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Guide, checked 5 November 2026

How many STCs does a solar system get?

Panel STCs come from the size, the zone and the install year. Battery STCs come from the usable kWh and the install date. Here is the sum, and the number for the common sizes.

The formula

For rooftop and ground-mounted solar up to 100 kW, one STC is one megawatt hour of electricity the system is deemed to generate between the install and the end of the scheme in 2030:

STCs = kW x zone rating x deeming years, rounded down.

  • kW is the rated panel capacity, not the inverter.
  • Zone rating is 1.185 to 1.622 megawatt hours a year per kW, set by the install postcode.
  • Deeming years is 5 for a 2026 install, 4 for 2027, and falls by one every 1 January.

Worked example: 6.6 kW in zone 4, installed in 2026. 6.6 x 1.185 x 5 = 39.105, so the job gets 39 STCs. The part after the decimal point is dropped, never rounded up.

STCs per kW by zone and year

The rating times the deeming years is the number of STCs each kW earns, before rounding. Multiply by the size of the system:

Installed inYearsZone 1Zone 2Zone 3Zone 4
Rating1.6221.5361.3821.185
202658.11 per kW7.68 per kW6.91 per kW5.925 per kW
202746.488 per kW6.144 per kW5.528 per kW4.74 per kW
202834.866 per kW4.608 per kW4.146 per kW3.555 per kW
202923.244 per kW3.072 per kW2.764 per kW2.37 per kW
203011.622 per kW1.536 per kW1.382 per kW1.185 per kW

Zone 1: inland areas and the north-west. Zone 2: Darwin and parts of the inland and west. Zone 3: Sydney, Brisbane, Perth, Adelaide, Canberra. Zone 4: central Melbourne, Hobart. Every postcode and its zone.

STCs by system size

Whole certificates, rounded down, for systems installed in 2026:

SystemZone 1Zone 2Zone 3Zone 4
3 kW24232017
5 kW40383429
6.6 kW53504539
8 kW64615547
10 kW81766959
13.2 kW1071019178
15 kW12111510388
20 kW162153138118
30 kW243230207177
50 kW405384345296
66 kW535506456391
100 kW811768691592

The same sizes for systems installed in 2027, with 4 deeming years:

SystemZone 1Zone 2Zone 3Zone 4
3 kW19181614
5 kW32302723
6.6 kW42403631
8 kW51494437
10 kW64615547
13.2 kW85817262
15 kW97928271
20 kW12912211094
30 kW194184165142
50 kW324307276237
66 kW428405364312
100 kW648614552474

Systems over 100 kW follow different rules, below. Sizes in between, or a zone and year not shown, are in the calculator.

What the common sizes are worth

Three common sizes, at $38.64 per STC, what we pay on a home system as at 5 November 2026:

Installed in 2026

SystemZone 1Zone 2Zone 3Zone 4
6.6 kW53 STCs, $2,047.9250 STCs, $1,93245 STCs, $1,738.8039 STCs, $1,506.96
10 kW81 STCs, $3,129.8476 STCs, $2,936.6469 STCs, $2,666.1659 STCs, $2,279.76
13.2 kW107 STCs, $4,134.48101 STCs, $3,902.6491 STCs, $3,516.2478 STCs, $3,013.92

Installed in 2027

SystemZone 1Zone 2Zone 3Zone 4
6.6 kW42 STCs, $1,622.8840 STCs, $1,545.6036 STCs, $1,391.0431 STCs, $1,197.84
10 kW64 STCs, $2,472.9661 STCs, $2,357.0455 STCs, $2,125.2047 STCs, $1,816.08
13.2 kW85 STCs, $3,284.4081 STCs, $3,129.8472 STCs, $2,782.0862 STCs, $2,395.68

The price per STC moves with the market, so check the date beside any price. What to check in any trader.

Why zone and install year matter

Two systems of the same size can earn different numbers. The zone follows the install postcode, so a 6.6 kW system gets 39 STCs in Melbourne and 45 in Sydney. STC zones and ratings has every postcode range.

The install year sets the deeming years, and the installation date decides it, not the sale date or the date the certificates are created. A 6.6 kW system in zone 4 drops from 39 STCs to 31 when it moves from a 2026 install to a 2027 install. The deeming period to 2030 shows each year.

