# Solar irradiance meters

> Solar irradiance meters (pyranometers) that measure the sunlight reaching your panels, so the EMS can tell how much PV production to expect.

Source: https://voltmasters.io/en/docs/device-integrations/solar-irradiance-meters/

A **solar irradiance meter** (pyranometer) measures the solar irradiance reaching the plane of your PV panels, in **W/m²**. Our EMS uses this live measurement to estimate how much PV power the installation *should* be producing at that moment.

### Why add one

By comparing the measured irradiance against the actual production of a PV inverter, the EMS can:

-   Estimate the **achievable PV power** from the current sunlight.
-   Detect **curtailed or underperforming** production (for example, a string that is offline or soiled), because real production falls short of what the irradiance predicts.

The EMS learns an **irradiance-to-power curve** for each PV inverter that has an irradiance meter linked to it: over a rolling 30-day window it records the typical (median) power the inverter produced at each irradiance level, ignoring periods where curtailment was active. That curve is then used to judge live performance against the current irradiance.

### Linking to a PV inverter

An irradiance meter is added as its own device and then linked to a PV inverter through the inverter's **Solar Irradiance Meter** parameter in the device settings. One meter can be used as the reference for the inverter(s) it is linked to.

### Supported brands

Select a brand below for the supported models, or see the [Overview list](https://voltmasters.io/en/docs/device-integrations/overview-list/) for all supported brands and models.

-   [Soluzione Solare](https://voltmasters.io/en/docs/device-integrations/solar-irradiance-meters/soluzione-solare/)
-   [IMT Technology](https://voltmasters.io/en/docs/device-integrations/solar-irradiance-meters/imt-technology/)

Solar irradiance meters are **monitoring-only** devices: the EMS reads them but does not control them. They communicate over Modbus TCP.