Cat microgrid to provide solar power solution

CM3606 A011916Cat solar microgrid helping to power the Otjikoto gold mine in Namibia. (Image source: Caterpillar)Barloworld Equipment has installed a Cat solar microgrid ready to power the Otjikoto gold mine in Namibia in 2018 

The 7MWp solar field will help power the gold mine, 300km north of Windhoek, Namibia's capital, on behalf of precious metals exploration company B2Gold.

The microgrid will help offset the cost of running the mine’s existing diesel-powered Cat generators.

"A microgrid is any small grid that interconnects sources of electricity and loads. In this case, the source is solar and our load is the Otjikoto mine. When complete, we'll have 256 groups each with 240 photovoltaic

(PV) panels covering about 14 ha," said Francois-Xavier Saury, regional business development manager for Caterpillar.

It is estimated the grid will save 3.8 million litres of heavy fuel oil, reducing genset operation by 3,170 hours – a saving of nearly US$2mn per year.

"The idea behind installing solar is not to increase power, but to offset the cost associated with fuel consumption and generator maintenance," said Cobus van Schalkwyk, head of power solutions for Barloworld Equipment.

"The system also uses more than 250 x 25kW string inverters. The inverters change power from direct current (DC) to alternating current (AC).

Utilising small inverters mean that should one go down for any reason, we are only losing 25kW of power at any one time," said Saury.

Running the whole system is the Cat Master Microgrid Controller (MMC), an advanced technology suite for multiple energy sources. The system makes cost management, electricity storage and monitoring the entire system seamless for the customer.

Power beyond the mine

The Cat PV panels are guaranteed for 25 years. However, it is unsure whether the mine will be active that long. "If B2G's operation stops after 10 years, the PV panels will have at least another 15 years of life,” said Francois-Xavier.

"One of the post closure options that B2Gold is investigating is to use the solar field together with the generators to generate power and feed that into the national grid. This will ensure that the legacy of B2Gold remains long after the closure of the mine," said Cobus van Schalkwyk.

"And, I think it's also important to note that when B2Gold first began constructing the mine, they already had a couple of spare electrical incomers in their main switchgear labelled 'PV field'. So, they were somewhat visionary," added Francois-Xavier. "They knew that at some point in the future, solar would be a game-changer. And, that time is now."

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