The number of LGCs is a metering question: one LGC for each megawatt hour of eligible generation. The value is that number multiplied by a market price that has been low in 2026.
The generation estimate
A rooftop system in most Australian capitals produces roughly 1,300 to 1,600 kWh for each kW installed per year, depending on location, tilt, shading and inverter loading. For 100 kW that is about 130 to 160 MWh, so roughly 130 to 160 LGCs a year.
What that is worth
At the verified spot range of about $6 to $9 in September 2026 (after a low near $4 in February):
| Certificates a year | At $6 | At $9 |
|---|---|---|
| 130 | about $780 | about $1,170 |
| 160 | about $960 | about $1,440 |
That is a low single-digit percentage of the electricity bill a 100 kW system offsets, and LGC prices could move either way. See the LGC spot price answer for the range.
The catch for a system this size
LGCs are for larger systems that register as power stations. The Small-scale Renewable Energy Scheme covers solar up to 100 kW, creating STCs for the installer’s customer at the point of sale. A system of 100 kW or under that meets the scheme conditions is therefore normally a small-scale system. Above 100 kW, the question is whether you take STCs or LGCs.
From 1 October 2026, systems above 100 kW and up to 1 MW can create STCs, using a fixed five-year deeming period. CER says applications for these open from mid to late November 2026. Above 1 MW remains LGCs. Our mid-scale solar STCs pillar covers the rules, and the LGC or STC answer deals with the boundary.
STC comparison for a system just over 100 kW
An illustration for a 150 kW system in a zone 3 city such as Sydney (rating 1.382): 150 x 1.382 x 5 = 1,036 STCs at upfront. At roughly $38 to $40 each that is about $39,000 to $41,000 on day one, against under $2,500 a year in LGCs for the same panels. Over five years LGCs total less than a fifth of the STC value. Use the STC calculator for the real number.
Generation is not constant
Output varies year to year with weather, degradation of about half a percent a year and any curtailment by the network. Use a conservative figure for the first year and expect a slow decline in certificates, not a flat line.
What this means for you
If you are scoping a commercial job around 100 kW, the certificate decision is no longer a reason to shave the array to fit under the cap. Read the LGC pillar, then pricing for current STC settlement rates and STC trading for how a claim runs.