Following a tender for solar energy forecasting services in 2019, Reuniwatt has been one of the selected service providers. Reuniwatt’s solar irradiance forecasts will allow grid operator Terna to safely increase the PV share in Italy’s national grid, where around 10 GWp of new solar capacity are expected by 2023.

Forecasting necessary for a successful energy transition in Italy

Reuniwatt is a market leader in forecasting solutions and will provide solar production forecasts for all of Italy’s regions for the upcoming days. Reuniwatt’s solar energy forecasts help minimize risks and ensure the successful integration of more solar energy into the national grid.
Reuniwatt has developed advanced algorithms adapted to various landscapes and climatic zones, that allow the advanced analyses of data derived from geostationary satellites, and consequently carry out irradiation and solar production forecasts, based on the cloud movement. Reuniwatt’s proprietary method HourCast™ anticipates the clouds’ trajectory thanks to the treatment of several successive images, allowing to anticipate the cloud cover at a specific location and subsequently to deliver highly accurate solar power forecasts for the coming hours. Reuniwatt’s DayCast™ will permit grid operators to access nationwide forecasts of a very high temporal and spatial resolution for the next days. Both services will be provided for predefined areas. Thanks to forecasting technology it will be possible to safely manage system operations and achieve greater photovoltaic penetration in Italy’s national grid without compromising grid stability.

The producer and consumer model of distributed generation for renewable sources is changing Italy’s energy market: It has resulted in the growth of “active” solar energy resources connected to the grid. In order to maintain a high level of observability of the grid in terms of injections and withdrawals of energy, forecasts are an essential tool, both on production and demand side, and allow Terna to safely manage the available resources. Advanced forecasts are part of the innovative data management and analytics required to help mitigate the risks associated with the management of renewable sources.

“We are very happy to accompany Italy’s energy transition process and work with our high-profile customer Terna. Thanks to solar energy forecasting, financial risks caused by solar energy variability can be controlled and the renewables share can be increased safely.” explains Reuniwatt CEO and Founder Nicolas Schmutz.

About Reuniwatt (
• Reuniwatt specialises in solar forecasting as well as in solar irradiance and power assessment. It provides solutions and technologies to massively and securely inject photovoltaics into the grid.
• Reuniwatt develops solutions destined to key solar energy players: project developers, plant and grid operators, monitoring and asset management solution vendors, energy traders.
• The company has won many grants, including H2020’s SME Phase 1 programme, which makes Reuniwatt a European Champion regarding innovation.
• Reuniwatt has also been selected among the national fast-growing companies to join the prestigious French Tech 120 programme in January 2020.
• Reuniwatt has offices in Reunion Island (HQ), Paris and Toulouse.

About Terna (
• Terna SpA is a transmission and system Operator from Rome, Italy, guaranteeing a secure quality national electricity system with more than 74,400 kilometers of high voltage lines, as well as ensuring operating efficiency, grid integration and digital transformation.
• Playing a key role in energy transition, Terna is responsible for grid development, the growing integration of renewables into the national grid, and progressive decarbonisation.
• With more than 4200 employees, Terna derives more than 90% of its revenue from regulated market activities in Italy, but also engages in non-regulated market and international activities.
• Terna has achieved hight ranks in several of the most important sustainability indices for the stock markets, such as Euronext vigeoeiris and Dow Jones Sustainability Indices.