SunSat™, Reuniwatt’s reliable satellite-to-irradiance technology, is based on the regular high-resolution earth observation provided by geostationary satellites, and delivers accurate local irradiance data for any location – worldwide. It can be used in two different ways:

  • SunSat™ live: As a real-time monitoring service available for any site or portfolio of solar installations on the planet.
  • SunSat™ time series: As a service to retrieve historical irradiation time series, for any site on the planet.

Hardware-free solution

Hardware-free solution

No matter the number of solar plants in your portfolio, SunSat™ enables you to get a precise estimation without installing any hardware.

World coverage thanks to 5 geostationary satellites

World coverage thanks to 5 geostationary satellites

Reuniwatt receives the live images of five geostationary satellites, enabling an irradiance estimation service anywhere in the world.

Accurate and reliable data

Accurate and reliable data

SunSat™ provides accurate and reliable data for already monitored or unmonitored PV plants. Beyond 25 km, ground measurements are less precise than satellite data.


SunSat™ is a methodology which uses geostationary meteorological satellites to estimate solar irradiance. Images provided by the visible channel of the satellite sensor can be converted into global horizontal irradiance (GHI) maps with a proven accuracy.
SunSat™ benefits of constant improvement to increase the accuracy of the data provided. It is based on an original technique eveloped by Reuniwatt (Cros et al., 2015) and derived/optimised from the work developed about 15 years ago the Mines Paristech under the direction of Lucien Wald, made by Rigollier et al. (2004) and Cros et al. (2004).


  • Global coverage

  • Time resolution: 10 to 15 minutes depending on location

  • Easy data access via our API

  • For a single site or a portfolio of PV installations

Ask for more information

SunSat™ services

SunSat™ Live: real-time irradiance and weather data

The use of satellite data for real-time estimation in a purpose of monitoring offers many advantages compared to sole in-situ measurements:

  • Unbiased and independent vision of the estimated irradiance over a plant or a portfolio of installations
  • Quick detection of any instrumental failure or soiling by comparing actual power generation and satellite estimation
  • Immediate and affordable set-up (no hardware needed)
  • Larger field of view (macroscopic vision vs microscopic vision)

SunSat™ Time Series: historical irradiance and weather data

The use of historical satellite data is crucial within the first phases of a solar project. Irradiance time series are necessary to:

  • Optimally size and design solar power plants
  • Realise technical and financial studies for due diligence
  • Reassure investors through bankable data
More info

Obtain PVsyst compatible data

Reuniwatt on PVsyst website

You might also be interested in

SunSat™ Digital Twin, the health-check tool for solar assets

Download our white paper “Monitoring and improving remote assets”

Irradiance data for project development