Solar Forecast LangGraph

LangGraph workflow for solar forecasting with:

• Weather data agent — OpenMeteo API (free, no key required)
• Historical generation loader — From inverter-monitoring webhook
• Panel configuration schema — Azimuth, tilt, capacity, losses
• Forecast model — Physical (clear-sky + clouds) + Statistical (ML) + LLM reasoning
• Inverter-control integration — Pre-charge battery before cloudy periods
• Accuracy tracking — Feedback loop for continuous improvement

Architecture

graph TD
    A[User Request] --> B[LangGraph Workflow]
    
    B --> C[Fetch Weather<br/>OpenMeteo API]
    B --> D[Fetch History<br/>inverter-monitoring]
    
    C --> E[Train Statistical Model]
    D --> E
    
    E --> F[Generate Forecast<br/>Physical + Statistical Ensemble]
    F --> G[LLM Enhancement<br/>Weather pattern analysis]
    G --> H[Inverter-Control Hook<br/>Pre-charge decision]
    H --> I[Final Forecast Output]
    
    I --> J[Accuracy Tracking<br/>Feedback Loop]
    J -.-> K[Model Retraining - Scheduler]
    
    subgraph "Data Sources"
        C
        D
    end
    
    subgraph "Models"
        E
        F
        G
    end
    
    subgraph "Integrations"
        H
    end

Installation

# From PyPI (when published)
pip install solar-forecast-langgraph

# From source
git clone git@github.com:4alvit/solar-forecast-langgraph.git
cd solar-forecast-langgraph
python -m venv .venv
source .venv/bin/activate
pip install -e ".[dev]"
pre-commit install

Quick Start

# Copy example config and customize
cp site_config.example.py site_config.local.py
# Edit site_config.local.py with your panel details

# Run forecast (48h horizon, 30 days history)
solar-forecast --config site_config.local.py --horizon 48 --output forecast.json

Output example:

Forecast Summary:
  Site: my-solar-site
  Panel: south-roof
  Method: ensemble
  Horizon: 48 hours
  Total Energy: 42500 Wh
  Generated: 2024-01-15T10:30:00+00:00

Next 12 hours:
  2024-01-15 11:00: 1200W (1200Wh) [960-1440]
  2024-01-15 12:00: 2800W (2800Wh) [2240-3360]
  2024-01-15 13:00: 3500W (3500Wh) [2800-4200]

Configuration

Panel Configuration

from solar_forecast.config import PanelConfig, SiteConfig

panel = PanelConfig(
    name="South Roof",
    panel_id="south-roof",
    azimuth=180,  # 0=N, 90=E, 180=S, 270=W
    tilt=35,  # Degrees from horizontal
    capacity_kw=5.0,  # DC capacity
    module_count=14,
    latitude=52.37,
    longitude=4.90,
    # Optional losses
    shading_loss=0.0,
    soiling_loss=0.02,
    wiring_loss=0.01,
    module_efficiency=0.20,
    temperature_coefficient=-0.0035,
    inverter_efficiency=0.96,
    dc_ac_ratio=1.2,
)

site = SiteConfig(
    site_name="my-site",
    latitude=52.37,
    longitude=4.90,
    timezone="Europe/Amsterdam",
    panels=[panel],
)

See site_config.example.py for full example.

Forecast Methods

Inverter-Control Integration

The workflow includes a hook for pre-charging batteries before forecasted cloudy periods:

sequenceDiagram
    participant WF as LangGraph Workflow
    participant FC as Forecast
    participant IC as Inverter-Control
    
    WF->>FC: Generate 48h forecast
    FC->>WF: Forecast points with confidence
    WF->>WF: Analyze next 6h total energy
    alt Low generation (< 5kWh in 6h)
        WF->>IC: POST /api/v1/pre-charge
        IC->>IC: Increase battery target SoC
        IC-->>WF: Pre-charge initiated
    end

Enable in config:

# In site_config.local.py
INVERTER_CONTROL_URL = "http://inverter-control:8081"
INVERTER_CONTROL_API_KEY = "your-key"

Accuracy Tracking

Feedback loop for continuous improvement:

graph LR
    A[Forecast] --> B[Actual Generation]
    B --> C[Error Metrics]
    C --> D{Error > Threshold?}
    D -->|Yes| E[Flag for Review]
    D -->|No| F[Update Training Data]
    F --> G[Retrain Model]
    E --> H[Human Analysis]
    H --> G

Metrics tracked per panel:

• MAE (Mean Absolute Error)
• RMSE (Root Mean Square Error)
• MAPE (Mean Absolute Percentage Error)
• Bias (Systematic over/under prediction)

Development

Run Tests

pytest tests/ -v --cov=solar_forecast

Lint & Format

ruff check .
ruff format .

Type Check

mypy solar_forecast/

Project Structure

solar-forecast-langgraph/
├── solar_forecast/
│   ├── __init__.py          # Public exports
│   ├── config.py            # Panel/Site configuration schemas
│   ├── weather.py           # OpenMeteo client
│   ├── history.py           # Historical data loaders
│   ├── model.py             # Physical/Statistical/LLM models
│   ├── workflow.py          # LangGraph workflow
│   └── main.py              # CLI entry point
├── tests/
│   ├── test_config.py
│   ├── test_weather.py
│   ├── test_model.py
│   └── test_workflow.py
├── .github/workflows/ci.yml # CI/CD pipeline
├── pyproject.toml           # Package config
├── site_config.example.py   # Example configuration
└── README.md

Roadmap

• LLM-enhanced forecasting (weather pattern analysis)
• Automated model retraining scheduler
• Prometheus metrics export
• Grafana dashboard template
• Multi-site support in single workflow
• Battery SoC optimization (not just pre-charge)
• Shadow modeling from 3D terrain

Related Projects

• inverter-monitoring — Generation data webhook
• inverter-control — Grid-zero feed-in control

License

MIT License — see LICENSE for details.