NEM Data Spotlight: Solar Generation Falls, Prices Spike
The National Electricity Market (NEM) has seen a significant drop in solar generation in June, with combined solar generation falling 21% from the previous month. This decline is consistent with the seasonal pattern observed during winter transitions. The data, sourced from Open Electricity, reveals a 58% reduction in generation from December 2025's peak to June 2026, mirroring the winter trough of June 2025. While weather conditions in June 2026 were comparable to the previous year, the decrease in rooftop solar output is notable, falling 13.1% year-on-year.
One thing that immediately stands out is the impact of weather conditions on solar generation. June's generation totals aligned with prior-year seasonal norms, suggesting that weather conditions were not particularly adverse. However, the year-on-year growth rate of 6.3% in June is the weakest recorded, reflecting the inherent solar resource constraints during winter and the relatively stable comparable June 2025 figure.
What makes this particularly fascinating is the contrast between utility-scale and rooftop solar generation. Utility-scale solar generation reached its lowest monthly total since June 2025, yet it remained 6.3% above that prior-year figure, highlighting the continued expansion of large-scale capacity. Conversely, rooftop solar output fell 13.1% year-on-year, an unusual reversal of the upward trend observed over the past two years.
In my opinion, this highlights the importance of considering both the scale and the distribution of solar generation. While utility-scale solar has seen significant growth, the decline in rooftop solar output warrants attention. This could be attributed to a combination of cloud cover, reduced irradiance, and the distributed nature of rooftop generation, which plays a crucial role in offsetting localised demand peaks during grid stress periods.
The pricing data for June reveals a month that ended under materially different market conditions than those prevailing at its opening. Average daily prices for both utility-scale and rooftop solar were broadly contained below AU$90/MWh through the first three weeks of the month, with several days recording averages below AU$50/MWh. However, from day 21 onwards, prices began a sustained climb that accelerated sharply through the final week, with rooftop pricing crossing the AU$100/MWh threshold on day 22.
If you take a step back and think about it, this pricing pattern reflects the low-wind period that affected South Australia toward the end of June, driving spot prices higher across the NEM as dispatchable capacity was called upon to compensate for reduced renewable energy output. The end-of-month price spike is less severe than the event that defined May 2026, but it represents a more prolonged period of elevated prices than May's sharper single-day event.
A detail that I find especially interesting is the absence of negative pricing in June. Unlike February 2026 during the summer peak, negative pricing was absent from the June dataset entirely, consistent with the pattern observed in April and May. This absence is consistent with winter demand patterns, where heating load sustains consumption through the middle of the day, preventing the excess generation conditions that characterise summer and spring afternoons.
In conclusion, the NEM's solar generation and pricing dynamics in June offer valuable insights into the market's seasonal shifts and the interplay between generation and demand. As the renewable energy generation mix shifts with the seasons, the NEM's pricing behaviour has been characterised by episodes of volatility at both extremes, with summer negative pricing giving way to winter scarcity events. This highlights the importance of understanding the market's seasonal patterns and the impact of weather conditions on solar generation and pricing dynamics.
