Shumen Water Pumping Station Off-Grid Project, Bulgaria
- Location: Shumen, Bulgaria
- Configuration: PCS + 6 × E-MATE 125-261-L
- Capacity: 1,566kWh
- Application: PV+Storage
- Year: 2026
Project Overview
Situated in the middle of farmland in Shumen, Bulgaria, this irrigation station operates in pure off-grid mode with no access to the power grid. It previously relied on diesel generators that ran around the clock, incurring millions in fuel and maintenance costs — a burden compounded when diesel prices nearly doubled within a few months.
In 2026, EENOVANCE delivered a 1,566 kWh PV-storage microgrid at the site, integrating six E-MATE 125-261-L battery cabinets (261 kWh each) with the plant's pre-installed PV array and Huawei 2 × 100 kW on-grid inverters. The cabinets operate in parallel under a master-slave configuration, powering irrigation pumps rated up to 90 kW.
EENOVANCE's BESS solution was adopted as a strategic approach to cutting operating costs while minimizing the facility's carbon footprint.
Challenges
Zero-Grid Fallback: The site operates completely isolated from the utility grid, leaving zero safety net for power deficits during extended periods of low renewable generation.
High Inrush Current & Black-Start Demand: Heavy motor loads (water pumps) generate massive inductive surge spikes, risking inverter over-current trips during start-up without grid inertia.
Severe Seasonal Solar Variance: Extreme drops in solar irradiance during spring and autumn demand a delicate balance between PV oversizing, battery bank autonomy, and operational cost.
Grid-Forming Frequency & Voltage Control: The system must act as a 100% grid-forming voltage source, maintaining phase balance and voltage stability under rapidly dynamic, unbalanced loads.
Solution
1. System Configuration
| Component | Details |
| PV Array | Installed PV modules + Installed PV inverter |
| On-grid Inverter | Installed Huawei, 2 × 100 kW |
| Liquid Cooling Battery Cabinet | E-MATE 125-261-L × 6 · Total 1,566 kWh |
| Battery Parallel Junction Box | EENOVANCE-Developed Core Component |
- The system adopts an off-grid topology.
- The PV inverter and the energy storage system are both connected to the 400 V AC bus.
- The EMS coordinates and schedules the entire system.
- This configuration forms a stable PV-plus-storage microgrid.
2. Key Technical Innovations: PCS Update and Working in Grid-Forming
EENOVANCE R&D engineers specialize in Power Conversion System (PCS) upgrades, grid-forming control, and off-grid microgrid stabilization, with a proven track record in implementing Virtual Synchronous Generator (VSG) algorithms, parallel inverter synchronization, and seamless firmware updates for mission-critical energy storage systems. They are adept at transforming grid-following assets into stable, autonomous grid-forming voltage sources with full black-start capability.
| Module | Key Technical Points |
| 1. PCS Maintenance & Upgrades | Modular hot-swappable updates, Modbus/IEC 61850 protocol migration, firmware flashing, rollback protocols |
| 2. Grid Forming Mode | Virtual Synchronous Generator (VSG) logic, P/f and Q/V droop algorithms, synthetic inertia, dynamic frequency/voltage regulation |
| 3. Microgrid Operations | Multi-unit parallel load sharing, circulating current mitigation, black-start sequencing, transformer inrush management |
| 4. Testing & Validation | Hardware-in-the-Loop (HIL) simulation, DSP control loop tuning, system Factory Acceptance Testing (FAT) |
Outcomes & Benefits
Post-expansion operation confirms all performance targets have been met, resolving long-standing power supply constraints at the water plant.
1. Cost Reduction
- Predictable ROI: Fuel independence stabilizes long-term costs and hedges against energy market volatility.
- Fast Payback: Fuel and maintenance savings typically recoup the investment within 3–5 years of continuous operation.
- Automated Demand Management: Soft-start ramping powers heavy pumps cleanly, reducing mechanical wear and peak-power stress on motors.
2. Stability & Reliability
With six battery cabinets operating in parallel, the system delivers 20+ hours of continuous full-load backup. All pumps, filtration units, and control systems run uninterrupted, ensuring zero-downtime water supply, eliminating emergency-response costs, and protecting infrastructure from pressure surges.
3. Environmental and Social Value
- Decarbonization: Replaces diesel with solar and LFP storage, cutting CO₂ and particulate emissions.
- Soil & Water Protection: Eliminates fuel-leak and spill risks during transport, storage, and refueling.
- Economic Stability: Stabilizes operating costs and shields communities from fuel-price spikes and rate hikes.
- Local Capability Building: Trains local engineers on advanced grid-forming storage technology.
Diesel generator start-ups are down ~90%, saving several tons of CO₂ annually with far lower noise. Increased PV consumption strengthens the plant's ESG profile and supports green-subsidy and certification applications in Bulgaria.
Feedback from our client
"Transitioning our water infrastructure to this grid-forming solar and storage solution has completely transformed our operations. With six parallel E-MATE cabinets running seamlessly alongside the updated PCS, we survived a recent extended outage with zero pump downtime and over 20 hours of continuous full-load backup — without touching a drop of diesel. The elimination of generator noise and fuel logistics has been a massive win for our field team, and our operating costs have plummeted. It's rare to find an engineering solution that delivers this level of reliability, environmental value, and immediate ROI."
— the owner of Alfa Comers, Bulgaria
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