Bill of materials

The bill of materials — the BOM — is a materials list computed from the layout you have generated. It opens as a table beside the plot, every cell in it is editable, and the finished list prints as its own pages in the exported PDF report.

It is not a separate document you keep by hand. The quantities are read out of the plant, so a layout that changes and is generated again produces a different list. What you add on top of that — extra line items, corrected descriptions, remarks for a procurement team — is yours, and it stays until you ask for the list to be rebuilt.

Opening the list

📋 BOM on the plot toolbar switches the mode on. It is off by default. Generate a layout first: the list is computed from a placed plant, and there is nothing to compute before one exists.

The list is part of the session, so it is saved into the project file along with the inputs, the layout and your sketch edits, and comes back when the project is reopened. See Projects.

The five columns

The table has a fixed set of columns, in this order.

Quantity and Unit are deliberately separate. A line counted in numbers and a line counted in metres sit in the same table without ambiguity, which matters as soon as cables and structures appear on the same list.

The controls

Three buttons sit above the table, and they do exactly what their labels say.

What rebuilding does

⚙ Rebuild from Layout is not a refresh that merges. It recomputes the whole list from the current plant and puts that in place of what was there.

That is the behaviour you want in one specific situation and not in any other:

• Rebuild after you have changed the layout — moved a control room, drawn an obstruction, added or deleted tables by hand, turned cable calculation on, run the cleaning tool — and you want the quantities to match the plant again.
• Do not rebuild once you have started editing the list for real. Finish the layout first, rebuild once, then edit. The order costs nothing and saves the work.

If you need both — a fully edited list and a set of current quantities to check it against — export the edited list to a spreadsheet before rebuilding, then compare the two outside the application.

Editing a cell

Click any cell and type. Every column is editable, including the computed quantities — so a figure you overwrite is a figure you own from then on, and it stands until the list is rebuilt.

Three edits are worth making even on a list you otherwise leave alone:

• Descriptions. The computed text is generic. Replacing it with the designation your organisation buys against turns the list into something a supplier can quote from.
• Remarks. Cable specifications, connector types, structure grades and finishes — the detail the layout has no way of knowing.
• Missing line items. Anything the plant's geometry cannot imply. Read the computed list against your own material take-off and add what is not in it.

For a starting point that already has that detail written in, load one of the built-in templates rather than typing it from scratch. See Materials list templates.

Where the quantities come from

Two sources, and understanding the split tells you which figures move when you change the design.

The plant's own counts. Everything the layout has placed and measured is already known — the module count, the full and half tables or tracker units, the inverter control rooms, the string inverters or string monitoring boxes, the lightning arresters, the street lights, the piles, and the cable and trench lengths. These are the same figures the summary table reports under the plot, so the two never disagree. See Summary columns.

The topology rules. Some quantities are not placed on the ground and have to be derived from a rule instead. The switchgear and transformer counts are the clear case, and they follow three rules:

The IDT is the three-winding transformer in the diagram symbol set. The reason these three numbers matter here rather than only in the electrical design is that the single-line diagram's automatic build uses the same rules. Build the diagram from the plant and it groups inverters into ACCBs, ACCBs into transformers and transformers onto the medium-voltage panel by exactly the counts above — so the diagram and the materials list agree on how many of each there are. See Automatic diagram build.

What the list contains

The rows come out in a fixed order. A row whose quantity would be zero is left out altogether, so a short list is not a fault — it means the plant has none of that item.

Four things change that list:

• A tracker plant replaces the two table rows with Tracker (Full) and Half Tracker.
• A central-inverter plant replaces String Inverter with SMB (String Monitoring Box) and Central Inverter, adds DC Cable (SMB → Central Inverter), and renames the second trench row to match — there is no AC leg. See Choosing a design mode.
• Running without cable calculation drops every cable and trench row.
• Not placing a main control room drops the five rows from the switchgear panel down to the room itself.

The cleaning robot fleet

The robot fleet is the one quantity that appears only because you asked for it. Run 🤖 Robotic Module Cleaning, decide which wide gaps you will bridge, and the resulting fleet size feeds both the summary's Robots column and this list. Until you run it, there is no fleet on the list at all.

That is deliberate. A cleaning fleet is a purchase decision with a bridge count attached to it, not something a layout implies, so the list never carries a fleet you did not ask for. See Robotic module cleaning.

Exporting the list

Two exports, both of the list on screen rather than the computed one — whatever you have edited is what is written.

⬇ Export BOM to PDF is separate from the report. The PDF report already carries the materials list as its own Bill of Material pages, paginated across as many pages as the list needs, alongside the drawing, the summary and the diagram. Use this button when you want the list on its own — a purchasing department rarely wants the engineering drawing attached to it. See The PDF report.

Enlarging the working area

Hide Layout & Energy Summary collapses the plot and the summary table so the materials list has the width of the window to itself. On a long list this is the difference between reading a row and scrolling to read a row.

The layout is unaffected — nothing is discarded, and switching the option off brings the plot and the summary straight back.

What the list is, and is not

State this to whoever receives it, because it sets what they can do with it.

• It is a materials list, not a priced bill of quantities. There is no rate column, no amount column and no total. Pricing happens after the export, in the spreadsheet.
• The descriptions are generic. They describe the item, not a supplier's catalogue part. Nothing here is tied to a make, a model or a stock code until you type one in.
• It follows from a layout, so it inherits the layout's assumptions. Cable quantities exist only if cable calculation was on for the run; a fleet exists only if you sized one; arresters exist only if you asked for them. A zero on this list is usually a setting rather than an absence.
• Nothing is checked against a standard. Quantities are counts and lengths, not a verified schedule of material.

A working order

The list is cheapest to produce if the plant is finished before you start editing it.

Where to go next