyond.

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 systems up to 100 kW. VEECs add a Victoria-only bonus for systems between 30 and 200 kW. LGCs generate ongoing annual revenue for systems above 100 kW.

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 systems up to 100 kW. 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 2026, that means 5 years of deemed generation credited upfront at the point of installation.

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 2026 generates 50 × 1.382 × 5 = 346 STCs. At a certificate price of $39, that equates to roughly $13,475 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 2027 receive 4 years of deeming, 2028 receives 3, and so on. Delaying a year from now reduces the STC value by about 20%. 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 certificate price of $82, that delivers roughly $5,370 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 $5,699.

Critically, VEECs stack with STCs for Victorian installations between 30 and 100 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 systems above 100 kW 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: A 150 kW system in Brisbane (Queensland) producing approximately 211 MWh per year generates 211 LGCs annually. At the $8 per certificate this site currently quotes with, that is approximately $1,634 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: LGCs on the metered output (the whole system registers as a power station once it passes 100 kW) + VEECs under Activity 47B on the full system capacity. There is no partial STC claim on the first 100 kW.
• All other states, up to 100 kW: STCs only. No state-level scheme equivalent to VEECs currently exists in NSW, QLD, SA, or WA for commercial solar.
• Any state, above 100 kW: LGCs on the full system output (annual) instead of STCs. The two federal schemes never split one system: it is either deemed upfront (STCs) or metered annually (LGCs). The registered SRES expansion moves systems installed from 1 October 2026 onto whole-system STCs at a fixed five-year deeming, up to a site total of 1 MW; above that total, LGCs still apply.

For systems in the 80–120 kW range, modelling both scenarios (staying under 100 kW for maximum STC value versus going above 100 kW to access LGC revenue) is essential. 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