How We Delivered a 50MW Solar + 100MWh BESS Hybrid Microgrid for an African Mining Site
(Full Case Study)
Engineering a robust, cost-effective, and sustainable off-grid power system for a remote African mine — a turnkey Imax Power solution.
📋 Project Background & Requirements
A major mining group operating in a remote area of sub-Saharan Africa faced unsustainable energy costs and unreliable power. The mine was entirely dependent on diesel generator sets (gensets) with an average levelized cost of energy (LCOE) above $0.34/kWh. Fuel logistics were expensive and exposed to supply disruptions. Additionally, voltage/frequency fluctuations frequently caused unscheduled production stoppages, leading to millions in annual losses.
Imax Power was selected to design, deploy, and commission a 50 MW solar PV + 50 MW PCS + 100 MWh battery energy storage system (BESS) + diesel backup hybrid microgrid. The goal: maximize renewable penetration, guarantee >99.9% reliability for critical mining loads, enable full black-start capability, and reduce diesel consumption by over 70%.
⚙️ Core System Specifications
| Component | Technical Details |
|---|---|
| Solar PV Capacity | 50 MWp bifacial high-efficiency modules, sand-resistant coating, tilt optimized for equatorial high irradiance |
| Battery Energy Storage (BESS) | 100 MWh · BYD MC Cube-T series liquid-cooled, non-human-entry containers, IP55, integrated fire suppression |
| Power Conversion System (PCS) | 50 MW total (20 × 2.5 MW integrated PCS+MV skids), VSG, black-start, HVRT/LVRT |
| Diesel Gensets (existing + upgraded) | 3 × 8 MW as spinning reserve, automatic start/stop via EMS |
| Microgrid Architecture | AC-coupled, 33 kV common coupling bus, seamless islanding capability |
| Energy Management System (EMS) | Cloud + on-premise redundancy, AI-based load forecasting, real-time optimization |
| Thermal Management | Liquid cooling + dual-stage industrial dust filtration, rated for 45°C ambient |
⚠️ Key Challenges Faced in the African Mine
🔥 Extreme Heat & Heavy Dust
Site temperatures frequently exceed 45°C with airborne abrasive particles. Conventional air-cooled BESS would suffer from derating and accelerated cell degradation, threatening project ROI and reliability.
📉 Weak Grid / No Grid – Stability Risks
Original diesel-only system had voltage variations up to ±5% and poor frequency response. Large induction motors (shovels, crushers) caused severe voltage sags, leading to nuisance tripping. No rotating inertia from solar inverters.
⚡ Black-Start & Operational Resilience
The mine had zero black-start capability — a total outage would require external emergency generators and >8 hours of downtime, costing over $1M per event. The microgrid had to autonomously restart from complete blackout.
🌍 Carbon & ESG Pressures
Annual emissions of ~120,000 tCO₂ exposed the client to carbon taxes and reputational risks. The solution had to reduce diesel share to <15% of total generation.
🔧 Our Engineering Solution: Solar + Storage + Diesel Intelligent Integration
1. AC-Coupled Architecture — Why We Chose It
After evaluating DC vs AC coupling, we selected an AC-coupled microgrid to seamlessly integrate with existing diesel gensets and allow independent scaling of PV and storage. The 33 kV common bus connects all sources, providing high fault tolerance and easier future expansion. (Read our AC vs DC coupling guide for microgrids.)
2. Custom Liquid Cooling & Dust Protection
All 100 MWh BYD MC Cube-T containers feature liquid thermal management maintaining cell temperature difference ≤3°C even at 45°C. IP55 + industrial-grade dual filters keep dust out, ensuring full power availability without derating — a critical factor for mining environments. (Related: 5 common BESS cooling problems in hot climates and how we solved them.)
3. Smart PCS with VSG and Black-Start
Each 2.5 MW outdoor PCS + MV transformer skid incorporates Virtual Synchronous Generator (VSG) algorithm, delivering synthetic inertia and primary frequency control. The system maintains voltage regulation within ±2% under heavy load steps. Black-start is fully automated: BESS initiates grid formation, and within <20 minutes the entire mine is re-energized without diesel assistance.
