Replacing diesel generators at a remote mine with solar and batteries

A remote mine that makes its own power with diesel pays for it every single day. The fuel is bought at the terminal, trucked in over long roads, stored on site and burned in engines that keep running whether the mill needs all of them or not. When the oil price jumps, the power bill jumps with it. In September 2026, Brent crude averaged US$116.8 a barrel, against US$90.9 in August, according to the World Bank. A site that runs on diesel has no way to hedge that inside its own fence.

Solar and batteries take most of that exposure out. Not all of it, and not in one step.

What solar replaces, and where it stops

Solar panels only make power in daylight. On a mine that runs around the clock, that sets a ceiling.

Sandfire’s DeGrussa copper-gold mine in Western Australia was one of the first to prove the point. In June 2016 a 10.6 MW solar plant with a 6 MW / 1.8 MWh battery was connected to the site’s 19 MW diesel station. It offset about 5 million litres of diesel a year, up to a fifth of what the site burned. The battery was small on purpose. Its job was to keep the diesel grid stable when clouds passed over the panels, so fewer engines had to idle as backup.

That is the first step. Solar saves fuel during the day, and a short battery keeps the system steady.

What the battery adds

The second step is to switch engines off for hours at a time. That takes a bigger battery, and inverters that hold the site grid’s voltage and frequency themselves, a job the running engines used to do. Bellevue Gold in Western Australia showed what that looks like. Its hybrid power station, with 27 MW of solar, 24 MW of wind and a 15 MW / 33 MWh battery, ran for 155 hours in a row in 2026 with every engine off.

The third step is to cover the night. Now the battery is measured in hours, not minutes. At Kamoa-Kakula in the DRC, CrossBoundary Energy’s plant of 233 MWp of solar and 526 MWh of batteries started commercial operation on 12 August 2026. It gives the copper mine 30 MW of firm power around the clock.

Size it from the fuel, not from the land

The usual mistake is to size the solar field to the land you happen to have and the battery to the budget. Start at the other end. How many litres do you burn, and in which hours?

Our work model sizes the battery for the hours the site has to get through after the sun goes down. It starts at 12 hours of night cover. Battery capacity in kWh is the average load times those hours, divided by 0.9 for the part of the battery you can actually use. A site with an average load of 5 MW that wants 12 hours of cover comes out at about 5 × 12 ÷ 0.9 ≈ 67 MWh. That shows how the formula works. It is not a design.

Keep the engines. Some diesel almost always stays on site, for long cloudy spells, maintenance and emergencies. The aim is that they run as insurance, not as the base of the system.

Own the plant, or buy the power

There are two ways to pay, and both are in use at working mines. B2Gold owns the solar and battery plant at its Fekola gold mine in Mali. DeGrussa, Bellevue and Kamoa buy their power from an independent producer that owns the plant.

GoSí offers both:

Own & operate. The client buys and owns the system.

Land + PPA. The client provides the land, our partners build the plant, and the client buys the power under a power purchase agreement.

Owning gives you every litre saved, and puts the asset on your balance sheet. A PPA moves the capital to the producer, who will price your remaining mine life into the tariff and the length of the contract.

What the numbers can look like

On our home page we show a modelled estimate for a 10 MW solar and battery plant at a remote gold mine: fuel cost 42% lower in the first year. With the work model’s default diesel case of 2,000 litres a day at US$1.10 a litre, payback comes out at about 3.5 to 5.4 years. These are model outputs, not results from a GoSí plant. Your own fuel price, load and mine life will move them.

How we work with a mine

GoSí does not build plants itself. We bring the pieces together:

Feasibility. A first look at the site, the load, and whether a plant fits the operation.

Procurement partners. The partners who supply and build the equipment.

Available subsidies. The subsidies that apply to the project.

Green mine finance. Finance for the plant, under either way of owning the power.

Custom design. Our EPC partners design and build the plant for your load, land and conditions.

To start, send us a year of fuel invoices, the site’s hourly or daily load, the expected mine life and a map of the land near the power station. With that, the work model gives a first answer on battery size and payback.