Summary
The week from Sunday 13 September to Friday 18 September averaged about 25.8 GW of measured generation, with renewables averaging 48.3% of measured output. The strongest renewable day in the available data was Friday 18 September, when wind, solar and hydro together averaged 65.3% of measured generation. Gas was highest on Monday 14 September and lowest on Friday 18 September.
For flexible electricity use, the cleanest opportunities are likely to appear when wind is strong, gas is low and demand is not at a peak. This is the foundation for future EV-charging guidance, clean-electricity alerts and weekly newsletter summaries.
The reporting period in key numbers
| Average measured generation | ~25.8 GW across available settlement-period aggregates |
|---|---|
| Average renewable share | 48.3% |
| Highest renewable share | 65.3% on Friday 18 September |
| Highest average wind output | ~14.8 GW on Friday 18 September |
| Highest average solar output | ~3.0 GW on Tuesday 15 September |
| Highest average gas output | ~10.0 GW on Monday 14 September |
What the reporting-period figures show
- Renewables were strongest on Friday 18 September, when wind, solar and hydro averaged 65.3% of measured generation.
- Wind was the largest swing factor in the available feed, peaking at about 14.8 GW average output on Friday 18 September.
- Solar was strongest on Tuesday 15 September, averaging about 3.0 GW across settlement periods after embedded-solar backfill where needed.
- Gas averaged about 6.4 GW across the period, rising highest on Monday 14 September and falling lowest on Friday 18 September.
- Measured generation was highest on Thursday 17 September, at roughly 28.0 GW average output.
Renewable and gas comparisons — not carbon rankings
Best low-carbon proxy: Friday 18 September
Historical carbon-intensity aggregates are not yet part of this weekly report feed, so EnergyMix.info uses renewable share and gas output as cautious proxies. Friday 18 September had the strongest renewable share at 65.3%.
Lowest gas proxy: Friday 18 September
Gas generation averaged about 3.6 GW on Friday 18 September. Lower gas periods are often cleaner, but the report does not yet claim this was the lowest-carbon period without historical carbon-intensity validation.
Higher gas output — not a carbon measurement
Highest gas proxy: Monday 14 September
Gas averaged about 10.0 GW on Monday 14 September. Gas-heavy periods are usually higher-carbon, but this is labelled as a proxy until historical carbon-intensity highs/lows are added to the report feed.
Wind, solar and gas highlights
Wind
Highest average wind output was about 14.8 GW on Friday 18 September.
Solar
Highest average solar output was about 3.0 GW on Tuesday 15 September.
Gas
Highest average gas output was about 10.0 GW on Monday 14 September; lowest was about 3.6 GW on Friday 18 September.
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Data notes
Compiled by Energy Mix from Elexon generation data and NESO embedded-generation estimates. Energy Mix calculates the totals, averages and comparisons shown here. Source data may be revised. Source attribution does not mean that Elexon or NESO has reviewed or endorsed this report.
Sources: Elexon Insights FUELHH; NESO Historic GB Generation Mix; NESO Demand Data Update. These datasets can share underlying observations; agreement is not independent certification.
Renewable-share and gas-output comparisons are not measurements of carbon intensity. See data sources and methodology for source information. A report-specific reproducible evidence pack was not preserved for this publication.
Original publication introduction and methodology note
A measured weekly report for EnergyMix.info using the available 7-day historical generation feed for Sunday 13 September to Friday 18 September.
This report is generated from the available 7-day historical generation feed and validated against external public data. Carbon-intensity highs/lows and interconnector summaries should be treated as future additions unless they are present as validated historical aggregates.
Preserved as part of the original publication. Any broad validation wording in this note should not be read as proof that all reporting days or narrative claims were checked.
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