Rooftop Workflow

Overview

Rooftop systems typically use landscape orientation (panels wider than tall) to maximize coverage on pitched roofs. Branch automatically detects this orientation and optimizes string routing accordingly.

Step 1: Prepare Your Drawing

Start with your panel layout already drawn in AutoCAD. Panels can be:

• Closed polylines representing panel outlines
• Blocks with consistent naming (e.g., "PV_Module")
• Rectangles at actual panel dimensions

Step 2: Create Panel Groups

Panel groups organize your panels into logical arrays that can be strung together.

Select panels in your drawing, then run this command. It breaks up the selected panels into sub-array groups based on proximity and alignment:

1. Analyzes positions and orientations of selected panels
2. Groups panels by proximity and alignment
3. Creates a bounding polyline around each group (on the "Panel Group" layer)

After running, you'll see colored outlines around each panel group, along with header labels showing how many panels to add or subtract to achieve perfectly even string lengths.

Step 3: Adjust Panels for Even Strings

Each panel group header displays a recommendation (e.g., "+2" or "-1") indicating how many panels to add or remove to get perfectly even string lengths based on your configured string size.

To balance your strings:

1. Review the header recommendations on each panel group
2. Run ADDPANELS
3. Choose Auto to fill all incomplete groups in the drawing at once, or select a specific target group manually
4. If manual, select panels from other panel groups or unassociated panels to transfer
5. The transferred panels will visually join the target group

This step ensures all strings have the same number of panels, which simplifies inverter configuration and maximizes system efficiency.

Step 4: Solve Strings

The solver automatically generates optimized string connections within each panel group.

The solver optimizes for:

• Fastest install time — Minimizes jumps between rows and keeps them at row ends
• Reduced UV-rated wire — Optimizes routing to minimize exposed cable runs

For rooftop systems, strings typically run horizontally along rows, then connect vertically between rows. The solver creates polylines on the "String" layer.

Step 4b: Edit Strings (Optional)

If the automatic solution doesn't work for certain areas, you can delete individual strings and redraw them manually or with the most recent string length.

To edit strings:

1. Run DELETESTRING and select the string(s) you want to remove
2. Add strings back using one of these options:
   • SINGLESTRING — Adds all selected panels to a single string, regardless of the configured string length
   • MULTISTRING — Draws strings over all selected panels using the configured string length. If the panel count doesn't divide evenly, the program may use smaller string lengths for remaining panels
3. The redrawn string will integrate with the existing solution

Step 5: Place Inverter

Add your inverter to the drawing so homeruns can be routed to it.

This command offers three modes:

• Automatic — Assigns the nearest unassigned strings based on the number of DC connections specified in settings
• Manual — You select which strings to assign, up to the DC connections limit
• Add Later — Places the inverter block without assigning any strings. Use ASSIGNSTRINGS afterward to batch-assign across all inverters at once

Once strings become associated with an inverter, their color and tagging will update to reflect the assignment. For multiple inverters, use ADDALLINVERTERS to automatically place inverters for all unassigned strings.

Step 5b: Assign Strings (if using Add Later)

If you placed inverters with Add Later mode, assign strings to them now.

Choose a mode:

• Auto — Optimizes assignments across all inverters based on proximity. Minimizes total wiring distance
• Manual — Select an inverter, then pick which strings connect to it. Repeat for each inverter

After assignment, string tags and colors update to show their inverter association.

Step 6: Balance inverters

After placing inverters, check that strings are evenly distributed across MPPT inputs.

The Inverter Manager shows balance status for every inverter in your drawing. Inverters with mismatched string panel counts are flagged and sorted to the top. When a module and inverter are configured in BRANCHOPTIONS, each inverter row shows its DC/AC ratio, and each MPPT column displays its DC power in kW.

What to look for

• Green rows — All MPPTs balanced, no action needed
• Yellow/Red rows — Panel count mismatch on one or more MPPTs. Review the suggested swaps or click Auto-Balance All

Double-click any suggested swap to apply it, or click Auto-Balance All to fix all inverters at once. Every swap is tracked in the history panel — you can undo individual swaps or revert to any previous state.

Step 7: Create homeruns

Route cables from string endpoints to the inverter or combiner box.

This command generates schematic homerun routing:

1. Identifies string endpoints
2. Creates schematic routing to the inverter (not optimized pathing)
3. Creates homerun polylines on the "HomeRun" layer

Step 7b: Adjust Homeruns (Optional)

Fine-tune homerun routing to match your actual site conditions.

Four editing operations:

• Move Segment — Slide a trunk segment perpendicular to its direction
• Angle Vertex — Drag a vertex freely to create angled routing
• Insert Vertex — Add a waypoint along a segment for more control
• Delete Vertex — Remove a waypoint to simplify routing

Step 8: Set Elevation Zones (Optional)

For rooftop systems with varying roof elevations, define zones to account for height differences in your circuit length calculations.

The Zone Height Manager lets you:

1. Create named elevation zones with a height offset in drawing units
2. Assign strings to zones by selecting them in the drawing
3. Visualize zone boundaries — colored bounding boxes and labels appear around assigned strings while the form is open

When zones are defined, CABLEEXPORT adds three columns: Zone, Elev. Offset*, and Adj. Circuit Length*. The offset is applied independently to each +/− homerun.

Step 9: Review & Export

Review your design and export data as needed.

Troubleshooting

Frequently Asked Questions