Methodology: where every number on this site comes from

Prices: the Solar Scorecard Price Index

The index reads the Solar Choice Price Index residential tables (standard and premium installer offers, 3 to 10 kW, eight capitals) on or after the first of each month. Offers are what installers submit to a quote platform, not what homeowners paid; Solar Choice does not publish how many offers sit behind each cell, so no page on this site states a sample size for those figures. We interpolate 6.6 kW between 6 and 7 kW and 8 kW between 7 and 10 kW, and scale 13 and 20 kW from 10 kW using the ratio in Solar Choice's commercial index. Cities Solar Choice does not index show the nearest indexed capital and say so on the page. The October 2026 baseline is $6,774 standard and $8,084 premium for 6.6 kW nationally. The series is published at /data/pricing-history.json and explained on the price history page.

Quotes series. The quotes series started on 28 October 2026. Every quote submitted through the quote check is stored (postcode, nearest indexed city, size, brands, tier, price after STCs, storeys, the STC line if given, and the month; nothing personal) and pooled by city and size. Once a cell holds ten or more quotes we publish its median and quartiles with N and the window, and the city page says which figure it is showing. Until then each page says it is showing offers. The first cells can become eligible in the November 2026 reading if ten checks arrive for one city and size before 24 November 2026; the count per cell is reported on the price history page from that reading.

The quote reader. Since 28 October 2026 the quote check also accepts a photo or PDF of a quote. The file is sent once to an AI model (Anthropic's Claude through its API) that returns the printed figures as structured data; the model is instructed to return no names, addresses, phone numbers or email addresses, and the function removes anything that looks like one. The figures are then marked by the same rules as the typed check, plus the inverter and battery against the public list prices on this site and each add-on against its sourced range; every rule and every reference figure is in the public quote-reader.json. The file is not stored. If the verdict leads you to ask for competing quotes, the figures shown in the result (postcode, city, size, price after STCs, the panel, inverter and any battery named, and the roof read if you added an address) are sent with your name, mobile and email to up to two installers, who may contact you; the file is still not sent or stored, and asking for quotes does not add the quote to the quotes index. The reader shows every line it read and how it classified it, so a misread is visible; it is a first read, not a ruling, and the typed form stands behind it. The roof reader. From 28 October 2026 an address can be read into a roof: the Google Geocoding API gives the point, the Google Solar API gives the building's roof segments (pitch, compass direction, area, annual sunshine with shade) and the energy of each panel position. We convert Google's 250 W reference panel to 440 W panels by area, derate DC to AC at 0.85 (Google's default), take the per-kW yield of the best positions for each size on the ladder, and price each size that fits from the index for the nearest indexed city. "Your number" is the largest size under 10 kW that fits. In a quote check the roof yield replaces the city average for output and payback, and the quoted size is checked against what the roof takes. The address is not stored; the method is on the roof page. The bill reader. From 29 October 2026 the scorecard also accepts a photo or PDF of a power bill. The file is sent once to the same AI model, which returns the printed figures as structured data: retailer, state, postcode, billing period, tariff type, supply charge, usage rates and kilowatt-hours by band, controlled load, solar export and feed-in, the total and whether GST is included. The model is instructed to return no name, address beyond the postcode, NMI, meter number, account number, phone number or email address, and the function keeps only the figure fields, so anything of that kind is dropped before the result is logged or sent. The figures are annualised (period kilowatt-hours times 365 over the days billed, flagged when the period is under 25 days), blended into one usage rate weighted by the kilowatt-hours in each band, and compared with the state reference in the public bill-reader.json: the default-offer usage rate from pricing.json and the median residential daily supply charge across the CDR plan dataset. On a time-of-use bill the share of general usage in the peak and shoulder windows is reported as the evening share. The scorecard and the quote check then price savings and payback at the bill's usage and feed-in rates instead of the state default, and say so. The file is not stored; reads are limited to ten an hour per connection.

The example scorecard on the home page shows the index figures for the city or suburb named on the card: the same 6.6 kW standard offer, yearly saving and payback that are printed on that page, read from the built page and never recomputed.

The STC discount

Certificates = kW x zone rating x deeming years, rounded down, as the Clean Energy Regulator calculates them. Zone ratings 1.622, 1.536, 1.382 and 1.185 for Zones 1 to 4; 5-year deeming for 2026 installs, one year less each January to 2030. Price: $39 per certificate. Spot traded at $39.9 in the week of 19 to 23 October 2026 (Ecovantage) and a price board showed $39.65 on 27 October (Demand Manager); the clearing house is capped at $40. Installers assign the certificates and carry a trading cost for which no published figure exists, so we round down to $39. This is one field in pricing.json; changing it moves every STC figure on the site.

The federal battery discount

Cheaper Home Batteries Program: 6.8 certificates per usable kWh for installs from 1 May to 31 December 2026, 100 per cent of capacity to 14 kWh, 60 per cent from 14 to 28 kWh, 15 per cent from 28 to 50 kWh, rounded down, valued at the STC price above. The factor falls to 5.7 on 1 January 2027 and half-yearly after that; the schedule is in pricing.json.

