For about a decade, the 100 kW line was one of the most important numbers in commercial solar design. At 99 kW you took STCs upfront. At 101 kW you became a power station, and the value arrived as LGCs, a few cents at a time, for the life of the scheme. Designers sized systems to either side of that line on purpose.
From 1 October 2026 the line has moved. The Small-scale Renewable Energy Scheme now covers solar PV above 100 kW and up to 1 MW installed from that date, with a fixed five-year deeming period. That changes the decision from “stay under 100 kW or not” to “is there any reason to go to LGCs at all”. The short answer for most sites is no, and this page shows the numbers behind it.
The two certificates, side by side
| STC (small-scale) | LGC (large-scale) | |
|---|---|---|
| Created | Upfront at installation | After generation, as the system produces |
| Basis | kW x zone rating x deeming years | 1 per MWh generated above any baseline |
| Size | Up to 100 kW; from 1 Oct 2026, up to 1 MW | Power stations, including systems above 1 MW |
| Price at the time of writing | About $38 to $40 | About $6 to $9 (roughly $8 in late September 2026) |
| Paperwork | Installer accreditation, product eligibility, claim | Power station accreditation, metering, generation returns |
| Ends | Scheme ends 31 December 2030 | RET ends 2030 |
The mid-scale pillar page is mid-scale solar STCs. For the basic difference, see LGC vs STC.
Worked example 1: the old 99 kW design
A 99 kW system in zone 3 in 2026 creates 99 x 1.382 x 5 = 684 STCs, about $26,000 at $38. That was the prize for staying under the line.
Worked example 2: the new 250 kW design
A 250 kW system in zone 3, installed from 1 October 2026, creates 250 x 1.382 x 5 = 1,727 STCs. At $38 that is $65,626, and at $40 it is $69,080. In zone 4 (Melbourne), 250 x 1.185 x 5 = 1,481 STCs, about $56,300. The CER says applications open mid to late November 2026, so certificates for systems installed in October will wait until then to be created.
At the old 100 kW limit, the owner of a 250 kW roof would have built 99 kW and left 150 kW of roof unused, or taken LGCs on the full system.
Worked example 3: what the LGC path pays
A 250 kW system in a sunny zone 3 location might generate roughly 375 MWh a year (about 1,500 kWh per kW). That is 375 LGCs a year. At $8 each, that is $3,000 a year. Over the four years to the end of 2030, about $12,000 at today’s price, less the cost of accreditation, metering and the agent’s cut.
| Path | Value, 250 kW zone 3 | When it arrives |
|---|---|---|
| STCs at $38 | about $65,600 | Upfront, once certificates are created |
| LGCs at $8 | about $3,000 a year, about $12,000 to 2030 | Spread over the years |
The break-even
The break-even LGC price is the one at which the LGC path pays what the STC path does. Using the 1,727 STCs ($65,626) and about 1,500 LGCs created from late 2026 to the end of 2030 (375 a year for four years), the break-even is about $44 per LGC. The spot price has been $6 to $9 in 2026, after a low near $4 in February and around $11 at the start of Q4 2025. The regulator and market commentators have described the market as oversupplied to 2030. A fivefold rise would be needed. That is why STCs win for any system that qualifies. You can run your own numbers in the STC calculator.
Where LGCs and larger systems still fit
- Above 1 MW. Systems of more than 1 MW remain power stations that create LGCs. At around $8 a certificate, a 1.5 MW system generating 2,250 MWh would earn about $18,000 a year in LGCs, so it is not the main driver of project returns. See how to sell LGCs.
- Existing power stations. Systems accredited before the change keep creating LGCs. Whether an existing mid-scale power station could switch is a question for the CER.
- Sites with unusual yield. Very high-yield systems create more LGCs per kW, but the break-even stays far from the market.
- Eligibility problems. A system that cannot meet the installer or product requirements for STCs, such as products outside the Clean Energy Council list, may only have the power station route. The 1 MW expansion requires SAA-accredited design and installation and approved products.
Practical checks before choosing
- Installation date. Systems installed before 1 October 2026 are outside the expansion.
- Capacity measure. Confirm how the CER measures capacity for the 1 MW limit.
- Accreditation. Confirm your designers and installers hold the right SAA accreditation.
- Approvals. Network connection and planning approvals must be in place before the installation date counts.
- Output limits. The old 250 MWh annual output limit applied to systems up to 100 kW. Check the CER’s current guidance on whether any output test applies above 100 kW.
For installers
Cash flow changes at the commercial end. A $65,000 certificate claim is larger than a month of residential income for many crews, so check how your trader handles claims of that size and their pre-check process. Review the cash flow guide and the trading guide. See also the 100 kW limit answer.
A quick decision table by site type
| Site | Likely best path | Why |
|---|---|---|
| Warehouse, 150 to 400 kW, installed from 1 Oct 2026 | STCs, mid-scale | Upfront discount of about $39,000 to $105,000 at $38 in zone 3, depending on size |
| Farm with a 600 kW array and strong daytime load | STCs, mid-scale | Same logic, and the discount scales with kW |
| Small business, 30 to 99 kW | STCs, small-scale | No change, but check the 2027 deeming drop to four years |
| Developer building 2 MW | LGCs | Above the 1 MW limit |
| Existing 300 kW power station, accredited before 1 Oct 2026 | LGCs | Already in the large-scale scheme; ask the CER about options |
| Site with network export limits | Size to the limit, then STCs | The connection decides the system size more than the certificate |
If you sit between two rows, the break-even of about $44 per LGC is a useful sanity check. At $8, the STC route is the better choice by a wide margin for any system that qualifies. See commercial solar over 100 kW and LGCs for the earlier rules.
What to do next
- Re-price any commercial quote that was designed around 99 kW.
- Check installation dates against 1 October 2026.
- Read the explainer on the 100 kW to 1 MW expansion and the pillar page for LGCs.
- When mid-scale claims open, start trading and check the rate on pricing.