Project Background and Requirements

As a pilot county for distributed PV projects in Zhejiang Province, Tiantai County is characterized by mountainous terrain, complex rooftops, and widespread partial shading. The project owner is a local manufacturing enterprise, with a factory rooftop area of approximately 7,000㎡. The rooftop features a multi-slope, staggered-height structure, presenting challenges such as shading, uneven load-bearing capacity, and strong electromagnetic interference (from frequency converters/motors). The core requirements focus on four key areas:

• Maximize rooftop space utilization, increase power generation, and achieve maximum returns;
• Eliminate DC high-voltage risks, ensure factory production safety, and comply with fire safety regulations;
• Ensure anti-interference, low bit error rate, and stable communication, suitable for the factory's high-interference environment;
• Enable module-level monitoring and simple maintenance, reduce long-term management costs, and align with Zhejiang's low-voltage multi-point connection policy.

Conventional string inverter solutions fail to meet the requirements due to issues such as DC high voltage, shading mismatch, and unstable communication. Therefore, a full microinverter solution was ultimately selected to thoroughly address these industry pain points.

Core System Configuration (658.88 kWp)

Photovoltaic Modules

Specifications: 580Wp high-efficiency monocrystalline silicon modules

Quantity: 1136 pieces (1136 × 580W ≈ 658.88 kWp)

Characteristics: High power, low degradation, anti-PID, suitable for high-temperature, high-humidity coastal environments

Microinverter (Core)

Model: Single-phase microinverter (1-to-4)
Individual power: 2kW

Mounting and Installation

Type: Aluminum alloy rail + waterproof clamp (suitable for both color steel roofs and concrete roofs)

Tilt angle: 22°~28° (optimal tilt angle for Tiantai)

Features: Non-penetrating roof, reliable waterproofing, lightweight, suitable for load-bearing capacity of old roofs

Grid Connection and Monitoring

Grid connection: 0.4kV low-voltage multi-point connection (simplified grid connection process in Zhejiang)
Monitoring: Cloud platform + local touch screen, module-level real-time data monitoring
Protection: Full protection including over/under voltage, islanding, leakage, lightning protection, and high-temperature derating

Key Technical Solution (Microinverter Advantages in Practice)

Module-level MPPT: 12%~18% increase in power generation

Each module has an independent MPPT, so shading, dirt, and orientation differences do not affect other modules. Compared with string inverters, this increases annual power generation by approximately 120,000 kWh.

Ultimate Safety: Low-Voltage DC with No Hazards

The DC side voltage of each module is < 120V (safe voltage for the human body). There is no DC high-voltage cable, no risk of arcing, and it is fully compliant with fire safety regulations. Live maintenance in the factory is safe and risk-free.

Superior Anti-Interference: Zero Communication Failures

The microinverter uses AC side communication / carrier communication, which is isolated from RS485 DC interference. In the factory's high-interference environment, the bit error rate is < 10⁻⁸, with no packet loss, no CRC errors, and no disconnections.

Rapid Construction and Phased Deployment

Microinverters can be installed and connected to the grid immediately. Construction can be carried out in zones without affecting the factory's normal production. The construction period is shortened by 30%, and labor costs are significantly reduced.

Power Generation and Revenue Estimation (Tiantai Area)

Annual power generation

First-year power generation: approximately 798,000 kWh (equivalent utilization hours ≈ 1211h)

Total power generation over 25 years: approximately 18.35 million kWh, with an average annual degradation of <0.45%

Economic Benefits

Self-consumption ratio: 75% (aligned with daytime peak production hours)
Revenue per kWh: Self-consumption ≈ RMB 0.85/kWh; Surplus electricity fed into the grid ≈ RMB 0.41/kWh
Total annual revenue: ≈ RMB 625,000
Simple payback period: ≈ 5.8 years

Environmental Benefits

Annual CO₂ reduction: ≈ 795 tons
Total carbon reduction over 25 years: ≈ 18,300 tons

Equivalent to planting: ≈ 430,000 trees, contributing to the achievement of carbon peak and carbon neutrality goals.

Project Value and Industry Significance

Safety Benchmark: The first 600kW+ all-microinverter commercial and industrial PV plant in Tiantai, Zhejiang, featuring zero DC high voltage, and having passed high-standard inspections by the fire protection and safety supervision authorities.
Generation Benchmark: Under complex shaded rooftop conditions, it generates 12%~18% more electricity than string inverter solutions, validating the absolute advantage of microinverters in mountainous, multi-slope, and heavily shaded scenarios.
Reliability Benchmark: In a high-interference industrial environment, the communication bit error rate is <10⁻⁸, solving the industry pain points of "unstable communication and data loss" in industrial PV systems.
Policy Alignment: Compliant with Zhejiang's county-wide PV promotion, low-voltage grid connection, and unrestricted self-consumption ratio policies, providing a replicable model for large-scale adoption of commercial and industrial microinverters in Tiantai and eastern Zhejiang.