May 13, 2026

STC Claim Process: Step-by-Step Guide for Australian Solar Installers (2026)

Small-scale Technology Certificates (STCs) are the financial backbone of Australia’s residential solar market. For most homeowners, the STC discount makes the difference between solar being affordable or out of reach. For solar installation businesses, STCs represent a significant revenue stream — and a compliance minefield if you get the process wrong.

The Clean Energy Regulator runs one of Australia’s most active small business audit programs. In 2025 and into 2026, STC compliance has been a primary enforcement focus — with audits triggered by documentation errors, system size discrepancies, and installer scope violations that businesses didn’t even know they’d committed.

This guide walks through the complete STC process: eligibility, calculation, customer declarations, lodgement, and the errors that most commonly trigger CER attention.

What Are STCs and How Do They Work?

Under the Small-scale Renewable Energy Scheme (SRES), eligible solar PV, solar hot water, and small-scale wind systems create Small-scale Technology Certificates. Each certificate represents 1 megawatt hour of renewable energy the system is expected to generate (or displace) over its deeming period.

For residential solar PV in 2026:

Systems up to 100kW are eligible under the small-scale scheme
STCs are calculated based on system size, location (installation zone), and deeming period
The deeming period is the number of years from installation to 2030 (the current end of the SRES scheme)
STCs are sold on the market — either direct to buyers or through STC traders at the point of sale

Point-of-sale discount: Most residential solar installations use the STC value as an upfront discount at the point of sale. The customer assigns the right to create STCs to the installer (or the trader), who then lodges and sells the certificates. The customer gets a lower system price; the installer recovers the discount value plus a small handling margin from the STC market.

STC Calculation

The number of STCs a system creates is calculated as:

STCs = system size (kW) × zone rating × deeming period (years)

Installation zones: Australia is divided into four zones based on solar irradiance:

Zone 1 (highest irradiance): Darwin, north QLD — zone rating 1.536
Zone 2: Brisbane, Perth, north SA, much of WA — zone rating 1.382
Zone 3: Sydney, Adelaide, south QLD, most of VIC — zone rating 1.185
Zone 4 (lowest irradiance): Melbourne, Hobart, ACT — zone rating 1.044

Deeming period: As of 2026, the deeming period is the number of years remaining until 31 December 2030. If installation is in 2026, the deeming period is approximately 4 years (to end of 2030). From 2027, it will drop to 3 years — meaning STCs, and therefore STC discounts for customers, will reduce significantly.

Example calculation (2026 install, Zone 3, 6.6kW system): 6.6 × 1.185 × 4 = 31.28 STCs (rounded down to 31 STCs)

At a market price of $36/STC: $1,116 STC value

Important: Always use the CER’s STC calculator (available on their website) rather than manual calculation for lodgement. Manual calculation errors are a primary audit trigger.

Installer Eligibility Requirements

You can only create STCs for systems you install if you meet the eligibility requirements.

CEC Accreditation

You must be accredited by the Clean Energy Council (CEC) to design and install eligible solar PV systems. Your accreditation endorsement must match the work you perform:

Grid-connect PV systems: Required for all grid-tied solar installations
Battery storage systems: Separate endorsement required for battery installations
Off-grid systems: Separate endorsement required

Installing work outside your endorsed category is a serious compliance violation that invalidates the STCs and may result in accreditation suspension.

Check your accreditation certificate before every new job type. If you’re adding batteries to your offerings and don’t have the battery endorsement, get it before you install, not after.

Equipment Eligibility

Only equipment on the CEC approved products list can be used in STC-eligible installations. Check the CEC list before purchasing new panel or inverter brands — not all products sold in Australia are on the approved list.

The Customer Declaration

The customer must sign a declaration confirming that the system was installed as described and that they assign the right to create STCs to the installer or trader. This is a legal document and a mandatory component of every STC claim.

What the declaration covers

The customer is declaring:

The system was installed at the address specified
The system specifications match what’s stated (size, equipment brands, model numbers)
They have not previously claimed STCs for this system
They assign the right to create STCs as specified

Common declaration errors

Missing signatures: The declaration must be signed by the legal owner of the premises (or their authorised representative). A tenant cannot sign for a system on a property they don’t own.

Date discrepancies: The declaration date should match the installation date on your records. Date discrepancies trigger CER queries.

