Electrical Parameters
Configure string sizing, inverter inputs, and understand how Branch tracks electrical data for your solar designs.
String Configuration
The string length is the number of panels connected in series to form one string. This is typically determined by your inverter's voltage window and the panel Voc.
| Parameter | Where to Set | Description |
|---|---|---|
| String Length | BRANCHOPTIONS | Number of panels per string (e.g., 12, 14, 16) |
Calculate string length properly
String length should be calculated based on your inverter's MPPT voltage window and the panel's Voc at the lowest expected temperature. This calculation is outside Branch's scope—use your preferred sizing tool or manufacturer guidelines.
Inverter Configuration
Configure how strings are distributed across your inverter's MPPT inputs.
| Parameter | Example Values | Description |
|---|---|---|
| Number of MPPTs | 2, 3, 4 | MPPT inputs on your inverter model |
| Strings per MPPT | 2, 3 | How many strings can connect to each MPPT |
| Total Strings per Inverter | (calculated) | MPPTs × Strings per MPPT |
Example Configuration
For a SolarEdge SE7600H with 3 MPPT inputs and 2 strings per MPPT:
- • Number of MPPTs: 3
- • Strings per MPPT: 2
- • Total strings per inverter: 6
Circuit Designation Format
When strings are assigned to inverters, Branch creates a circuit designation that identifies each string's location in the electrical system.
1/4a1Inverter Number
4String Number
aMPPT Input
This format makes it easy to:
- • Trace cables during installation — Know exactly where each string connects
- • Troubleshoot issues — Quickly identify which MPPT a problem string is on
- • Document the system — Clear labeling for construction documents and O&M
MPPT Letters
MPPTs are designated with lowercase letters starting from 'a':
a = MPPT 1b = MPPT 2c = MPPT 3d = MPPT 4Cable Data Export
Branch tracks cable lengths for BOM generation and downstream engineering analysis.
CABLEEXPORTOpens the cable export dialog showing all string and homerun cable data.
Data Available
| Field | Description |
|---|---|
| Circuit | Circuit designation (e.g., "1/4a") |
| Type | String, Start Homerun, or End Homerun |
| Length | Cable length in drawing units |
| Inverter | Assigned inverter number |
| Panel Count | Number of panels in the string |
Export Features
- • Click to zoom — Double-click any row to zoom to that cable in the drawing
- • CSV export — Export data for spreadsheet analysis or BOM generation
- • Filter options — Filter by inverter, cable type, or other criteria
Best Practices
Match string length to inverter specs
Calculate string length based on your inverter's MPPT voltage window. Too few panels may not reach minimum voltage; too many may exceed maximum voltage.
Balance panels across groups
Use ADDPANELS to ensure each panel group has a panel count divisible by your string length. This avoids uneven strings and wasted panels.
Match panel counts per MPPT
Use INVBALANCE to open the Inverter Manager. It analyzes every inverter, suggests swaps to match panel counts on each MPPT, and can auto-balance your entire drawing with one click.
Verify cable data before export
Use CABLEEXPORT to review cable lengths and check for any outliers that might indicate routing errors before generating your BOM.