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The ePowerBay Curtailment Ranking solution organizes generation curtailment data to make it easier to compare plants and generating groups monitored by ONS, Brazil's national power system operator.

The tool helps identify developments with the highest share of curtailed generation during the selected period. Use the ranking to investigate regional differences, compare assets and direct more detailed analyses of generation and connection conditions.

Define your search scope

Use these filters:

• State: select the region you wish to analyze.

• Generation Source: choose EOL for wind power or UFV for solar photovoltaic generation.

• Start Month and End Month: define the period used in the calculation.

To analyze a single month, select the same month in both fields. For a broader assessment, choose a range.

Click Search to generate the list. Results initially appear from highest to lowest curtailment percentage.

Understand the indicators

The table provides:

• Ranking Position: classification by curtailment percentage within the selected scope.

• ONS Identifier and Name: identify the plant or generating group.

• Curtailment Percentage: curtailed energy as a share of generated energy plus curtailed energy.

• Curtailment in MWh: curtailed generation recorded during the period.

• Generation in MWh: electricity generated during the same period.

• Associated Substation: shows the available connection to grid infrastructure.

The percentage is calculated using totals for the period:

Curtailment Percentage = Curtailment ÷ (Generation + Curtailment) × 100

For example, a development with 20,000 MWh curtailed and 80,000 MWh generated has a curtailment percentage of 20%.

For multi-month ranges, the calculation uses accumulated volumes rather than a simple average of monthly percentages.

Compare percentage and volume

The percentage helps assess the relative intensity of curtailment. The MWh volume shows the amount of energy curtailed.

A development can have a high percentage but a lower curtailed volume than a larger asset. Examine both indicators together and use the same period when comparing results.

Ranking position also depends on the selected filters. A classification for a particular state or generation source must be interpreted within that scope.

Explore the development and its connection

Where a link is available, click the plant or generating group name to open its information page.

The associated substation name also lets you explore the infrastructure. Combine this query with margins, connected projects and works presented in Basic Grid Substations.

This sequence provides context for the results. Association with a substation alone does not identify the cause of all curtailment.

Organize results and export data

Use Columns to choose displayed information. Click headers to sort by percentage, curtailed volume or generation, according to your comparison objective.

Adjust the number of records per page and use pagination to explore additional results.

Under Exports, Search Results lets you take query data into your analyses and reports. Export page exports the records on the displayed page.

A practical example

To compare solar developments in a state, select the region, UFV and your preferred period.

Review the highest percentages, compare curtailed volumes and open the most relevant developments. Then explore their substations for connection information.

Repeat the query for another period while keeping region and source filters unchanged to observe changes in indicators and rankings.

Interpret history in context

The ranking describes available data for the selected period. It is neither a forecast of future curtailment nor, on its own, a financial assessment of developments.

Consider record coverage and differences in how long assets have operated. Use the results to select cases for further investigation.

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