A remote copper mine cut diesel fuel use by 64 percent and reduced unplanned process stops from fourteen to one per year after replacing a diesel-only supply with a hybrid solar microgrid built around a PV generator and a double-conversion UPS for its control loads. The result shows that off-grid industrial sites can retire most of their generator runtime without sacrificing reliability, provided the battery and the UPS are sized for the site's actual duty cycle rather than its nameplate peak.
The operation sits at 4,200 metres on a ridge with no grid connection within 200 kilometres. Three 1,200 kVA diesel gensets carried a base process load of about 480 kW, with a further 300 kW of motor inrush from the concentrator and the haul-truck workshop. Fuel arrived by road tanker on a 220 kilometre haul, and a single washed-out section of track could leave the camp short for days.
Reliability was the real cost, not fuel alone. Voltage excursions from genset load steps tripped the flotation controllers roughly fourteen times a year, each stop costing several hours of lost throughput on top of the restart sequence. Spare parts for the ageing gensets also had to be trucked in, so mean time to repair was measured in days rather than hours.
The retrofit paired a 2.4 MWp solar array with a 1.8 MWh lithium battery and two 60 kVA PV generator units drawn from the 10-60 kVA product range, backed by a 30 kVA online double-conversion UPS dedicated to the control and communications loads. A microgrid controller runs the solar first, the battery second, and the gensets only when state of charge falls below a set floor or throughput demand spikes.
Renewable penetration is capped at 80 percent so the gensets can always absorb surplus without hunting, and the battery carries the site through the 4 a.m. to 7 a.m. trough when the array is dark but the night shift is at full output. The PV generators handle the bulk of the daytime schedule, so the gensets now start cold only a few times a week instead of running continuously.
The UPS does not back the whole plant. It protects the load that must never blink: the distributed control system, the variable-frequency drives' logic, the communications radios and the safety interlocks. Those loads total about 22 kW, and a 30 kVA unit covers them with margin while the battery and the PV generators handle the heavy process draw.
This split is the key design choice. Trying to put a UPS in front of 480 kW of motors would have meant a vast, expensive inverter and a battery sized for minutes of full-load runtime. Protecting only the control layer with the UPS, and the process layer with solar plus battery, cuts both capital and the runtime requirement to something the battery can actually deliver.
Diesel displacement reached 64 percent in the best month and averaged 51 percent across the year.
Fuel spend fell from about 54,000 dollars per month to roughly 19,000 dollars, a saving near 420,000 dollars annually.
Genset run hours dropped from 720 to about 250 per month, extending overhaul intervals.
Unplanned process stops tied to power events went from 14 per year to 1.
Control-system uptime rose from 99.4 percent to 99.97 percent.
Carbon dioxide emissions from on-site generation fell an estimated 1,900 tonnes per year.
The one stop that remained came from a torn conveyor belt, not from the power system, which the operators counted as a clean result for the electrical side.
Three choices drove the outcome. First, the battery was sized to the duty cycle: modelling showed the site needed about ninety minutes of full process cover at the worst trough, not the four hours a nameplate rule of thumb would have suggested. Second, the PV generators were oversized relative to instantaneous demand so they could recharge the battery before the next trough. Third, the UPS was kept small and dedicated, which made the whole protection scheme affordable.
None of this required exotic hardware. The components are standard off-grid power products; the saving came from letting software decide when each source runs rather than running everything flat out.
Mines, telecom sites, border posts and remote pumping stations face the same maths: diesel is expensive and fragile, and the load that truly matters is often a fraction of the total. Carve out the critical control load, put a UPS in front of it, and let solar and batteries carry the rest. The payback is usually two to four years, after which the fuel saving is pure margin.
Sites already running a generator should start by metering the actual load profile for a month before buying anything. The profile, not the catalogue rating, should set the size of both the PV generator and the battery. Our hybrid solar-storage configurations are described at https://www.upsboss.com/solar-storage/, and the PV generator range that anchors this kind of build is listed at https://www.upsboss.com/products/.
Tell us your site's load profile, fuel cost and uptime target and our engineers will model a hybrid configuration with expected diesel displacement and payback. Browse the current range at https://www.upsboss.com/products/ or send your requirement through the contact form.
Key takeaway: an off-grid mine can cut diesel by more than half and nearly eliminate power-related stops by pairing solar and batteries for the process load with a small, dedicated UPS for the control load. Size from the real duty cycle, not the nameplate peak, and the economics close inside a few years.
Do we need a UPS if we already have a battery bank?
For the process load, often no. A battery and an inverter can carry it. But the control system needs the zero-transfer isolation of a double-conversion UPS so a genset step or a converter fault never reaches it, and that is where the UPS earns its place.
How big a PV generator should we start with?
Begin from a month of metered load data. Size solar to cover the daytime trough plus battery recharge, then size the battery to the worst overnight gap. Oversizing solar slightly is cheaper than undersizing the battery.
What happens during the rainy season?
The controller leans back on the gensets as solar falls, and the battery bridges the longer dark periods. The site never goes dark; it simply burns more diesel for a few months, which is exactly what the model budgets for.
Contact: Frank Zhang
Phone: +86-135 5688 8641
Email: frank@upsboss.com
Add: Jufeng Road, Guangming Street, Guangming District, Shenzhen City, Guangdong Province, China
