Electricity + Control January 2019

ENERGY MANAGEMENT + ENVIRONMENTAL ENGINEERING

lar’s Proving Ground near Tucson in Arizona. “We were able to visit this and see for ourselves the system in operation. As far as I’m aware, we’re the first company in the world to deploy it in a mining application.” The engineering, procure and construction (EPC) contract to deliver the solar farm was award- ed to Barloworld Namibia in June last year. Shortly after B2Gold received the necessary environmen- tal approval from Namibia’s Ministry of Environ- ment &Tourism, debushing and ground levelling of the 22 ha site started. The first shipment of solar panels arrived on site at the end of October and the first PV module was installed on 1 November. Construction of the solar farm was completed by late February 2018 and in early March the power- line exporting energy to the HFO plant was ener- gised successfully. On 14 May the MMC and its associated SCADA system, the ‘brain’ of the sys- tem, was commissioned. Comments Roos: “The project was complet- ed on schedule and within its budget of N$ 115 Million or US$8,5 million. We’re particularly proud of the fact that a total of 105 000 man hours was worked without a single LTI incident and that the Namibian content of the project was maximised, both in terms of procurement and construction.” He adds that many members of the construction team were trainees sourced from the Namibian In- stitute of Mining &Technology (NIMT). The completed solar farm comprises 62 400, 115-W CAT-branded thin-film solar panels, manu- factured by its joint venture partner First Solar, Inc,

which has its headquarters in Arizona. The panels are mounted on a PiA single-axis tracking system. The DC power is converted to AC power through Sunny tri-power three-phase SMA string inverters and is then distributed to the HFO plant via Schnei- der switchgear in the PV control building through a 3,5 km overhead powerline. According to Roos, the CAT-branded thin-film panels have a specific yield advantage over tradi- tional polycrystalline panels in hot conditions and have a superior shading response. The solar farm has a modular design, allowing PV energy to be added to (or removed from) the Otjikoto microgrid in 1 MW increments. In integrating the solar farm with the HFO plant to create a hybrid power system, the MMC works in conjunction with the HFO plant’s SCADA sys- tem, developed in a collaborative effort between the Barloworld/Caterpillar technical team and Na- mibian-owned IAE, which specialises in industrial automation and engineering. Explaining how the MMC works, Roos says it not only regulates the energy being fed to the HFO plant but allows for the seamless selection of the mine’s two energy sources (HFO or solar), choosing the most economically viable option at any point in time. “Most importantly, the MMC enables the mine to switch off one of its HFO gen- erators during day-time based on algorithms mon- itoring irradiance, cloud cover and PV penetration,” he states. “This not only allows us to save HFO but also reduces the operating hours on our large HFO gensets.”

"The project was completed on schedule and within its budget."

30 Electricity + Control

JANUARY 2019