STC value by zone and system size.

Certificates = kW x zone rating x deeming years, rounded down. 2026 installs get 5 years, 2027 installs get 4. Valued at $37 a certificate, a few dollars under the 2026 spot price to allow for trader fees. Zone 3 (rating 1.382): Bendigo, Ballarat, Shepparton, Mildura, plus parts of Melbourne's north and west such as Craigieburn, Epping, Melton and Sunbury. Zone 4 (rating 1.185): most of Melbourne, Geelong, Gippsland and Warrnambool. Zones from the Clean Energy Regulator's postcode table, checked 23 September 2026.

Certificates and value, 2026 installs (5-year deeming), $37 a certificate
System size	Zone 3 certificates	Zone 3 value	Zone 4 certificates	Zone 4 value
5 kW	34	$1,250	29	$1,050
6.6 kW	45	$1,650	39	$1,450
8 kW	55	$2,050	47	$1,750
10 kW	69	$2,550	59	$2,200
13.2 kW	91	$3,350	78	$2,900

The same systems installed in 2027 (4-year deeming)
System size	Zone 3 certificates	Zone 3 value	Zone 4 certificates	Zone 4 value
5 kW	27	$1,000	23	$850
6.6 kW	36	$1,350	31	$1,150
8 kW	44	$1,650	37	$1,350
10 kW	55	$2,050	47	$1,750
13.2 kW	72	$2,650	62	$2,300

Source: Clean Energy Regulator postcode zone ratings. Victorian postcodes are mapped today; Zones 1 and 2 and the other states follow as each range is checked.