500kW Hybrid PV-Diesel-BESS All-in-One Cabinet with +4×40kW ACDC Modules – Zambia Copper Mine Microgrid
Project Background & Requirements
A large open-pit copper mine in Zambia’s Copperbelt province, located over 180 km from the national grid, relied entirely on diesel gensets (6×500kW units) consuming ~2,800 liters of diesel per day. Annual fuel costs exceeded $1.8M, with rising carbon penalties and frequent price volatility. The mine aimed to deploy a highly resilient solar-storage-diesel microgrid with renewable penetration ≥45%, while also preparing for future electric mining trucks and DC drilling equipment.
After detailed site audits, we proposed a 500kW hybrid string-type all-in-one BESS cabinet with integrated PCS, MPPT, EMS, fast transfer switch (PCM), AC/DC distribution, diesel genset controller, and surge protection. On top of the standard 160kW ACDC module, the customer required four additional 40kW ACDC modules (total DC-coupled power 320kW) to support DC fast charging and multi-cluster batteries.
Key Challenges We Faced
1. Extreme Dust & High Ambient Temperatures
Yearly average 32°C, peak surface temperature above 45°C, with heavy copper ore dust. Traditional air-cooled storage suffers from frequent filter clogging and component lifespan reduction.
2. Multi-Cluster Battery Imbalance & Circulating Currents
The customer planned four battery clusters (different batches, total 2MWh). Conventional centralized PCS cannot handle cluster-level SOC balancing, causing the “wooden barrel effect” that wastes usable capacity.
3. PV Fluctuation & Off-Grid Frequency Stability
Rapid irradiance changes demand grid-forming capability and fast load response. The system must coordinate with diesel gensets to avoid low-frequency load shedding.
4. High-Power DC Fast Charging Requirement
The mine plans to introduce 12×90kW e-trucks and DC drills within three years. The initial 160kW ACDC capacity was insufficient; a scalable DC bus expansion was critical.
Our Engineering Solution
System Architecture Design
We engineered a string-type modular all-in-one cabinet integrating a 500kW bi-directional PCS, 6 MPPT trackers, EMS, PCM static transfer switch, AC/DC distribution, genset auto-sync, and type C surge protection. To meet the DC expansion needs, we added four independent 40kW ACDC modules (hot-swappable) on the DC bus, raising total DC coupling capacity to 320kW.
Active SOC Balancing & Cluster-Level Intelligent Management
Our PCS and BMS deeply cooperate via active SOC balancing algorithm that reads each cluster’s SOC/SOH in real time. This eliminates the “wooden barrel effect” and allows mixing of different battery batches. Usable capacity over lifetime increased by 23%.
10ms Seamless Transfer & Diesel Hybrid Grid-Forming
The PCM static switch combined with solid-state relays achieves transfer time ≤10ms. During an unexpected grid loss, critical loads continue operation without any interruption. Fuel savings reached 62% compared to diesel-only operation.
Integration of Four Additional 40kW ACDC Modules
The cabinet came with pre-engineered DC expansion slots. Four 40kW modules are parallel-controlled with active current sharing, each with independent cooling and hot-swap capability. Round-trip efficiency reaches 98.5%.
Technical Specifications – 500kW Hybrid Cabinet
| Parameter | Value / Feature |
|---|---|
| Rated AC Power | 500kW (1.2x overload for 60s) |
| DC Voltage Range | 600V ~ 1500V |
| MPPT / Max Efficiency | 6 independent MPPT, efficiency ≥99.0% |
| Modular String PCS | 10×50kW hot-swappable modules, N-1 redundancy |
| Transfer Time (grid to island) | ≤10ms (load zero-perception) |
| Extra ACDC modules | 4×40kW bi-directional, efficiency ≥98.5%, hot-plug |
| Battery cluster input | 4 independent clusters, active SOC balancing |
| Protection / Cooling | IP54, intelligent fan + self-cleaning dust filter |
| Operating Temp | -25°C to +55°C |
Project Results & Performance Data
Commissioned in March 2025, the system has operated reliably for 9+ months.
- Overall system efficiency reached 96.7%
- Active SOC outcome: max SOC deviation reduced from 12% to 2.8%
- Power reliability: 210 consecutive days off-grid without outage
- ACDC module utilization: 1,750kWh daily DC charging
Key Lessons Learned
1. Modularity is the cornerstone for long-term microgrid reliability
String-type modular architecture ensures mine production online even if a single module fails.
2. Cluster-level SOC balancing + EMS synergy exceeds expectations
Integrated strategies keep all clusters in optimal zones, delaying battery replacement.
3. DC coupling is the inevitable trend for mine electrification
Reserve at least 30% DC expansion slots in initial designs to avoid retrofits.
Contact Us
Imax Power – Specialized Microgrid & BESS Solutions Provider
String-type hybrid cabinets | Mine & industrial microgrids | Energy storage
+8613760212825
Contact us for a one-on-one project consultation | Global support
