The following steps apply to small-scale distributed systems on rooftops or ground, and can also serve as a “scaled-down” reference for industrial and commercial power plants. It is crucial to focus on five key aspects: design, support structure, components, electrical systems, and commissioning. Errors in any of these steps can reduce power generation or even cause safety accidents.
1. Preliminary Survey and System Design
(1) On-site Light Measurement: Use a compass/drone to determine due south orientation and measure the length of shadows cast by obstructions to ensure no obstructions between 9:00 and 15:00.
(2) Load Calculation: Concrete roofs must have a load capacity of ≥2 kN m⁻², and corrugated steel roofs ≥0.2 kN m⁻² before direct installation; otherwise, reinforce with steel clamps or independent foundations.
(3) Capacity Matching: Convert the electricity bills for the past 12 months into daily average kWh, then calculate the module Wp based on the local annual peak sunshine hours × system efficiency of 0.75–0.8; calculate the battery capacity based on “self-sufficiency days × daily average power ÷ depth of discharge”.
(4) Produce a single-line diagram and bracket layout CAD, confirming that the string length (generally 8–14 540 W modules/string) matches the inverter MPPT range.
2. Bracket Installation
(1) Ground System: C-shaped steel columns and ground piles must be aligned horizontally in rows and vertically in columns. The top elevation deviation of columns in the same array should be ≤5 mm. 2–3 bolts should be exposed and coated with anti-rust grease.
(2) Roof System: Color steel tiles should be edged with a special “double-clamp” system, with one clamp per wave peak. Concrete roofs should use M10 chemical anchors, with a pull-out test result ≥1.5 kN/point. The brackets and roof should be double-protected with waterproof rubber pads and anti-loosening gaskets.
(3) Inclination Angle and Spacing: 10–12° for latitude 5–10° North; 20° for latitude 20° North; front and rear row spacing ≥1.2×H (H is the vertical height difference between the highest point of the front row and the foundation surface of the rear row), ensuring no shadows between 9:00 and 15:00 on the winter solstice.
3. Component Installation and Wiring
(1) Handling: Double-glass components must be lifted horizontally by two people; do not grab the frame with one hand. For lightweight components, use structural adhesive + double-sided adhesive for spot bonding in environments of 5–30 ℃; preheat the adhesive tube before use if the temperature is below 5 ℃.
(2) Fixing: The central pressure block should be centered, and the side pressure blocks should be 20 mm from the frame. Bolt torque should be 12–15 N/m. For components with a long side ≤ 2 m, fix at least 4 points.
(3) Wiring: Insert MC4 first, then pull the latch. A “click” sound will be heard when it is fully inserted. Use red/black heat shrink tubing to distinguish the polarity of the same string. The bending radius of the cable should be ≥ 50 mm.
(4) Lightning Protection: The bracket should be electrically connected to the roof lightning protection strip. A Class II SPD should be installed within ≤ 30 m on the DC side, with a grounding resistance ≤ 4 Ω.
4. Inverter and Electrical Configuration
(1) Site Selection: For residential installations, prioritize mounting on the north wall or in a well-ventilated indoor location, ≥1.5 m above the ground, away from flammable materials such as gas and oil tanks; ambient temperature ≤45℃, humidity ≤95%.
(2) Wiring: On the DC side, disconnect MC4 first, then turn off the DC circuit breaker; on the AC side, follow the sequence: “Inverter → AC circuit breaker → grid-connected metering box → power grid,” confirming the phase sequence with a phase meter.
(3) Grounding: The inverter’s PE terminal and bracket are grounded together using a 16 mm² yellow-green wire; the measured grounding resistance is <4 Ω; apply conductive paste to the grounding grid connection points.
(4) Communication: RS485/PLC lines are run in separate conduits, parallel to power lines with a distance ≥100 mm to avoid interference with backend monitoring.
5. System Commissioning and Grid Connection
(1) Insulation Test: Use a 1 kV megohmmeter to measure the insulation resistance to ground of positive and negative terminals. ≥40 MΩ (system voltage ≤1 kV).
(2) Open Circuit Voltage: The open-circuit voltage of each string should deviate from the theoretical value by ≤5%. If too high, check the number of series connections; if too low, check for loose connections.
(3) Before Grid Connection: Connect DC → wait for self-test → green light stays on → then connect AC; observe the inverter display power factor ≈1, voltage harmonics THD <3%.
(4) Data Verification: The error between the real-time power displayed on the mobile app and the clamp meter on site should be ≤2%; continuous operation for 24 hours without alarms is considered successful commissioning.
6. Maintenance Access and Data Transfer
(1) Leave a ≥0.6 m inspection passage for each row of components. Install aluminum alloy steps or glass grid ladders at the ends of the pitched roof to avoid repeated stepping on the tile surface, which could lead to water leakage. (2) Infrared thermal imagers shall be inspected every six months. If a localized temperature rise exceeding 20°C is found, the diodes or junction boxes shall be replaced immediately.
(3) As-built documentation: This includes system design drawings, support frame mechanical calculations, electrical single-line diagrams, grounding test records, component/inverter warranty certificates, and SPD certificates of conformity, all of which shall be handed over to the owner.