A single-line diagram (SLD) is a simplified electrical drawing that represents a solar PV system on one line, showing the panels, inverter, isolators, metering and grid connection without drawing every individual conductor. In Australian solar it is required documentation: you need one for STC paperwork and for grid-connection applications to your DNSP or retailer.
What is a single-line diagram in solar PV?
It is the one-line map of how a PV system is wired, from array to grid. Instead of showing all three phases or every cable, an SLD uses a single line and standard symbols to show the path of energy and the protection along the way: PV array, strings and MPPTs, inverter, DC and AC isolators, switchboard, metering, and the connection to the grid. It is the drawing an electrician, inspector or network reads to understand the installation at a glance.
What does a solar SLD show?
A typical residential SLD shows the elements in sequence from the array to the grid:
- PV array, with module type, quantity and how strings are grouped.
- Strings and MPPTs, showing how the array connects to each inverter input.
- Inverter, with model and rating.
- DC and AC isolators and any protection devices.
- Main switchboard, metering and the point of grid connection.
- Battery and hybrid components, where the system includes storage.
Why is an SLD required in Australia?
Because it is the document that proves the system is designed safely and to standard. An SLD is part of the evidence for claiming STCs and is requested in grid-connection applications, and it should reflect AS/NZS 5033 and the wiring rules. Without a clear, compliant SLD, a job can stall at approval. For the detail on what the standard expects, see our guide to AS/NZS 5033 SLD requirements.
How do you create a single-line diagram?
You can draw an SLD by hand, in generic CAD like AutoCAD or Visio, or in purpose-built solar SLD software. The fastest route is software that already knows your system: Solar Proof's SLD editor auto-populates from your design, so the panels, inverter and strings are already placed, and you confirm the layout and export a print-ready PDF. If you would rather follow the manual steps once to understand the parts, we have a walkthrough on how to draw a solar SLD.
SLD vs wiring diagram: what is the difference?
A single-line diagram is a high-level overview on one line; a wiring diagram (or schematic) shows the actual conductors, terminals and connections in full. The SLD answers "how is this system structured and protected?" while a wiring diagram answers "exactly which wire goes where?". For solar compliance and grid applications, the SLD is the document usually required.
The bottom line
A single-line diagram is the one-line electrical drawing that documents how a solar PV system is wired and protected, and in Australia it is required for STC and grid-connection paperwork. Drawing it in solar-specific software, rather than from a blank CAD canvas, is the quickest way to produce one that reflects AS/NZS 5033. See how Solar Proof draws SLDs in the browser →
