The bookkeeping complexity in the renewable energy sector is not the solar panels — it is the certificate markets that sit alongside the physical installation. STCs and LGCs are tradeable instruments with their own recognition, measurement, and GST treatment that most standard bookkeeping workflows are not designed to handle.
Small-Scale Technology Certificates: Revenue Recognition for Installers
When a solar PV, solar hot water, or small wind system is installed by a Clean Energy Council-accredited installer, the installer is entitled to create Small-Scale Technology Certificates equal to the system's expected deeming period output. The number of STCs is determined by the system's capacity, location (solar zone), and the remaining deeming period under the Small-scale Renewable Energy Scheme.
The installer typically monetises these certificates immediately by assigning them to a registered agent — usually the system component supplier — in exchange for a discount on the equipment purchase price. This arrangement is called a "point-of-sale discount" and is the mechanism by which most residential customers see a reduced upfront installation cost.
From the installer's bookkeeping perspective, the STC assignment is a distinct revenue event. The gross installation revenue includes the value of the STC discount assigned; the cost of goods sold includes the full cost of equipment. Netting the STC value against equipment cost understates both revenue and COGS, misrepresenting the gross margin. GST applies to the STC assignment at the standard rate of 10% — the certificates are not financial instruments and the assignment is a taxable supply.
Large-Scale Generation Certificates: Inventory vs. Financial Instrument
Utility-scale solar, wind, and hydro generators receive one Large-Scale Generation Certificate per megawatt-hour of eligible renewable electricity generated and fed into the grid. The accounting treatment of LGCs depends on the generator's business model.
A generator that creates LGCs and sells them to electricity retailers under forward contracts is, in substance, holding inventory — the LGCs are produced goods that will be sold in the ordinary course of business. AASB 102 Inventories applies, and the LGCs are measured at the lower of cost and net realisable value.
A generator that creates LGCs and holds them speculatively — waiting for the spot price to rise — may be classifying them as financial instruments under AASB 9 Financial Instruments (specifically, as commodities held for trading). The measurement basis shifts to fair value through profit or loss. The choice of accounting policy has a direct effect on reported income volatility, so it requires deliberate policy selection and disclosure in the financial statements.
GST on LGC sales is at the standard rate of 10%. The LGCs are taxable supplies, not financial supplies — the GST financial supply provisions under Division 40 of the GST Regulations do not apply.
Feed-in Tariff Income: GST Registration Implications
The feed-in tariff is a per-kilowatt-hour credit paid by electricity retailers to small generators who export surplus electricity to the grid. For residential property owners, the FiT is generally not income from an enterprise — the household is not carrying on a business of electricity generation — and accordingly the household is not required to register for GST or declare the FiT as business income.
For commercial premises, the analysis differs. A business that installs solar on its commercial property and receives FiT payments is potentially carrying on an enterprise. If the FiT income, added to all other taxable and GST-free supplies of the enterprise, causes total annual turnover to exceed $75,000, GST registration is required under s.23-5 of the GST Act.
More practically, a business that is already GST-registered (as most commercial operators are) must treat FiT income as a taxable supply and remit GST on the payments received from the retailer. The electricity retailer's payment will typically not include GST — the retailer is not paying a GST-inclusive rate. The bookkeeper should confirm the contractual terms: if the FiT is stated as GST-inclusive, the GST component is 1/11th of the payment; if it is stated as GST-exclusive, the business owes GST on top.
Battery Storage Capital Allowances
Standalone battery storage systems installed at commercial premises are depreciating assets under Div. 40 ITAA 1997. Where the system is eligible, the instant asset write-off or temporary full expensing rules allow immediate deduction in the year of acquisition and installation. The effective life of a lithium-ion battery storage system under the Commissioner's determination is 10 years (ATO Tax Ruling TR 2024/1 or successor), though the taxpayer may self-assess a shorter period if the evidence supports it.
Battery systems that are integrated with a solar PV array — sharing the same inverter and forming a single system — are depreciated as a single asset of the same class as the solar system. The ATO's guidance on this point is that where components form an integrated system, they are treated as a single item for capital allowance purposes. Splitting an integrated system into components to maximise the write-off in the first year is not consistent with the law unless the components are genuinely separately depreciating assets.
Environmental Rehabilitation Provisions for Large-Scale Solar
Ground-mounted solar farms — utility-scale arrays typically developed on agricultural or pastoral land under long-term lease — almost invariably carry contractual rehabilitation obligations. The lease agreement (and sometimes the development approval conditions) will require the operator to remove all panels, racking, cabling, and transformers at the end of the lease term, and restore the land to approximately its pre-installation condition.
AASB 137 Provisions, Contingent Liabilities and Contingent Assets requires that a provision be recognised for this obligation as soon as the obligation arises — which is typically the date the first panel is installed, because from that point the disturbance has occurred and the obligation to remediate it is a present obligation of certain (though uncertain in amount) extent. The provision is measured at the best estimate of the expenditure required to settle the obligation, discounted to present value where the time value of money is material.
Discounting is invariably material for a 25–30 year asset. The unwinding of the discount (the accretion of the provision to its nominal value over time) is reported as a finance cost in the P&L, not as an operating cost. Bookkeepers working with large-scale solar clients should ensure the rehabilitation provision is calculated, reviewed annually, and correctly presented in the financial statements — its omission is a material misstatement and a common audit finding in the sector.