Australia’s National Electricity Market (NEM) recorded a combined 4,780GWh of solar generation in September 2026, comprising 1,805GWh from utility-scale assets and 2,975GWh from rooftop systems.
Analysis of data sourced from Open Electricity (formerly OpenNEM) shows that the combined figure represents a 22.8% increase from August 2026’s 3,893GWh total and a 21.5% rise year-on-year from September 2025’s 3,933GWh.
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The result extends the recovery documented in the August NEM Data Spotlight, which found combined generation climbing 17.3% from July, as utility-scale solar rose 12.4%, posting the widest year-on-year growth margin recorded since the winter trough.
It marks the strongest September in the three-year dataset, comfortably ahead of September 2024’s 3,439GWh and last year’s total.
Utility-scale solar at 1,805GWh rose 10.9% from August’s 1,628GWh and was 36.9% above September 2025’s 1,319GWh, the widest year-on-year growth margin recorded for the segment since the recovery began.
The total is the highest monthly figure since February 2026’s 1,836GWh, continuing the broadly upward trajectory that has characterised the dataset since combined generation fell 21% in June amid an end-of-month pricing spike that pushed utility-scale prices above AU$120/MWh.
Rooftop solar at 2,975GWh climbed 31.3% from August’s 2,265GWh and was 13.8% higher than September 2025’s 2,614GWh. The total is the highest recorded since January 2026’s 3,464GWh, with the segment’s growth rate now comfortably outpacing utility-scale on a month-on-month basis, a reversal from the pattern through most of winter.
The result is broadly consistent with the trend flagged in last year’s equivalent entry in this series, which found solar generation surging 18% as Australia entered spring, with lengthening daylight hours compounding the continued addition of rooftop capacity across the NEM.
Daily generation data for September show a pattern distinct from August’s rally into month-end, with the month’s strongest stretch arriving mid-month rather than in the closing days.
Output over the first four days was held within a relatively narrow band, with utility-scale generation ranging from 54GWh to 62GWh and rooftop generation from 89GWh to 95GWh. Conditions deteriorated sharply on day five, when utility-scale output fell to 41GWh, the lowest reading of the month. At the same time, rooftop generation held comparatively steady at 89GWh, suggesting localised cloud cover was affecting utility-scale assets more directly than the more geographically dispersed rooftop fleet.
Generation rebuilt through the second week, climbing to 68GWh on day 11 and 66GWh on day 12 for utility-scale, before a second, shallower dip to 50GWh on day 13.
From day 14 onward, both segments entered a sustained rally that peaked between days 17 and 20, the strongest stretch of the month for both technologies. Utility-scale output reached 72GWh on day 17 and 75GWh on day 18, the month’s high point, while rooftop generation climbed in parallel, reaching 120GWh on days 18 and 19 before peaking at 122GWh on day 20, also the month’s high point for the segment.
Generation moderated through the back half of the month without approaching the mid-month peaks again.
The final ten days produced utility-scale readings mostly in the mid-50s to mid-60s GWh range, with day 26 recording the lowest rooftop total of the second half at 85GWh, alongside a moderate 63GWh from utility-scale the same day.
Unlike August, which closed with four consecutive record daily highs, September’s strongest days arrived around the middle of the month, a pattern consistent with the transitional nature of early-spring generation profiles before the longest days of the year compound further with capacity additions later in the season.
Pricing across September averaged approximately AU$23.90/MWh (US$16.81/MWh) for utility-scale solar and AU$13.90/MWh for rooftop on a simple daily basis, both considerably below August’s averages of roughly AU$34.90/MWh and AU$31.70/MWh, respectively, even as generation rose sharply across both segments.
The month’s clearest pricing feature was the frequency of negative rooftop pricing. Rooftop solar recorded a negative daily average on ten of September’s 30 days, a marked increase from August, when a single negative pricing event on day two was flagged as the first of the winter dataset, reversing the absence of negative pricing noted across the July Spotlight.
The deepest negative readings coincided directly with the month’s strongest generation days: rooftop pricing fell to -AU$13.97/MWh on day 19 and -AU$19.22/MWh on day 20, the lowest of the month, as rooftop output simultaneously reached its September peak of 122GWh. Utility-scale pricing turned negative only once, reaching -AU$2.63/MWh on day 19, the sole such reading in the dataset.
A separate and more pronounced pricing episode emerged across days 21 to 25, when utility-scale prices climbed above AU$44/MWh on every day and peaked at AU$70.22/MWh on day 23, the month’s highest reading.
Unlike the negative pricing cluster around days 19 and 20, this spike did not coincide with unusually low generation; utility-scale output across the five days ranged from 59GWh to 65GWh, close to the monthly average, suggesting the pricing pressure stemmed from demand-side conditions rather than a supply shortfall.
You can explore previous solar generation performance in our NEM Data Spotlight series, with all entries available to PV Tech Premium subscribers.

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