Entry · Operation
Energy load
How much energy does the interconnected system serve per day?
Acronyms: ONS, National Electric System Operator.
In one sentence
Load served in the interconnected system, published by the ONS by subsystem on a daily basis, in MWavg; what goes into the figure changed in March 2021 and in April 2023.
Real example
On Sep 28, 2026, the load of the SIN, the sum of the four subsystems, was 88,896 MWavgNature of the data: Calculated.
No Check this number record of its own in this example: the number comes from the panel's published database, which carries the source and the reference date.
Calculated: Deterministic transformation made by Scrutiniums, with a published formula.
Why it matters
How it is measured
In MWavg, by subsystem and day. Until February 2021, load served by plants dispatched or scheduled by the ONS; from March 2021 to April 2023, the forecast of plants not dispatched is added; from the date the ONS declares, Apr 29, 2023, the estimate of distributed micro and mini generation is added, made with forecast weather data.
Unit: MWavg, by subsystem and day
Not to be confused with
Load is the energy served; centralized generation is the energy produced by the plants in the ONS balance. In each subsystem, generation minus load should correspond to the interchange; the Grid balance shows the hours when it does not.
They are the same ONS product at different granularities: the average of the 24 hours of the curve reproduces the load of the day. The curve shows the hour-by-hour profile; the daily load does not.
What cannot be concluded
- Comparisons that cross Mar 1, 2021 or the inclusion of MMGD are not homogeneous.
- In the published data, the step from the inclusion of MMGD appears on May 1, 2023, not on the declared date (Apr 29, 2023); Apr 29 and 30, 2023 are excluded from the comparisons.
- MMGD is inside the load, but the ONS does not publish it separately in this dataset.
Related entries
See in the panel
Official source
ONSOpen data portal, dataset “Carga de Energia Diária” (dataset description, accessed on Oct 1, 2026)
In other words: what the load includes changed twice; since Apr 29, 2023, according to the ONS, it includes an estimate of distributed micro and mini generation made with weather forecasts.
Literal excerpt from the document
Portuguese only“Até fevereiro/2021, os dados representam a carga atendida por usinas despachadas e/ou programadas pelo ONS, com base em dados recebidos pelo Sistema de Supervisão e Controle do ONS. Entre março/2021 e abril/23, os dados representam a carga atendida por usinas despachadas e/ou programadas pelo ONS, com base em dados recebidos pelo Sistema de Supervisão e Controle do ONS, mais a previsão de geração de usinas não despachadas pelo ONS. A partir de 29/04/2023, além dos dados anteriormente considerados, passou a ser incorporado o valor estimado da micro e minigeração distribuída (MMGD), com base em dados meteorológicos previstos.”
Documents accessed and text checked on Oct 1, 2026.