Specification mismatches: If the declaration says 6.6kW but your installation records show 6.5kW (due to a module substitution on the day), there’s a discrepancy. Fix it before lodgement, not after.

Store declarations digitally. Every signed customer declaration should be scanned and stored against the job record in your job management system. If you’re using ServiceM8, attach the signed PDF to the job — you’ll need it if the CER requests it in an audit, sometimes months or years later.

Step-by-Step: How to Lodge STCs

Option 1: Lodge directly through the CER’s REC Registry

For businesses that want to sell STCs on the open market or hold them for a better price:

Register as a registered person in the REC Registry (one-time process)
For each installation, create an STC claim in the Registry:
- Enter installation address
- Enter system specifications (panel brand/model, inverter brand/model, system size)
- Enter installation date
- Enter installer accreditation number
- Confirm customer declaration obtained
Once created, STCs can be sold through the Registry to registered agents, large energy retailers, or the clearing house
The clearing house buys at a fixed price of $40/STC — a guaranteed floor price, but lower than open market during periods of high demand

Timeline: STCs must be lodged within 12 months of installation. Don’t let this deadline slip.

Option 2: Assign to an STC trader (point-of-sale discount)

Most residential solar businesses use registered STC traders who manage the lodgement process in exchange for a small handling fee. The typical arrangement:

The trader manages the REC Registry lodgement
The trader pays the installer the STC value minus their margin ($1–$3 per STC typically)
The customer gets the STC value as a point-of-sale discount on the system price

Key requirements when using a trader:

The customer’s assignment of rights must be made to the trader (not the installer) — your paperwork must reflect this
The trader must be registered with the CER — verify their registration before engaging them
Keep records of the assignment and the trader arrangement — you’re still responsible if the trader makes an error

Common STC Errors That Trigger CER Audits

The CER’s audit selection criteria include patterns and anomalies — businesses that consistently show certain error types end up in audit streams. Here’s what to avoid:

1. System size discrepancy Your REC Registry lodgement says 6.6kW but your CEC accreditation records, job paperwork, and network connection form collectively suggest a different system size. Even minor discrepancies (different module counts, rounded vs. actual sizing) trigger queries.

Fix: Ensure all documentation — quote, customer declaration, connection application, Registry lodgement — uses the exact same system specification numbers.

2. Installer scope violations Lodging STCs for battery storage installations without the battery storage endorsement is one of the CER’s most common enforcement actions in 2026. It’s often not intentional — the installer had the solar endorsement and added batteries without realising a separate endorsement was required.

Fix: Before adding any new system type to your offerings, check your endorsement certificate. Get the endorsement first.

3. Equipment not on approved list Using panels or inverters not on the CEC approved products list — often a result of supplier substitution (“same specs, different brand”) — invalidates the STC claim entirely.

Fix: Check the CEC list every time you’re considering a product substitution. Don’t rely on supplier assurances.

4. Missing or late customer declarations Lodging STCs without a signed customer declaration, or with a declaration dated after the lodgement date, is a documentation failure that creates audit risk.

Fix: Make customer declaration signing a mandatory step in your installation workflow — before the panel goes on the roof, not on the way out the door.

5. Lodgement outside 12 months Late lodgement of STCs — beyond 12 months from installation date — means the certificates are invalid. In a busy business without systematic tracking, jobs can slip past this deadline.

Fix: Track STC lodgement deadlines in your job management system. ServiceM8 allows you to add follow-up tasks against jobs with due dates — use this to flag STC lodgement deadlines 30 days before they expire.

Managing STCs at Scale

For a business doing 15+ installations per month, STC management is a significant administrative function. Without a system, it’s a major compliance risk.

The minimum viable system:

Job record per installation — with full system specs, installation date, customer contact, and declaration storage
STC lodgement tracked against each job — lodgement date, Registry reference number, STC count, value received
Monthly reconciliation — compare jobs completed vs. STCs lodged, identify gaps
Deadline alerts — flag jobs approaching the 12-month lodgement deadline

Build this into your job management workflow, not a separate spreadsheet. Spreadsheets get out of sync; a job management system with the right workflow built in stays current automatically.

For the complete CER audit preparation framework — including what auditors look for and how to pass — see our CER Audit Prep guide for solar installers.