Call the tariff-rates API endpoint with a location_id to retrieve energy cost information (Tariff Rates) for any specified time period.

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Response data format

FlatPeak returns tariff rates as a time-series dataset, similar to a stock market feed. While this format may appear less efficient for flat-rate tariffs, it offers a universal integration format that future-proofs your implementation against changes in tariff structures.

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Units, precision and rounding

FlatPeak uses major currency units across all API endpoints, always returning tariff data with the highest available precision—currently up to 4 or 5 decimal places (e.g., EUR 0.12345). Implement rounding in your user interfaces. You can use this example as a reference.

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How often is data updated

Each response from the Tariff Rates API includes the next_update field, indicating when the tariff data may be refreshed from its source next. This could align with events like market rate publications or scheduled updates from the customer’s energy provider account. To ensure accuracy, we recommend using the next_update timestamp to schedule your system’s rate to refresh dynamically. If dynamic scheduling isn’t feasible, you can assume that rates for the following day will typically be updated by 23:00 local time the day before.

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How is daylight savings handled

When requesting tariff rates, ensure that both start_time and end_time are provided in RFC3339 format. This can be in Zulu time (UTC) (e.g. 2023-06-15T13:00:00Z) or with a time offset, (e.g. 2023-06-15T12:00:00+01:00). If you are using offsets and your request spans a period when daylight saving time begins or ends, ensure that both start_time and end_time reflect the correct time offset for the location. When you specify different time offsets, end_time takes precedence. This maintains consistency in the results. In the tariff rates response, the valid_from and valid_to times will all use the end_time offset that was applied. Example: 
{
    "request": {
        "start_time": "2025-03-30T00:00:00+01:00",
        "end_time": "2025-03-30T04:00:00+02:00"
    },
    "data": [
        {
            "valid_from": "2025-03-30T01:00:00+02:00",
            "valid_to": "2025-03-30T04:00:00+02:00",
            "tariff": {
                "confidence": 1,
                "rate": 0.02
            }
        }
    ]
}