One of the world’s largest off-grid solar-storage hybrid projects is under construction, at the Fekola Mine in Mali. A complete solar forecasting system implemented by Reuniwatt will allow to efficiently plan the generator dispatching and to mitigate the risk of solar production variability for the US$ 38million microgrid project.

Improving fuel savings with short-term solar forecasts for microgrids

Hybrid energy systems combining solar and storage with diesel or HFO (heavy fuel oil) fuelled gensets are ideal to provide a stable energy supply for remote mining operations, and counteract the high costs of fuel supply by using the locally available renewable resources. At the Fekola Mine, the gold producer B2Gold Corp. approved the addition of a 36 MWp solar plant along with 17 MW battery storage capacity to the existing thermal power plant, which will save about 13 million litres of HFO per year. The mine is thus becoming one of the first industrial sites of this scale in West Africa to move towards a more sustainable energy supply.

In order to handle the variability of solar irradiance levels and generated solar energy, a cutting-edge solar forecasting system will also be implemented at the site. Such a tool is essential to optimise the use of the generated solar power, charge the batteries when possible, and use the available gensets only when necessary in order to minimise the costs. The forecasting system, that will be provided by France-based Reuniwatt, will continuously provide forecasts of the PV plant’s power output, using data from a locally installed high-class sky camera and advanced satellite-to-irradiance technology. Suntrace together with its partner BayWa r.e. were selected to support B2Gold during implementation of the project as solar experts. The storage system will be based on Wärtsilä’s energy management solution.

Large scale off-grid projects profit from sky imagers

The project will rely on different types of solar irradiance and production forecasts. These include forecasts retrieved from satellite data and weather models for the coming hours, allowing for efficient planning of generator dispatching. In addition, highly accurate forecasts for the next 30 minutes will be provided by Reuniwatt’s robust infrared sky imager Sky InSight™, aiming to send warnings for unexpected cloud events and start additional HFO generators if need be.
Sky InSight™ uses an infrared vision technology for unprecedented accuracy in day & night cloud detection. It can operate off-line, which is important within remote microgrids suffering from occasional weaknesses in their communication network. With a minutely update frequency, Reuniwatt’s sky camera can forecast sudden drops of solar radiation within the next 30 minutes. With this information, actions can be taken in time to ensure a stable power supply and avoid blackouts. The use of sky cameras enables optimised battery (dis-)charging and genset controls, ensuring a safe power supply for industrial operations relying on hybrid power plants with a maximum solar share.

Solar forecasting allows for significant cost savings through improved power reliability for largescale off-grid projects. At Reuniwatt, we have a decade of experience with industrial-grade solar forecasting. Solar and battery storage hybrid projects are the future of energy supply for remote sites, as they allow operations to become cheaper and more sustainable. We are proud to bring in our experience and work together with our prestigious partners on this first-of-its-kind installation in southwest Mali” explains Nicolas Schmutz, CEO of Reuniwatt.

It is a strong commitment by B2Gold to build such a significant solar-battery plant as a fuel saver for the Fekola mine. This project is a landmark solution, combining a significant solar energy share with highest security in the overall power supply. The solution is an intelligent combination of Photovoltaic, a large battery system, and Reuniwatt’s sophisticated solar forecasting service that harmonizes the solar power generation with the existing HFO engines. We highly appreciate that B2Gold has entrusted Suntrace together with BayWa r.e. as expert to support the implementation of this innovative project.” says Boris Westphal, CEO of Suntrace.

A webinar presenting Suntrace and Reuniwatt’s feedbacks on off-grid projects was organized on September 3rd. It is possible to watch the webinar on demand through the following link.
Also, more information about Reuniwatt’s sky camera and short-term forecasting solutions can be found here:

Webinar on Demand
More information about InstaCast™ service

About Reuniwatt (
Reuniwatt is a major player of the solar radiation and cloud cover assessment and forecasting. Based on solid Research and Development works, the company offers reliable products and services intended for professionals of various fields, making the best out of two key facets of the meteorology: atmospheric physics and data sciences. A particular focus has been placed on solar energy forecasting, while developing cutting edge solutions to improve the short-term prediction of the solar resource.
The company has won many grants, including H2020’s SME Phase 1 programme, which makes Reuniwatt a European Champion with regard to innovation. Reuniwatt has also been selected among the national fast-growing companies to join the prestigious French Tech 120 programme in January 2020.

About Suntrace GmbH (
Suntrace GmbH, established in 2009, is an independent expert for solar energy and storage projects, developing innovative energy solutions for its clients covering all major technologies from photovoltaics to solar thermal power and energy storage, finding the most economical solution. Suntrace is actively supporting the energy transition in established and emerging economies. Suntrace customers are from industry, finance and institutions and the track record covers more than 100 projects in over 40 countries, totaling about 7 GW of capacity. Since 2019, Suntrace has become an independently operating member of the Dornier Group; Dornier Group offers comprehensive infrastructure engineering services for the energy, water, mobility and aviation sectors.