powersync-docs/docs/appareils/tarifs/openmeteo.en.md

OpenMeteo

TESTING ETM CONSUMER

Get current weather data for your location.

The OpenMeteo plugin gives the box the weather and solar forecasts for your site: today's and tomorrow's weather, and the expected PV production for each roof orientation. The data come from the public Open-Meteo service, queried directly by the box — no account, no API key, and no detour through an ETM service.

Package: powersync-plugin-openmeteo.

1. What the plugin publishes

The plugin creates two kinds of objects:

• a site (Open-Meteo site): weather at the location (temperature, clouds, wind, humidity…), forecast solar irradiance, sunrise and sunset, and a satellite observation of the past hour;
• one or more PV planes (Open-Meteo PV plane), attached to the site — one per roof orientation. Each plane publishes the forecast irradiance on its modules and the expected production derived from it: for the current hour, the next 3, 6 and 12 hours, the rest of the day and tomorrow.

The energy engine adds up the planes of the designated site, and the app shows the resulting curve next to the measurements, with the hour-by-hour weather — see PV production forecast.

2. Adding the site

In installer mode, add an Open-Meteo site device (see Adding a device) and enter:

Field	Content
Latitude, Longitude	Position of the site, in decimal degrees
Elevation (m, optional)	Altitude of the site in metres. Optional: left at 0, Open-Meteo uses the altitude of its own terrain model. Enter it in mountains or narrow valleys, where the forecast temperature depends on it.

The site is not discovered automatically: it is created by hand, once per location.

3. Adding the PV planes

Once the site exists, add an Open-Meteo PV plane device: discovery offers one plane for each existing site. Create one plane per orientation — an east-west roof gives two planes.

Field	Content
Tilt (deg, 0=horizontal)	Tilt of the modules in degrees: 0 = flat, 90 = vertical
Azimuth (deg geographic, 180=South)	Orientation, in geographic convention: 180 = south, 90 = east, 270 = west
Peak power kWp	Peak power of the modules on this plane
Performance ratio (declared, not learned)	Overall system efficiency, declared by the installer (the box does not learn it). Left at 1.0, the expected production is overestimated.

Depending on the plugin version, two values from the module datasheet complete the plane: Power temperature coefficient (%/K, declared, not learned) (default −0.37 %/K) and NOCT (°C, declared, not learned) (default 45 °C). They correct the expected production when the modules heat up.

!!! warning "Mind the azimuth" Other tools count the azimuth from south (0 = south). Here, 0 is north: an azimuth of 0 entered for a due-south roof gives a heavily underestimated production forecast.

4. A forecast, never a measurement

Everything this plugin publishes is a weather forecast converted into production, or a satellite observation about an hour old. It is never a measurement of your installation: the actual production is read from the inverter or the meter.

This is why the values are named forecast… or observed… (satellite observation): there is no pvPower in this plugin, only forecastPvPower.

The expected production is a simple calculation: forecast irradiance × peak power × declared efficiency. It does not account for shading, soiled modules or, at plugin level, inverter clipping (the engine applies the inverter ceiling to the sum of the planes, if it has been entered). The error therefore always goes the same way: the forecast is optimistic. 4 kW forecast is not 4 kW produced.

The weather spread published for today and tomorrow (in %) says how uncertain the weather itself is. It says nothing about the accuracy of the expected production: on a clear, stable day it is low, precisely when the overestimate is at its highest.

5. Refresh and internet outage

Weather models do not publish more often than this: the forecast and the satellite observation are fetched every hour, the spread every 3 hours. The site's Refresh action forces all three.

If Open-Meteo does not answer, the plugin retries after 5 minutes, then 10, 20, 40… — never less often than the source's normal rate — and returns to its normal rate at the first answer. After 3 hours without a forecast, Forecast valid turns false.

An internet outage blocks nothing: the box keeps controlling with its measurements, safety is maintained, and only the forecasts degrade until the connection returns.

6. What leaves the box

To get its forecasts, the box sends Open-Meteo only:

• the site's coordinates, rounded to two decimals (about 1 km): precise enough for the weather, too blurred to point to an address;
• the site's altitude, if you entered it;
• the tilt and azimuth of each PV plane.

No measurement, no consumption and no usage data is sent. The peak power and the efficiency stay on the box: the conversion into production happens locally.

7. Commercial use: a dedicated Open-Meteo instance

The public Open-Meteo API is for non-commercial use only. For a commercial deployment, the plugin settings can point to a self-hosted Open-Meteo instance (Base URL (forecast), Base URL (satellite radiation), Base URL (ensemble spread)) or take a key for Open-Meteo's commercial offer (API key (commercial endpoint, optional)). Unchanged, the plugin queries the public API.

8. Data sources

Weather data by Météo-France, satellite radiation by EUMETSAT, provided through Open-Meteo under the CC-BY 4.0 licence.

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Reference

!!! info "Application labels" The keys and labels below are the ones the application shows, in English. They are left verbatim so that you find them word for word on screen.

