What Is Solar Drafting Automation?

Solar drafting automation is software that handles the repetitive CAD work in solar construction document production. Instead of manually drawing strings, routing homeruns, measuring cable lengths, and placing tags in AutoCAD, the engineer defines parameters and the software produces the drafting output.

This is a narrow definition, and it's narrow on purpose. Drafting automation is not the same as solar design software, engineering calculation tools, or proposal platforms. Understanding the distinction matters when evaluating tools.

What Drafting Automation Does

The specific tasks that fall under drafting automation:

• Panel stringing — Connecting panels into strings that comply with voltage window requirements. The engineer defines the inverter, module, and temperature parameters. The automation places the string lines.
• Homerun routing — Drawing the paths from string endpoints to combiners or inverters. Good automation optimizes these routes to minimize cable lengths and follow logical groupings.
• Circuit and cable length calculation — Measuring the actual drawn path lengths and exporting them. This replaces the tedious DIST command workflow in AutoCAD.
• Tag generation — Placing equipment labels, string identifiers, and circuit tags on the drawing.

These tasks share a common trait: they require no engineering judgment. The decisions have already been made. The engineer chose the inverter configuration, determined string sizing, and placed the panel layout. Drafting automation takes those decisions and produces the drawings.

What Drafting Automation Is Not

Not solar design software. Tools like Aurora Solar, Helioscope, and Solargraf help win projects with proposals, energy models, and customer-facing documents. They operate at a different stage of the project lifecycle than drafting automation.

Not engineering calculation tools. Wire sizing, voltage drop analysis, ampacity calculations, and NEC code compliance are engineering decisions. Drafting automation does not make these decisions — it produces the physical objects on the drawing that represent the results of those decisions.

Not permit package generation. Drafting automation produces stringing plans, homerun routes, and cable schedules. A complete permit package includes title blocks, one-line diagrams, structural details, code compliance documentation, and engineering stamps. Drafting automation handles one piece of that package.

Why the Distinction Matters

For engineers

Drafting automation that stays in the drafting lane earns trust. Engineers rejected plenty of tools that claimed to automate their workflow but actually tried to override their engineering judgment. If the software is placing strings and calculating voltage drop simultaneously, who is responsible when the voltage drop calculation is wrong?

When software automates drafting only, the engineer stays in control. The output is deterministic — same inputs, same output. The engineer reviews the drawings the same way they would review a junior drafter's work.

For decision-makers

Drafting automation that doesn't make engineering decisions can't make expensive engineering mistakes. This matters when the question on the table is "should we let software automate part of our construction document production?" The risk profile of a tool that draws lines is fundamentally different from a tool that makes design calculations.

The Manual Workflow It Replaces

Here is what solar drafting looks like without automation, on a typical 500 kW commercial rooftop project:

1. Stringing — The engineer opens the panel layout in AutoCAD, determines string assignments based on inverter specs and voltage windows, and draws polylines connecting panels into strings. Each string is drawn individually. A project might have 30-40 string groups.

2. Homerun routing — For each string group, the engineer draws the homerun path from the last panel to the combiner or inverter. Route selection considers cable tray locations, shortest paths, and avoiding obstructions.

3. Cable length measurement — The engineer uses AutoCAD's DIST command or polyline properties to measure each cable run, records the lengths in a spreadsheet, and cross-references against the wire schedule.

4. Tagging — The engineer places text labels for string identifiers, circuit numbers, and equipment tags.

This process takes hours per project. It's not difficult work. An experienced engineer can do it perfectly — they've just done it hundreds of times before and will do it hundreds of times again.

What Automation Changes

With drafting automation, the same workflow becomes:

1. Define panel groups and electrical parameters
2. Run the stringing solver
3. Run the homerun router
4. Export cable lengths
5. Review the output

The output is the same set of construction document objects — strings, homeruns, cable schedules, tags — but produced in minutes instead of hours. And because it's fast, design changes stop being painful. When a layout changes, delete and rerun.

That speed changes how engineers think about commitment. They stop resisting revision requests because rework costs nothing. They can run a quick pass for an early estimate without worrying about wasted effort if the design evolves.

Tools That Automate Solar Drafting

Several AutoCAD plugins now handle solar drafting automation:

• Leaf/Branch — Stringing, homerun routing (K-means optimized), cable length export, tagging, and SolarEdge Designer PDF import. $299/user/month with a 14-day free trial.
• PVComplete/Enact Solar — Broader feature set including SLD generation. Now part of Enact Solar after two acquisitions.
• Virto.CAD — AutoCAD and BricsCAD support for rooftop and ground mount.
• PV Rocket — Drafting automation plus integrated engineering calculations.
• PVcase Roof Mount — Enterprise-grade with utility-scale simulation capabilities.

For a detailed comparison, see our AutoCAD solar plugin comparison or comparison hub.

The Bottom Line

Solar drafting automation is narrow by design. It does the work that engineers shouldn't have to do by hand — the repetitive, time-consuming drafting that adds hours to every project but requires zero engineering judgment. Engineers bring the decisions. Automation produces the drawings.

---

If you're drawing strings by hand, try Branch for 14 days free. No credit card, no sales call.