Prefabricated Panel House Roof Rewiring

For rewiring the roof of a prefabricated panel house, you can refer to the secondary rewiring method or the renovation approach combined with photovoltaic (PV) installation, as detailed below:

Secondary Rewiring Method

During the structural construction surveying phase, mark control points and lines on walls, columns, and slabs according to decoration engineering requirements as construction references. For floor construction, snap a 50 cm horizontal line on the surrounding walls and columns as the floor elevation control line. During wall construction, snap wall edge lines and 50 cm control lines on both sides, and control the surface layer construction based on the 50 cm control line during wall plastering. After the outdoor wall structure is completed, use a theodolite to project a vertical control line in the middle of the window, and then transfer the elevation using a steel tape measure based on the +50 cm line of the first-floor exterior wall and snap it on the wall. The vertical control line for indoor openings is snapped according to the axis relationship, and the horizontal control line is measured upwards from the +50 cm line. To avoid misalignment between floors, make full use of structural openings and use a plumb bob for vertical alignment. When transferring measurements, do not project and hoist layer by layer or climb along rods. Instead, run a through-line or run a through-line every 3-4 floors. After running the line, check the dimensions room by room according to the drawings and have them verified by a line inspector to ensure accuracy.

Renovation Approach Combined with PV Installation

If the roof bearing capacity of a prefabricated panel flat house is weak, directly installing PV systems poses a high risk, and renovation is required to enhance the bearing capacity:

• Option 1: Install additional load-bearing steel beams indoors
  Erect I-beams below the floor slab to distribute the PV load, without the need for extensive roof demolition. This option is suitable for homeowners who do not want to make significant changes to indoor decoration. After the renovation, keep construction records and, if necessary, invite professionals to review the load to confirm that it meets the PV installation requirements.
• Option 2: Roof reinforcement
  Lay a steel mesh and pour a fine aggregate concrete reinforcement layer to enhance the overall bearing capacity and simultaneously redo the roof waterproofing. This option provides stronger roof integrity and upgraded waterproofing but has a longer construction period and higher cost. After the reinforcement is completed and the curing meets the standards, assess whether the incoming wires can be compatible with the PV system. Old incoming aluminum wires or copper wires with a small diameter have insufficient load-bearing capacity and require upgrading the main wire specifications to avoid overheating caused by power generation backflow. Wiring renovation should be carried out by licensed electricians, and insulation tests should be conducted after completion. Additionally, reasonably plan the installation points for inverters and distribution boxes to shorten the length of DC cables and reduce power loss.