LGCs are a measured product. One certificate represents one megawatt-hour of eligible renewable electricity above the baseline, so the number you create depends entirely on the quality of the meter data behind it. This is a major difference from STCs, which are deemed upfront from the system size and zone.
What the CER expects
Generation data must be captured as the electricity generated and consumed, in intervals of 30 minutes or less, measured by accredited electricity meters. With the National Electricity Market moving to five-minute settlement, it is sensible to specify meters that can record five-minute data as well. Meters generally need to hold records for at least 35 days, so retrieval has to be regular.
The CER also expects the arrangement to account for all energy flows, including auxiliary use at the station and losses between the generator and the meter. Before accreditation, you must show how your meters meet eligibility for LGC calculation. See the CER page on electricity meters for the current wording.
Building a clean metering arrangement
- Single-line diagram. Show every inverter, meter and the point of connection.
- Meter certification. Keep the test and calibration certificates.
- Net versus gross. Gross generation, net output and auxiliary load can be metered differently. Decide which approach you use and why: see net vs gross metering.
- Data source. Retailer or market data, an on-site data logger, or both.
- Consistency. Use the same data basis for each claim period.
Behind-the-meter sites
For behind-the-meter solar above 1 MW, you still need to measure total generation, not just exports. A site meter that only reads grid import and export will understate generation, and the CER will not accept a guess. See whether behind-the-meter solar is eligible.
What goes wrong
The usual problems are gaps in interval data, a meter replaced mid-year without a record, and mismatches between the meter and the claim period. Each can cause the CER to query or reduce a creation, and in an audit, missing calibration records are a common finding.
What this means for owners
Budget for metering from the design stage, not after construction. Talk to your metering provider about data formats the registry accepts, and set up a routine for retrieving and archiving data. Smaller commercial systems from 100 kW to 1 MW now take the deemed STC route from 1 October 2026 and avoid this burden. For the creation workflow, see creating LGCs and the REC Registry glossary. For small-scale needs, see resources and how it works.