Installation

We use uv to manage dependencies. First, install uv.

Then add it to your project:

uv add flexmeasures-client

The FlexMeasures Client can also run as an S2 CEM. To enable S2 features, you need to install extra requirements:

uv add flexmeasures-client[s2]

Initialization and authentication

To get started with the FlexMeasures Client, first an account needs to be registered with a FlexMeasures instance. To create a local instance of FlexMeasures, follow the FlexMeasures documentation. Registering to a hosted FlexMeasures instance instead can be done through Seita BV.

In these examples we show how to set up the client to connect to either http://localhost:5000 or https://ems.seita.energy. To connect to a different host, adapt the host in the initialization of the client.

from flexmeasures_client import FlexMeasuresClient

async def main():
    client = FlexMeasuresClient(host="localhost:5000", ssl=False, email="email@email.com", password="pw")
    client = FlexMeasuresClient(host="ems.seita.energy", ssl=True, email="email@email.com", password="pw")

Retrieving available info

Retrieve user and account:

user = await client.get_user()
account = await client.get_account()

The data will be returned as a dictionary.

Retrieve available assets and sensors:

assets = await client.get_assets()
sensors = await client.get_sensors()

The data will be returned as (lists of) dictionaries.

Sending data

Post a measurement from a sensor:

await client.post_sensor_data(
    sensor_id=1,
    start="2023-03-26T10:00+02:00",  # ISO datetime
    duration="PT6H",  # ISO duration
    values=[1, 2, 3, 4],  # list
    unit="kWh",
)

Here is a small but complete FlexMeasures Client script, which simply updates the flex context of an asset:

import asyncio

from flexmeasures_client import FlexMeasuresClient

usr = "xxxxxxxxxxxxxxxx"
pwd = "xxxxxxxxxxxxxxxx"
asset_id = 1


async def main():
    client = FlexMeasuresClient(email=usr, password=pwd)

    asset = await client.update_asset(
        asset_id=asset_id,
        updates={
            "flex_context": {
                "site-consumption-capacity": "110 kW",
                "relax-constraints": True
            }
        },
    )

    print(asset)

    await client.close()


asyncio.run(main())

For a slightly larger self-contained script, see this script for sending data. It sets up an asset and sensor (checking if they exist first), and then sends data to it using post_sensor_data().

Scheduling

With FlexMeasures a schedule can be requested to optimize at what time the flexible assets can be activated to optimize for price of energy or emissions.

The calculation of a schedule can take some time. On FlexMeasures v0.33.0 and newer, the convenience method waits on the generic job-status endpoint before retrieving the schedule values. It falls back to result-endpoint polling on older servers.

Trigger and retrieve a schedule for multiple devices:

schedules = await client.trigger_and_get_schedule(
    asset_id=3,
    start="2026-09-05T08:00+02:00",
    duration="PT12H",  # ISO duration
    flex_context={
        "consumption-price": {"sensor": 7},
    },
    flex_model=[
        # Example flex-model for an electric truck at a regular Charge Point
        {
            "sensor": 8,
            "power-capacity": "22 kVA",
            "production-capacity": "0 kW",
            "soc-at-start": "50 kWh",
            "soc-max": "400 kWh",
            "soc-min": "20 kWh",
            "soc-targets": [
                {"value": "100 kWh", "datetime": "2026-09-05T18:00+02:00"},
            ],
        },
        # Example flex-model for curtailable solar panels
        {
            "sensor": 9,
            "power-capacity": "20 kVA",
            "consumption-capacity": "0 kW",
            "production-capacity": {"sensor": 9},
        },
    ],
)

For triggering and retrieving a schedule for a single device, simply limit the flex-model to list a single device. Alternatively, use a single-device flex-model (no list) and move the device’s power sensor ID out of the flex-model and use it as the sensor ID in the call to trigger_and_get_schedule (and leave out the asset ID).

schedule = await client.trigger_and_get_schedule(
    sensor_id=8,
    start="2026-09-05T08:00+02:00",
    duration="PT12H",  # ISO duration
    flex_context={
        "consumption-price": {"sensor": 7},
    },
    flex_model={
        "soc-at-start": "50 kWh",
        "soc-max": "400 kWh",
        "soc-min": "20 kWh",
        "soc-targets": [
            {"value": "100 kWh", "datetime": "2026-09-05T18:00+02:00"},
        ],
    },
)

The trigger and get schedule function can also be separated to trigger the schedule first and later retrieve the schedule using the schedule_uuid.

Trigger a schedule:

schedule_uuid = await client.trigger_schedule(
    **kwargs,  # same kwargs as previous example
)

The trigger_schedule method returns a schedule_uuid. On FlexMeasures v0.33.0 and newer, wait for the job once before retrieving one or more sensor results:

await client.wait_for_job(schedule_uuid)

schedule = await client.get_schedule(
    sensor_id=8,
    schedule_id=schedule_uuid,
    duration="PT45M",  # ISO duration
)

For the complete scheduling API, including multi-device results, job timeouts, and compatibility with older servers, see scheduling.

Forecasting

Trigger a forecast for a sensor and wait for the result:

forecast = await client.trigger_and_get_forecast(
    sensor_id=1,
    duration="PT24H",  # ISO duration – how far ahead to forecast
)
# Returns e.g. {"values": [1.2, 1.5, ...], "start": "...", "duration": "PT24H", "unit": "kW"}

On FlexMeasures v0.33.0 and newer, the client polls the generic job endpoint until the forecasting job is complete, then retrieves its values. For more advanced options (training window, regressors, forecast frequency, etc.) see forecasting.

Development

We use uv to manage dependencies. First, install uv.

To install the package with all development and testing dependencies:

uv sync --group dev --group test

Moreover, if you need to work on S2 features, you need to install extra dependencies:

uv sync --extra s2 --group dev --group test

Making Changes & Contributing

Install the project locally (creating a virtual environment automatically):

uv sync

Running tests locally is crucial as well:

uv run poe test

For S2 features:

uv sync --extra s2 --group test
uv run poe test-s2

This project uses pre-commit, please make sure to install it before making any changes:

uv tool install pre-commit
cd flexmeasures-client
pre-commit install

It is a good idea to update the hooks to the latest version:

pre-commit autoupdate

Don’t forget to tell your contributors to also install and use pre-commit.

New releases on PyPI are made by adding a tag and pushing it:

git tag -s -a vX.Y.Z -m "Short summary"
git push --tags

(of course you need the permissions to do so)

See releases in GitHub Actions at https://github.com/FlexMeasures/flexmeasures-client/deployments/release