ONS forecasts a 4,9% increase in load, and PLD skyrockets in the free market.

The ONS (National Electric System Operator) has raised its forecast for energy load growth in the SIN (National Interconnected System) to 4,9% in October, compared to the same month in 2025.

The revision mainly reflects the higher temperatures observed in several regions of the country in the second half of the month, a scenario that reinforces the pressure on meeting demand during peak hours.

The estimate is included in the PMO (Monthly Operation Program) for the week of October 17-23, released by the operator on Friday the 16th. The forecast corresponds to an average load of 86.358 MWmed in the SIN (National Interconnected System).

Regionally, the largest increase is expected in the Northeast, with a rise of 11,8%, followed by the North, with 10,3%, and the Southeast/Central-West, with 3,5%.

For the South, the estimate is a reduction of 0,8%. The numbers show that the expected increase in demand is not distributed evenly across the country, posing distinct challenges to the operation of the system.

The ONS review is taking place in a context where the combination of heat, variations in renewable generation, and the concentration of consumption in certain periods can increase the cost of meeting the load.

On Thursday the 15th, this dynamic appeared prominently in the energy market, with the PLD (Price of Settlement of Differences), a benchmark for negotiations in the free market, rising rapidly at the end of the afternoon and reaching one of the highest levels predicted for the day.

A 2.400% increase in just a few hours.

According to data from CCEE (Chamber of Electric Energy Commercialization), the PLD reached R$ 1.437/MWh on Thursday, after remaining at the floor of R$ 57,31/MWh for part of the day.

The climb began around 16 PM, accelerated during the afternoon, and reached its peak at 19 PM. Considering the extremes recorded, the variation was approximately 2.409% in a single day.

The increase was mainly attributed to two simultaneous movements. There was a decrease in wind power generation in the Northeast and an increase in demand in other Brazilian regions. This combination reduced the available supply precisely during peak consumption hours, requiring the activation of more expensive thermoelectric power plants.

Wind power generation in the Northeast region of Brazil was expected to be approximately 3 GW below the level observed on Wednesday the 14th, according to data from CCEE. The explanation given was cloud cover associated with the passage of a cold front over the region.

At the same time, the load forecast for 19 PM indicated an increase of approximately 3 GW in the SIN (National Interconnected System). The reduction in supply and the increase in demand therefore occurred in similar proportions and during the same critical period of operation.

Operating costs also skyrocket.

Another indicator that tracked market movements was the CMO (Marginal Cost of Operation), which represents the cost of meeting the additional demand on the electrical system.

The indicator started the day at R$ 0 and went on to exceed R$ 1.500/MWh between 18 PM and 20 PM, according to information from ONS. The increase in the CMO coincided with the period in which the PLD advanced most sharply.

The reduction in solar generation at the end of the day also helps to contextualize price behavior. With the loss of photovoltaic production in the late afternoon, the system needs to increase the contribution of other sources to keep up with the so-called load ramp, the period in which consumption begins to increase.

During this period, the need for additional resources can increase the marginal cost, especially when the availability of other renewable sources also decreases.

Thursday's episode combined higher peak demand with lower wind power contribution in the Northeast and the need to resort to more expensive thermal generation.

This trend may repeat itself.

According to CCEE, fluctuations of this type may occur again at this time of year, under the influence of the El Niño phenomenon.

Meanwhile, the ONS (National System Operator) states that it continuously monitors the evolution of load and service conditions, paying special attention to periods of peak demand.

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