5MW Solar Roof Mounting Project Construction Organization Design

Project Overview and Characteristics

1. Basic Project Information

• Installed Capacity: 5MW (divided into three grid connection points of 2MW, 2MW, and 1MW)
• Installation Location: Industrial park rooftops (approximately 80% metal roofing and 20% concrete roofing), with a usable area of about 52,000 m²
• Module Type: 550W monocrystalline bifacial modules (9,100 units), with a tilt angle of 10°–15°
• Inverter Configuration: String inverters (50kW × 90 units)

2. Key Challenges

• Decentralized rooftops and complex ownership: Requires coordination among five different property owners.
• Reinforcement and waterproofing of metal roofing
• Grid connection: Must align with the power utility’s approval process for connection points.

Overall Deployment and Objectives

1. Organizational Structure

• Project Management Office: Includes one project manager, one technical lead, and one safety supervisor.
• Construction Teams: Divided into three working groups (module installation team, electrical construction team, and commissioning support team).

2. Key Milestone Targets

3. Construction Master Plan Layout

• Materials Storage Area: Includes a temporary shelter for modules (protected from rain and dust) and a cable reel storage zone.
• Fabrication Area: Dedicated space for bracket cutting and welding (with dust removal equipment).
• Temporary Power Supply: Three 250kVA box-type transformers connected to the owner’s low-voltage distribution cabinet.

Construction Plan by Sub-Project

1. Rooftop Structural Treatment

• Metal Roof Reinforcement:
  • Utilize specialized roof clamps (model “CT-3”) to fix the support brackets, arranged at 1.5m intervals along each purlin span.
  • For areas showing signs of rust, apply an epoxy zinc-rich primer (thickness ≥ 80µm).
• Concrete Roof Waterproofing:
  • Embed chemical anchor bolts and then apply polyurethane waterproof coating (thickness 2mm, elongation ≥ 450%).

2. Support Brackets and Module Installation

• Bracket Installation:
  • Tolerance Control: Vertical deviation of columns ≤ 3mm/m; horizontal beam spacing deviation ±5mm.
  • Grounding for Lightning Protection: Use 40×4mm galvanized flat steel with continuous welding (ground resistance ≤ 4Ω).
• Module Installation:
  • Fixed using mechanical clamps, with horizontal/vertical spacing deviations ≤ 2mm.
  • Important: Avoid stepping on the metal roof’s raised wave crests (workers may only walk in the wave troughs).

3. Electrical System Construction

• DC Side Construction:
  • String Design: 22 modules per string (22 × 550W = 12.1kW), each inverter connects 9–10 strings.
  • Cable Selection: PV1-F 4mm² photovoltaic cable (UV-resistant, operating temperature from –40°C to 120°C).
• AC Side and Grid Connection:
  • Each inverter’s AC output is fitted with a surge protector (Iimp ≥ 15kA).
  • The grid connection cabinet includes anti-islanding protection and an online power quality monitoring device.

Resource Allocation Plan

1. Workforce Plan (Peak Period)

2. Machinery and Equipment List

3. Materials Delivery Plan

• First Batch (5 days after project start): Steel for brackets, chemical anchor bolts, and grounding flat steel.
• Second Batch (20 days after project start): Photovoltaic modules, inverters, and DC cables.
• Third Batch (50 days after project start): Grid connection cabinet and monitoring system equipment.

Quality and Safety Management

1. Quality Standards

• Mandatory National Codes:
  • Code for Construction of Photovoltaic Power Station (GB 50794-2012)
  • Code for Design of Lightning Protection of Buildings (GB 50057-2010)
• Key Performance Indicators:
  • String current dispersion ≤ 3% (sample-check 10% with I-V curve tester).
  • Maximum roof membrane deformation ≤ 5mm (observed 72 hours after completion).

2. Safety Management Measures

• Control of High-Risk Operations:
  • Work at Height: 100% use of double-hook safety harnesses (lifelines installed on rooftop).
  • Hoisting Operations: Demarcate a restricted area; signal operators must be certified.
• Emergency Preparedness:
  • Heatstroke Treatment: Provide Huoxiang Zhengqi liquid and sunshades on site (no outdoor work from 11:00–15:00 on high-temperature days).
  • Electrical Fire: Equip each work area with two 5kg dry powder fire extinguishers.

Progress Assurance Measures

1. Dynamic Adjustment Mechanism

• Daily Morning Meeting: Summarize previous day’s progress deviation and adjust priorities for the current day’s tasks.
• Weather Alerts: Obtain weather forecasts three days in advance; shift to indoor electrical wiring on rainy days.

2. Schedule Optimization Strategies

• Parallel Construction: Execute rooftop reinforcement and pre-assembly of brackets simultaneously (pre-assembly ratio up to 60%).
• Modular Transportation: Transport modules by string sets to reduce on-site sorting time.

Acceptance and Handover

1. Staged Acceptance

2. Warranty Services

• Module Warranty: 12-year product warranty; performance degradation ≤ 20% over 25 years.
• Intelligent O&M: Deploy a monitoring platform (automatic fault dispatch, 2-hour response time).

References:

• Construction Master Plan Layout
• Rooftop Load Calculation (including structural institute approval)
• Grid Connection Electrical Diagram

Note: This plan should be adjusted based on the actual rooftop survey results (e.g., metal roof thickness, purlin spacing). If necessary, commission a third party to conduct load-bearing reviews.