Manufacturer: Open-Meteo
Plugin: OpenMeteo

Supported models

Model	Role	Transport	Pairing	Quantities
Open-Meteo site	weather, daylightsensor	—	Manual	29
Open-Meteo PV plane	—	—	Auto-discovery	15

Per-model detail

??? abstract "Open-Meteo site — openMeteoSite" Settings:

| Key | Label | Type | Range | Default | Read-only |
| --- | --- | --- | --- | --- | --- |
| `name` | Name | QString | — | — | no |
| `latitude` | Latitude | double | — | `48.9` | no |
| `longitude` | Longitude | double | — | `7.85` | no |
| `elevation` | Elevation (m, optional) | double | — | `0` | no |

_Measured quantities:_

| Key | Quantity | Type | Unit |
| --- | --- | --- | --- |
| `weatherDescription` | Weather description | QString | — |
| `weatherCondition` | Weather condition | QString | — |
| `updateTime` | Last update | int | UnixTime |
| `temperature` | Temperature | double | DegreeCelsius |
| `temperatureMin` | Minimum temperature (today) | double | DegreeCelsius |
| `temperatureMax` | Maximum temperature (today) | double | DegreeCelsius |
| `humidity` | Humidity | int | Percentage |
| `pressure` | Pressure | double | HectoPascal |
| `windSpeed` | Wind speed | double | MeterPerSecond |
| `windDirection` | Wind direction | int | Degree |
| `cloudiness` | Cloudiness | int | Percentage |
| `snowfall` | Snowfall (preceding hour) | double | CentiMeter |
| `forecastGhi` | GHI forecast (W/m²) | double | — |
| `forecastDni` | DNI forecast (W/m²) | double | — |
| `forecastDhi` | DHI forecast (W/m²) | double | — |
| `terrestrialRadiation` | TOA radiation (W/m2) | double | — |
| `forecastGhiSumToday` | GHI sum forecast today (kWh/m²) | double | — |
| `observedGhi` | GHI observed, satellite (W/m²) | double | — |
| `observedClearSkyGhi` | Clear-sky GHI observed, satellite (W/m²) | double | — |
| `observedClearSkyIndex` | Clear-sky index kt (observed) | double | — |
| `sunriseTime` | Sunrise time | int | UnixTime |
| `sunsetTime` | Sunset time | int | UnixTime |
| `daylight` | Daylight | bool | — |
| `forecastModel` | Forecast model that answered | QString | — |
| `forecastValid` | Forecast valid | bool | — |
| `forecastTendencyToday` | Sky tendency forecast today | QString | — |
| `observedTime` | Satellite sample time | int | UnixTime |
| `forecastIssuedAt` | Model run initialisation — revision key | int | UnixTime |
| `forecastAvailableAt` | Model run publication — informational, never a revision key | int | UnixTime |

??? abstract "Open-Meteo PV plane — openMeteoPvPlane" Settings:

| Key | Label | Type | Range | Default | Read-only |
| --- | --- | --- | --- | --- | --- |
| `name` | Name | QString | — | — | no |
| `tilt` | Tilt (deg, 0=horizontal) | double | 0–90 | `30` | no |
| `azimuth` | Azimuth (deg geographic, 180=South) | double | 0–360 | `180` | no |
| `kwp` | Peak power kWp | double | — | `0` | no |
| `performanceRatio` | Performance ratio (declared, not learned) | double | 0.1–1.0 | `1.0` | no |

_Measured quantities:_

| Key | Quantity | Type | Unit |
| --- | --- | --- | --- |
| `forecastGtiSource` | GTI forecast, source quantity (W/m²) | double | — |
| `updateTime` | Last update | int | UnixTime |
| `forecastPvPower` | PV power forecast | double | Watt |
| `forecastEnergyNext3h` | PV energy forecast, next 3 h (rolling, may cross midnight) | double | KiloWattHour |
| `forecastEnergyNext6h` | PV energy forecast, next 6 h (rolling, may cross midnight) | double | KiloWattHour |
| `forecastEnergyNext12h` | PV energy forecast, next 12 h (rolling, may cross midnight) | double | KiloWattHour |
| `forecastEnergyRestOfDay` | PV energy forecast, now until sunset | double | KiloWattHour |
| `forecastEnergyTomorrow` | PV energy forecast, tomorrow | double | KiloWattHour |
| `forecastPeakTime` | Forecast peak irradiance time today | int | UnixTime |
| `observedGti` | GTI observed, satellite (W/m²) | double | — |
| `observedGtiTime` | Satellite sample time | int | UnixTime |
| `forecastWeatherSpreadTodayPercent` | GTI weather spread today — qualifies weather only, not PV accuracy | double | Percentage |
| `forecastWeatherSpreadTomorrowPercent` | GTI weather spread tomorrow — qualifies weather only, not PV accuracy | double | Percentage |
| `forecastSpreadModel` | Ensemble model used for spread | QString | — |
| `forecastCurveTransport` | Forecast curve — transport channel, not a value | QVariantMap | — |