Batteries: STCs per kWh

A battery earns STCs on its usable capacity in kWh, times a factor that depends on the install date and steps down every six months to the end of 2030. The factor is 6.8 for May to Dec 2026, and 5.7 from 1 January 2027. Capacity is tapered: the first 14 kWh counts in full, 14 to 28 kWh counts at 60%, 28 to 50 kWh counts at 15%. Only the first 50 kWh counts. The zone does not matter, and the kW rating does not count.

Usable kWhMay to Dec 2026 (6.8)Jan to Jun 2027 (5.7)Jul to Dec 2027 (5.2)
5 kWh34 STCs, $1,313.7628 STCs, $1,081.9226 STCs, $1,004.64
10 kWh68 STCs, $2,627.5257 STCs, $2,202.4852 STCs, $2,009.28
13.5 kWh91 STCs, $3,516.2476 STCs, $2,936.6470 STCs, $2,704.80
20 kWh119 STCs, $4,598.16100 STCs, $3,86491 STCs, $3,516.24
30 kWh154 STCs, $5,950.56129 STCs, $4,984.56118 STCs, $4,559.52
50 kWh174 STCs, $6,723.36146 STCs, $5,641.44133 STCs, $5,139.12

Dollar figures at $38.64 per STC as at 5 November 2026. Battery STCs has the full table to 2030 and the paperwork.

Over 100 kW

Solar over 100 kW and up to 1 MW installed from 1 October 2026 can also create STCs, with a fixed five-year deeming period that does not fall each January. The regulator has not published a formula for it, only a calculator, so the tables above stop at 100 kW. Mid-scale solar STCs has the rules and our estimate.

Heat pumps and solar water heaters

These do not go by size. The regulator's register gives each model a number of STCs for each hot water zone, and the claim is that figure times a factor for the install year. STCs for heat pumps and solar hot water explains how to read it.

For an exact job

Put the install postcode, the system size and the install date into the STC calculator. It uses the same zones, deeming years and battery factors as this page, shows the zone, and works out panels and battery together, for any install date to 2030.

FAQ

Common questions

How many STCs for a 6.6 kW system?

For a 2026 install, 39 STCs in zone 4 (Melbourne, Hobart), 45 in zone 3 (Sydney, Brisbane, Perth, Adelaide, Canberra), 50 in zone 2 and 53 in zone 1. At $38.64 per STC, what we pay on a home system, that is $1,506.96 in zone 4 and $1,738.80 in zone 3. For a 2027 install it falls to 31 in zone 4 and 36 in zone 3.

How many STCs per kW of solar panels?

It depends on the zone and the install year. For a 2026 install it is 5.925 STCs per kW in zone 4 and 6.91 in zone 3, up to 8.11 in zone 1, before rounding down to a whole certificate. That is the zone rating times the 5 deeming years left.

How many STCs per kWh for a battery?

6.8 STCs per usable kWh for May to Dec 2026, on the first 14 kWh. The factor falls to 5.7 on 1 January 2027. Capacity above 14 kWh is tapered: the first 14 kWh counts in full, 14 to 28 kWh counts at 60%, 28 to 50 kWh counts at 15%. A 13.5 kWh battery gets 91 STCs, and a 50 kWh battery 174.

How many STCs per kW for a battery?

A battery is not paid by its power rating in kW. STCs follow the usable capacity in kWh, times the factor for the install date, so a battery with a high kW rating and a small capacity earns no more than any other battery of that capacity. Use the usable kWh on the Clean Energy Council's approved battery list, not the nominal figure and not the kW.

Why does the same system get a different number of STCs on another quote?

Usually the zone, the install year or the rounding. The zone follows the install postcode, the deeming years fall every 1 January, and the total is rounded down to a whole certificate. A quote that assumes last year's deeming years will show more STCs than the job can claim, and the wrong zone can show more or fewer.

How are STCs calculated?

For panels, the system size in kW times the zone rating times the deeming years left, rounded down. For a battery, the usable kWh (tapered above 14 kWh) times the factor for the install date, rounded down. Solar water heaters and heat pumps are read from the regulator's register by model and zone, and mid-scale solar over 100 kW has its own fixed deeming period.

Related guides

Claims paid in 1 business day

$38.64 + GST per STC, with nothing taken off. You get the price shown on the day you submit a complete claim, and there is no lock-in or minimum.

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