1. Project Overview
This project is deployed on a remote island in the Philippines, where there is no public utility grid. Conventional local power supply fully relies on diesel generators, which bring multiple drawbacks including high cross‑sea fuel transportation costs, loud operating noise, heavy exhaust pollution, complicated maintenance and unstable power output, restricting power security for local production and daily‑life loads. To fundamentally improve island power supply conditions, a custom‑built standalone off‑grid photovoltaic‑energy‑storage system is adopted for this project.
Taking full advantage of abundant solar irradiation on the island, the solution combines high‑efficiency monocrystalline PV generation and large‑capacity lithium‑iron‑phosphate energy storage. It implements the operating logic: self‑consume on‑site PV power in daytime, store surplus energy in batteries, and supply loads from energy storage at night, delivering stable and clean power for island‑based equipment, residential consumption and production loads around the clock. Targeting the harsh tropical island conditions featured by high temperature, high humidity, heavy salt spray and frequent typhoons, all equipment is specified with industrial‑grade outdoor anti‑corrosion, humidity‑resistant and typhoon‑proof configurations to support long‑term unattended reliable operation.
2. Overall System Configuration
The complete system adopts self‑developed and self‑manufactured core devices. The full bill‑of‑materials is listed below:
High‑efficiency monocrystalline PV modules: 590W × 60 units; total PV installed capacity: 35.4kWp
MPPT solar charge controller: 192V 100A × 2 units (operated in parallel)
Three‑phase power‑frequency off‑grid inverter: 30kW, DC 192V input, 60Hz output compatible with Philippine local grid standard
Outdoor lithium‑iron‑phosphate energy storage cabinet: 16kWh per unit × 4 units connected in parallel; total usable energy capacity: 64kWh
Rated peak power: 590W
Maximum‑power voltage: 42.7V
Maximum‑power current: 13.82A
Open‑circuit voltage: 51.6V
Short‑circuit current: 14.65A
Dimensions: 2384×1134×30mm
Ingress protection: IP68
Operating temperature: ‑40℃ ~ +85℃
3.2 192V 100A MPPT Solar Charge Controller (2 units in parallel)
System rated DC voltage: 192V
Charging current per unit: 100A
Max combined charging current (2‑unit parallel): 200A
MPPT operating voltage range: 240V‑450V DC
Conversion efficiency: ≥99%
Charging algorithm: 3‑stage smart charging: bulk / absorption / float charge
Communication: RS485 Modbus for remote monitoring
Protections: reverse‑polarity prevention, over‑charge, short‑circuit, over‑temperature, lightning surge protection
3.3 30kW Three‑Phase Power‑Frequency Off‑Grid Inverter
Power‑frequency isolation design enables strong inrush‑load capacity for water pumps and industrial machinery. Output complies with Philippine 60Hz requirement.
Rated output power: 30kW
DC input voltage: 192V
AC output: 3‑phase 380V/220V, 60Hz
Output waveform: pure sine wave; THD < 3%
Overall efficiency: ≥88%
Overload capability: 150% overload for 10 seconds to handle inductive‑load startup surges
Built‑in protections: low‑voltage, over‑voltage, overload, short‑circuit, over‑temperature
Expansion: reserved diesel‑generator interface for future backup‑power integration
3.4 16kWh Outdoor Energy‑Storage Lithium‑Iron‑Phosphate Cabinet (4 units parallel)
Capacity per cabinet: 16kWh; total system capacity: 64kWh
System DC rated voltage: 192V
Cell grade: new EVE Grade‑A lithium‑iron‑phosphate cells
Management: integrated BMS with cell balancing and real‑time status monitoring
Cycle life: ≥8000 cycles @ 80% depth‑of‑discharge
Cabinet protection class: IP54 outdoor‑rated
Environmental tolerance: high‑temperature resistant, humidity‑proof, salt‑spray resistant, dust‑proof
Protections: over‑charge, over‑discharge, over‑current, short‑circuit, high‑/low‑temperature multi‑level safety protection
4. System Working Principle & Electrical Topology
This is a fully standalone off‑grid system without utility‑grid connection. Energy‑flow logic is described below:
60 pieces of 590W PV modules form the solar array to convert solar irradiance into DC power.
PV power is fed into two 192V 100A MPPT controllers working in parallel for regulated high‑efficiency charging.
Controllers adjust charging strategy according to battery SOC and charge the 192V / 64kWh lithium‑iron‑phosphate energy‑storage bank.
Stored DC power is fed to the 30kW three‑phase off‑grid inverter and converted into 3‑phase 380V / 60Hz AC power matching Philippine local standard.
AC power supplies island production machinery, equipment and residential loads on a 24‑hour basis.
The whole system operates in closed‑loop standalone mode with zero dependency on public grid.
5. Power Generation & Power‑Supply Capacity Calculation
PV installed capacity: 35.4kWp
Average daily effective sunshine hours on target island: 5 h
Theoretical daily energy yield: approx. 177 kWh
Total energy‑storage capacity: 64 kWh; practical available energy (80% safe DOD): approx. 51 kWh
The system delivers stable three‑phase high‑power output. Daytime PV generation covers real‑time loads while surplus power is stored. At night or during overcast‑rainy weather, energy storage sustains continuous power supply, achieving round‑the‑clock power guarantee for off‑grid island sites.
6. Specialized Island Construction Standards
Considering high‑temperature, high‑humidity, heavy salt‑spray and frequent‑typhoon island conditions, project construction follows enhanced specifications:
Salt‑spray & anti‑corrosion treatment: PV mounting structures adopt hot‑dip galvanizing; all fasteners are stainless‑steel grade. Cables are UV‑resistant and seawater‑corrosion resistant to mitigate salt‑atmosphere degradation.
Typhoon‑resistant reinforcement: Concrete‑hardened foundations for PV racks with optimized tilt angle to improve wind‑load resistance.
Full‑range lightning‑protection & earthing: System‑wide standardized earthing plus AC‑DC two‑stage surge‑protection devices to mitigate lightning risks.
Waterproof & dust‑proof measures: All cable joints are sealed; core electrical devices are housed in dedicated rain‑proof ventilated rooms to avoid condensation‑induced failures.
Standardized cabling: Strict separation of power and signal cables with neat routing and reserved maintenance space, suitable for long‑term overseas unattended operation.
7. Core Project Advantages
Full‑set self‑developed devices with high internal compatibility and reliable coordinated operation.
Well‑balanced PV‑to‑storage sizing: 35.4 kW PV paired with 64 kWh storage realizes reliable day‑and‑night power balance.
30 kW three‑phase power‑frequency output offers strong inrush‑load capability for heavy‑duty loads such as water pumps and industrial units.
Industrial‑grade island‑oriented hardware, custom‑built for high‑temperature, humid, salt‑spray‑rich and typhoon‑prone environments.
Modular architecture supports flexible future expansion of PV arrays and battery banks according to growing load demand.
Intelligent EMS energy‑management system enables fully automatic unattended operation with remote data monitoring and fault alert functions.
Replaces costly and polluting diesel generation, cuts long‑term OPEX and achieves zero‑emission clean power supply.
8. Operation & Maintenance Recommendations
Quarterly cleaning: Remove sea‑salt deposits and dust from PV modules to preserve transmittance and avoid hot‑spot risks.
Periodic inspection: Check mounting‑bolt tightness, cable waterproofing and joint ageing status to eliminate loosening or corrosion hazards.
Pre‑storm maintenance: Carry out comprehensive system inspection and structural reinforcement before typhoon or rainy seasons for equipment safety under extreme weather.