How to read a solar single-line diagram: symbols and energy path

September 29, 2026 · 6 min read · Danilo Nascimento

Learn to read a solar single-line diagram: what each block means, how to follow the energy from the panels to the grid and what to check in each section.

What a single-line diagram is

The single-line diagram shows, with a single line per circuit, how the equipment is connected: what feeds what and through which protections the energy passes. It does not show the physical position of the equipment, but the system’s electrical logic.

Single-line diagram

The logic of the installation

One line for each circuit
Shows sources, loads and protections
Serves for design and for talking with the installer

Physical layout

Where everything is

Shows the roof, the cables and the equipment
Indicates distances and routes
Complements the single-line, but does not replace it

The two drawings complete each other: the single-line says how, the layout says where.

Symbols and blocks

In the Editor Solar each block is a piece of equipment, connected by wires of different types (DC positive, DC negative, AC and earth). Tap the devices below to see what each does and where to look for information about it.

Interactive

What does each block mean?

Tap a block to read what it does in the system and what to check on it when reading a diagram.

DC side (direct current)AC side (alternating current)Earthing

AC output

The earth appears separately, connected to the metal parts, the inverter and the SPDs. It is a protection circuit, not an energy one.

Panels (DC source)

The origin of the energy. Check the total power and how they are connected in series and parallel (strings).

Where it goes: on the left, at the start of the drawing

DC isolator

The disconnection point of the panels. Check whether it exists and where it is.

Where it goes: between the panels and the inverter

Inverter

DC → AC

Converts DC to AC. In a hybrid, it also connects the battery. Check the power, the input voltage and the number of MPPTs.

Where it goes: in the centre, between the DC side and the AC side

AC breaker

Protects the inverter’s output cable and lets you switch it off. Check the rated current.

Where it goes: at the inverter output

Distribution board

Gathers the home’s circuits and receives energy from the inverter and the grid.

Where it goes: after the breaker, before the grid and the loads

Earth

protection

Shows the protective connections. Check that the structure, the inverter and the SPDs are connected to the busbar.

Where it goes: at the bottom of the drawing

How to read: follow the energy

1
1. Start at the source
Find the panels: the total power (kWp) and how many strings there are.
2
2. Follow the DC side
See the isolator, fuses and SPD up to the inverter. Check the strings’ maximum voltage.
3
3. Pass through the inverter
Note the power and type (string, hybrid or off-grid) and whether the battery connects to it on the DC side.
4
4. Follow the AC side
Breaker, board, meter and grid. Notice where the protections are and the connection point.
5
5. Look for the battery and the backup
See whether there is an essential circuit, and how the generator comes in, if there is one.
6
6. End at the earth
Check the earth connections of the structure, inverter, board and SPDs.

Types of connection

DC positive and DC negative

DC side

The two direct-current conductors between panels, batteries and inverter. Each pole has its function, and polarity matters.

AC

AC side

The alternating current that leaves the inverter and feeds the board, the home and the grid.

Earth

protection

Protection and equipotential bonding circuit. It does not carry the system’s normal energy.

What to check before accepting a drawing

All blocks are named, with power or voltage indicated
There is a continuous path from the source to the load, with no loose blocks
Protections appear in the DC and AC sections, and the disconnection is clear
The earth is drawn and connected to the metal parts and the SPDs
Battery, generator and backup, if any, show what feeds what

Draw it in Editor Solar

This is Editor Solar itself, already loaded with the diagram from this article. Move the equipment, edit labels, connect new parts and export to PNG, SVG or PDF. It is free and runs right in your browser.

A 5.5 kWp hybrid system drawn as a single-line diagram: the energy runs from left to right, with the battery as a branch and the earth drawn separately.

Try it: Pick one of the Editor Solar’s ready-made templates and write, next to each block, what it does and in which section (DC, AC or earthing) it sits.

Ready-made templates: see all diagram templates

Open this diagram in the full editor ↗

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