4. Three-Tier Energy Management Strategy (Solar-First + Storage Shaping + Diesel Standby)
- Tier 1 – Solar priority: During daytime, PV supplies all loads; excess solar charges the BESS.
- Tier 2 – BESS dispatch: At night or during peak demand, batteries discharge, minimizing diesel runtime. The system also performs peak shaving and load shifting.
- Tier 3 – Diesel backup: Gensets automatically start only when BESS state-of-charge falls below 15% or during extreme prolonged cloudy periods. The EMS ensures the gensets operate at optimal efficiency.
The AI-enhanced EMS reduces diesel usage by over 72% while maintaining seamless power quality.
(Liquid-cooled)
(Black-start ready)
(Standby / Emergency)
📊 Project Results & Performance Data (12 months of operation)
| Metric | Actual Performance |
|---|---|
| Diesel consumption reduction | 72.3% (annual saving ~16.8 million litres) |
| System round-trip efficiency (PV+BESS) | 94.2% (including transformer losses) |
| Power reliability (SAIDI/SAIFI) | 99.94%, zero unplanned outages after commissioning |
| Renewable penetration (annual) | 76.5% (peak day >94%) |
| CO₂ emission reduction | ~47,000 tons/year, equivalent to 2.6M trees |
| Black-start time (full mine restoration) | < 18 minutes |
| Projected ROI (fuel savings + carbon credits) | 4.2 years |
| Battery calendar life / degradation | 15 years designed, first-year capacity fade ≤1.8% |
Beyond fuel savings, the mine eliminated voltage sags, improved equipment uptime by 8%, and created headroom for future expansion. Annual OPEX reduction exceeds $12M.
📌 Key Lessons Learned for Off-grid Mining BESS Projects
- Modularity is king: Containerized BESS and pre-assembled PCS skids reduced site installation time by 40%. The system is ready for future expansion to 80 MW solar + 200 MWh without major re-engineering.
- VSG is non-negotiable for high renewable penetration: Virtual Synchronous Generator technology provides synthetic inertia and damping, enabling stable 100% renewable operation and allowing large motor starts without frequency collapse.
- Liquid cooling + robust filtration pays back: In hot/dusty environments, liquid-cooled BESS maintains higher throughput and longer life, reducing O&M by 18% compared to air-cooled alternatives.
- Automated black-start must be fully tested: Our staged black-start sequence with EMS orchestration ensures the mine can recover autonomously, drastically reducing business interruption risk.
- Local training and remote support: We trained mine electrical teams and set up 24/7 remote monitoring, ensuring high system availability and rapid issue resolution.
These insights have been successfully replicated in subsequent mining microgrids across Africa and the Middle East, reinforcing Imax Power’s expertise in extreme-environment energy storage.
“Imax Power’s solar+storage+genset microgrid has transformed our energy landscape. Power quality now surpasses the national grid, and our diesel bill has dropped dramatically. This project sets a new benchmark for African mining, and we are already replicating it at two other operations.”
— Energy Director, Major Mining Group, 2024 Sustainability Report
🏭 About Imax Power
Imax Power is a global leader in industrial & off-grid microgrid solutions, specializing in solar-storage-diesel and solar-storage-charging systems. With over 300 MWh+ of BESS deployed in remote mines, islands, and harsh environments (Africa, Middle East, Southeast Asia), we provide full EPC and lifecycle services. Our engineering-first approach guarantees bankable ROI and energy independence.
📢 Start your microgrid journey today
For mining, industrial parks, or island grids — Imax Power offers a free feasibility assessment & preliminary ROI simulation. Our microgrid experts will respond within one week with a tailored concept design.
* Performance data based on 12-month on-site operational report. Imax Power reserves the right of final interpretation. For reproduction or media inquiries, contact marketing.
