fronius-solarapi

Async Python library for the Fronius Solar API, the JSON interface of Fronius Datamanager, Datalogger Web, Symo Hybrid and GEN24/Tauro/Verto devices. Built on aiohttp.

Supports both API versions:

• v1 (/solar_api/v1/) — every Datamanager 2.0, Symo Hybrid and GEN24/Tauro/Verto device
• v0 (/solar_api/) — first generation Datalogger Web and Datamanager 1.0; only inverter, logger and active device requests exist there

The highest version a device supports is detected on the first request, as the spec describes: a device without GetAPIVersion.cgi serves v0.

Requests

Every request returns a Response[T] with the common response head (timestamp, status, request arguments) and the typed data:

System scope results and the active device info are keyed by the device id the device reports (the Solar Net address, "1" on GEN24).

All models are frozen dataclasses. Measurements are float | None in the base unit of the API (W, VA, VAr, Wh, VArh, V, A, Hz, °C, percent), kept as int where the device reports a number without fraction; codes are int | None; flags are bool | None. None means the device did not report the value. Lookups for the codes are included: InverterInfo.model and PowerFlowInverter.model resolve the device type table of the spec, InverterInfo.state and DeviceStatus.state the inverter status codes, MeterData.meter_location the meter location codes and OhmpilotData.state the Ohmpilot state codes. Battery states are decoded as the spec describes: StorageModule.cell_state and previous_cell_state for Fronius Solar Battery modules, and StorageController.state for LG Chem RESU H and BYD Battery-Box controllers. The known string values of power flow mode, battery mode, meter location, secondary meter category, Ohmpilot and Ohmpilot Eco states and LED color/state are available as StrEnums for comparison.

Errors

All errors derive from FroniusError:

• FroniusConnectionError — the device is unreachable or did not answer in time
• InvalidResponseError — the answer is not a valid Solar API response (non-JSON, missing header, wrong types)
  • EndpointNotFoundError — HTTP 404; GEN24 devices answer every request this way while the Solar API is disabled in their web interface
• NotSupportedError — the request does not exist on the API version served (e.g. meters on v0); raised before anything is sent
• StatusError — the response header carries a non-zero status code, with code, reason, user_message and the parsed head
  • RequestNotSupportedError — the device reported code 11 (NotSupported) or code 255 with a "not supported" reason, as older firmware does for e.g. storages on devices without one; also a NotSupportedError

Datamanagers reach inverters, meters and storages over Solar Net, whose requests fail now and then (about 1 % of inverter requests on Symo devices end in LNRequestTimeout). Answers with the status codes 7, 8 and 9 (Solar Net request error, timeout and parse error) are therefore repeated up to status_retries times (default 2) after retry_delay seconds (default 0.5). Every other status code, connection errors and timeouts are raised right away; backing off from an unreachable device is left to the caller.

Usage

import aiohttp

from fronius_solarapi import FroniusSolarApi, NotSupportedError

async with aiohttp.ClientSession() as session:
    api = FroniusSolarApi(session, "192.168.0.10")

    inverters = (await api.inverter_info()).data
    for device_id, inverter in inverters.items():
        data = (await api.inverter_common_data(device_id)).data
        print(inverter.custom_name, inverter.model, data.power_ac, "W")

    try:
        flow = (await api.power_flow()).data
    except NotSupportedError:
        print("no power flow on this device")
    else:
        print(flow.site.power_grid, flow.site.power_load, flow.site.power_photovoltaics)

The connection lifecycle stays with the caller. GEN24 firmware 1.35 and later redirects requests from non-private IP addresses to HTTPS with a self-signed certificate; a session for such a device needs SSL verification disabled. Requests are limited to two in parallel per client, as the spec asks for, and time out after 10 seconds by default (timeout=).

scripts/dump.py <host> prints everything a device reports.

Fronius quirks handled

• GetLoggerInfo.cgi puts its body under Body.LoggerInfo, every other request under Body.Data.
• Datamanagers HTML-escape CustomName, CashCurrency and CO2Unit, GEN24 devices send plain UTF-8.
• A negative UTCOffset is reported as unsigned 32 bit integer.
• GEN24 devices encode integers and flags as floats ("Visible": 1.0, "CodeOfState": 0.0).
• GEN24 firmware before 1.13.5 reports the inverter state string as StatusCode.
• ErrorCode -1 means no valid error code.
• A GEN24 Primo was seen reporting "DeviceStatus:" (trailing colon) in the cumulation collection.
• GEN24 devices answer Scope=System inverter requests with Value instead of Values, and list their inverters at the top level of the active device info instead of inside Inverter.
• Some GEN24 firmware reports meter channels under internal names (SMARTMETER_*, ACBRIDGE_*).
• The power flow Version is an integer within a string, and absent on old Datamanagers.
• API v0 names the device parameter DeviceIndex and has no system scope for active devices, so one request per device class is made.
• The content type of responses is not checked, as some devices send text/javascript.

Development

uv sync
uv run pytest
uv run ruff check . && uv run ruff format --check . && uv run mypy fronius_solarapi tests scripts

Recorded device responses live in tests/fixtures. The sets symo, gen24, gen24_storage, igplus_v2 and primo_s0 are shared with the Home Assistant integration, datamanager_v0 and datamanager_v1 come from pyfronius and spec_listings from the examples in the official specification. Every request is snapshotted against every set with syrupy.

Acknowledgements

This library replaces pyfronius by Niels Mündler and Gerrit Beine, whose handling of device quirks it inherits.