State schemes

Each state and territory scheme was read on the government's own page on 27 October 2026, with the status, amount, eligibility and URL recorded in rebates.json. Where a page did not state a fact, the field is null and the site says so. The Victorian $1,400 solar panel rebate is recorded as open, in monthly allocations to 30 June 2027, on the wording of solar.vic.gov.au as updated 21 October 2026; several comparison sites say it closed in March 2026. Schemes are re-read monthly.

Tariffs and feed-in

Usage rates are state default-offer figures for 2026-27 (AER Default Market Offer, Victorian Default Offer, regulated tariffs in WA, TAS, ACT and NT) carried in pricing.json; feed-in tariffs are retailer offer medians via WhySolar as at 15 October 2026 and Aurora's regulated minimum in Tasmania. Savings use 35 per cent self-consumption: saving = kWh x (0.35 x usage rate + 0.65 x feed-in). Payback = price after STC / saving.

Output and lifetime cost

Monthly output uses Bureau of Meteorology mean daily global solar exposure for the nearest station (shown with its station number on every page) and an annual yield in kWh per kW. For the capitals the yield is the Clean Energy Council consumer guide table (December 2012 edition, the last to carry it; no newer edition publishes one); for the other twelve cities it is derived from BoM exposure using the implied ratio of the nearest capital and labelled as derived. Lifetime cost per kWh = price after STC / 25 years of output at 0.5 per cent a year degradation (Qcells warranty wording; Jinko and Trina warrant 0.4 per cent). We treat 0.5 as conservative.

Postcode installation data

Installation counts and capacity by postcode are the Clean Energy Regulator's small-scale installation postcode data, 30 September 2026, downloaded 2026-10-27 (CC BY 4.0; based on Clean Energy Regulator material licensed under a Creative Commons Attribution 4.0 licence). The 12-month window is October 2025 and September 2026; the CER notes that recent months rise for up to twelve months as certificates are created, so the latest months are undercounts. "Registered systems per 100 private dwellings" divides the all-time CER count by the ABS 2021 Census private dwelling count for the postal area (table G36); it counts replacements and upgrades and is our own metric, not the Australian PV Institute's percentage of houses with solar, which we do not republish because the APVI map carries a citation line and no licence (status recorded in apvi-postcodes.json).

Network rules

Each suburb is mapped to its electricity distributor from published postcode lists (the AER's Energy Made Easy supply-area data, the CitiPower and Powercor network locator, Western Australian and Northern Territory government sources), 295 of 317 suburbs resolved; split Victorian suburbs with no published sub-suburb boundary are left unmapped. Inverter and export limits come from each distributor's own connection standard, recorded with URLs and the date checked in distributors.json. Energex, Ergon Energy and Power and Water block automated reading of their pages, so their limits are blank until read by hand. Coastal flags use the Geoscience Australia coastline and estuary mapping with a 1,000 m threshold.

Component costs and the floor

The "too cheap" floor adds the lowest trade prices we could fetch on 27 October 2026 for compliant panels, a 5 kW inverter, tin-roof racking, two people for a day at Electrical Award minimum rates, and the certificate and connection fees, plus GST, less the STCs. Every component and its source is in pricing-additions.json. The floor excludes cable, isolators, overheads, warranty provision and margin, so a fair price sits well above it.

What we do not know

• How many offers sit behind each Solar Choice figure.
• What installers actually pass through for STCs; we assume $39 against a $39.90 spot.
• Export limits for Energex, Ergon Energy and Power and Water, and single-phase export limits for Ausgrid, until their pages are read by hand.
• Meter exchange fees by retailer and state; none is published nationally.
• Travel surcharges outside metro areas and long cable run pricing; no sourced figure exists.
• Which network serves 22 split Victorian suburbs below suburb level.
• A current Clean Energy Council yield table; the 2012 edition is the last published.

Update cadence and change log

Prices, STC price, battery factor and state schemes are re-checked monthly; the next review is 24 November 2026. The CER postcode data is refreshed when the CER publishes (monthly). Distributor rules are re-read quarterly or when a distributor announces a change. Every data change is one line in changelog.json with the old value, the new value and the source.

Methodology questions

Sources and data files

Prices checked 27 October 2026. Next review 24 November 2026. STC price assumption: $39 per STC.

1. Solar Choice Price Index
2. Clean Energy Regulator postcode data
3. ABS 2021 Census DataPacks (G36)
4. Ecovantage STC market update
5. Demand Manager price board
6. CER clearing house price
7. Solar Victoria solar panel rebate
8. Bureau of Meteorology climate statistics
9. APVI Solar Map (citation line, no licence)
10. pricing.json
11. rebates.json
12. distributors.json
13. irradiance.json
14. cer-postcodes.json
15. pricing-additions.json
16. changelog.json