String Map Auto-Generation
String Map Auto-Generation is an automated solar design capability that instantly creates optimized stringing & electrical design layouts for PV modules—without relying on manual wiring sketches, spreadsheets, or hand-drawn electrical diagrams.
It uses system parameters such as module count, inverter specifications, MPPT limits, voltage windows, layout geometry, shading conditions, and electrical code constraints to automatically assign module strings that meet performance, safety, and compliance requirements.
For solar designers, EPCs, and installers, this feature removes one of the slowest and most error-prone steps in PV engineering. Teams can generate construction-ready string maps directly inside professional workflows like Solar Designing, Shadow Analysis, and Solar Proposals—dramatically reducing design time while improving accuracy.
Key Takeaways
- Automates the most error-prone part of PV electrical design
- Ensures voltage, current, MPPT, and shading compliance
- Reduces installation mistakes and engineering rework
- Produces construction-ready documentation
- Accelerates sales, engineering, and installation workflows
What It Is
String Map Auto-Generation is a software-driven process that automatically determines:
- How many modules are assigned to each string
- How strings are routed across the array layout
- Which MPPT each string connects to
- Optimal electrical grouping based on voltage and current limits
- How to minimize conductor length and voltage drop
Instead of manually defining strings using CAD tools or trial-and-error methods, the system applies algorithms that evaluate:
- Panel orientation and tilt
- Row and column structure
- DC/AC sizing ratios
- Module electrical characteristics
- Inverter MPPT limits
- Temperature-corrected voltage ranges
- Shading impact derived from Shadow Analysis
The result is a clean, code-aligned string map that directly feeds into Bill of Materials (BOM) generation, wiring diagrams, proposals, and construction documentation.
How It Works
A typical String Map Auto-Generation workflow follows these steps inside a modern solar designing platform.
1. Analyze Module Layout
The system evaluates the geometric arrangement created during Solar Designing, reading:
- Total module count
- Rows, columns, and groupings
- Tilt, azimuth, and plane orientation
This step ensures compatibility with solar layout optimization rules.
2. Ingest Electrical Constraints
Next, it pulls critical electrical data, including:
- Module Voc, Vmp, Isc, and Imp
- Inverter MPPT count and limits
- Maximum and minimum string lengths
- Temperature-based voltage correction values
These inputs are essential for accurate inverter sizing and compliance.
3. Apply Auto-Stringing Algorithm
The engine automatically:
- Clusters electrically compatible modules
- Assigns optimal string lengths
- Avoids non-contiguous module connections
- Adapts to roof boundaries defined by the Array Boundary Tool
- Optimizes wire routing distances to reduce losses
4. Map Strings to MPPTs
Each string is assigned to available MPPTs to:
- Balance current flow
- Avoid inverter overloading
- Improve overall performance ratio
5. Generate Final String Map
The system outputs:
- Color-coded string groups
- MPPT assignments
- String numbering
- Wire path recommendations
- Export-ready data for Solar Proposals and field teams
Types / Variants
1. Contiguous Auto-Stringing
Optimizes strings based on physical adjacency—ideal for residential solar and small commercial rooftops.
2. Electrical-First Auto-Stringing
Prioritizes voltage windows, shading zones, and MPPT balancing—best for shaded or electrically complex arrays.
3. Layout-Aware Auto-Stringing
Accounts for setbacks, walkways, fire pathways, and AHJ compliance.
4. Mixed-Orientation Auto-Stringing
Handles east–west, multi-tilt, and multi-plane roofs without manual intervention.
5. Utility-Scale Block Auto-Stringing
Used in ground-mount systems where strings align with combiner boxes and centralized inverters.
How It’s Measured
String Map Auto-Generation relies on measurable electrical constraints.
Voltage Window Compliance
[
V_{\text{string}} = N_{\text{modules}} \times V_{\text{module}}
]
- Must remain within inverter operating limits
- Must include temperature corrections
Current Balancing
[
I_{\text{MPPT}} = \sum I_{\text{strings}}
]
Balanced MPPT currents improve inverter efficiency and reliability.
Voltage Drop
Evaluated using conductor length and wire gauge and verified with the
String Length Constraints
- Typical residential range: 8–16 modules
- Commercial range: 12–22 modules
- Dependent on inverter and module Voc
Practical Guidance (Actionable Steps)
For Solar Designers
- Validate module electrical data before enabling auto-stringing in Solar Designing.
- Keep orientations consistent to improve grouping accuracy.
- Use Shadow Analysis to isolate shaded zones into separate strings.
For EPC & Engineering Teams
- Cross-check extreme temperature conditions to avoid over-voltage scenarios.
- Use auto-generated maps directly in construction drawings and project planning workflows.
For Proposal & Sales Teams
- Embed string maps into Solar Proposals to accelerate approvals.
- Support ROI discussions using Solar ROI Calculator outputs.
For Installers
- Follow color-coded string maps to simplify field wiring.
- Reduce installation time and rework errors.
Real-World Examples
Residential Rooftop (6 kW)
A 15-module south-facing system is auto-stringed into one optimized string.
Wire length is reduced by 18% compared to manual design.
Commercial Flat Roof (120 kW)
Auto-generation creates eight balanced strings mapped across four MPPTs, improving inverter utilization.
Utility-Scale Ground Mount (5 MW)
Over 400 strings are auto-grouped and aligned with combiner boxes—cutting engineering time by ~70%.
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