Solar Forecasting System for Fekola Mine’s 36MWp Solar-Battery-Hybrid Project in Mali


Improving fuel savings with short-term solar forecasts

Hybrid energy systems combining solar and storage with diesel or HFO (heavy fuel oil)-fueled gensets are ideal to provide a stable energy supply for remote mining operations and counteract the high costs of fuel supply by using locally-available renewables resources. At the Fekola Mine, the gold producer B2Gold Corp approved the addition of a 36 MWp solar plant along with 17 MW of battery storage capacity to thermal power plant at the site, which will save about 13 million liters 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 optimize the use of the generated solar power, charge the batteries when possible and use the available gensets only when necessary, in order to minimize 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 of unexpected cloud events and start additional HFO generators if need be.

Sky InSight™ uses an infrared vision technology for unprecedented accuracy in day and night cloud detection. It can operate off-line, which is important within remote locations suffering from occasional weaknesses in their communication network. With a minute by minute update frequency, Reuniwatt’s sky camera can forecast sudden drops of solar radiation within the subsequent 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 optimized battery charging and discharging and genset control, 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 large scale off-grid projects,” said Reuniwatt CEO Nicolas Schmutz. “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.”

Suntrace CEO Boris Westphal said: “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.”