Completing the design of a solar project does not complete the work. For the permit application, the field team and the customer, the design must be turned into technical drawing sheets. In most companies these drawings are prepared by hand in a separate CAD program after the design is finished. This takes time and creates a risk of inconsistency between the design and the drawings. This article covers the three drawing sheets most commonly prepared for solar projects and the benefits of generating them directly from the design.
Single-line diagram
A single-line diagram shows the electrical structure of the plant in simplified form along a single line. It defines the path energy takes from the panels to the grid connection point and the equipment along that path. A typical single-line diagram includes:
- String configuration: modules in series per string and number of strings
- Inverters and the allocation of strings to MPPT inputs
- DC-side protection and isolation devices
- AC-side protection devices, distribution board and meter
- Cable types and cross-sections
- Grid connection point
The single-line diagram is a direct reflection of stringing decisions. We explain stringing and MPPT in our stringing and MPPT article.
Earthing plan
The earthing (grounding) plan shows how the plant's metal structures and electrical equipment are connected to earth. Its purpose is to protect people and property and to protect equipment against overvoltages. The plan typically shows:
- Equipotential bonding of the mounting structure
- Routing of earthing conductors
- Location of earth electrodes or the earthing grid
- Earthing connections of inverters and distribution boards
Earth resistance is measured on site during installation; the plan is the roadmap for that work.
General plant layout plan
The general layout plan shows the physical arrangement of the plant on site. Particularly for ground-mounted plants, it is the main drawing referred to by the field team, the permitting process and the customer. It typically includes:
- Panel blocks, rows and row spacing
- Locations of inverters, distribution boards and other equipment
- Cable routes
- Site boundaries, dimensions and north direction
We explain how row spacing is determined in our ground-mount row spacing article.
Benefits of generating drawings automatically from the design
| Manual drawing | Automatic generation from the design |
|---|---|
| Design data is re-entered in a CAD program | Panel layout, string and inverter data are taken directly from the design |
| Drawings must be updated separately when the design changes | Drawing sheets are regenerated from the current design |
| Risk of inconsistent panel and string counts | Drawings rely on the same data as the design and the proposal |
| Drawings can only be edited in the program they were drawn in | DXF output opens and can be edited in CAD programs such as AutoCAD |
| Hours of drafting for every project | Engineers spend their time on review and improvement |
Automatic drawing sheets in PVAGE
In PVAGE, drawing sheets such as the single-line diagram, earthing plan and general plant layout plan are generated automatically from rooftop design and ground-mount (mounting structure) design and exported as PDF and DXF. The PDF can be added directly to the application file or sent to the customer; the DXF opens in CAD programs such as AutoCAD and can be adapted to your company's title block and drafting standards. Because the drawings rely on the same data as the panel layout, stringing and inverter selection in the design, they are consistent with the proposal and the bill of materials.
The process from site survey to design, and from design to proposal and drawings, thus runs on a single platform. See the mounting structure design page for ground-mount design, or the 3D roof design page for rooftop design.
Explore the feature: Solar Drawing Sheets: Single-Line Diagram and Earthing Plan