Water heater Automation: Home Assistant with Victron Forecast and Weather Station Integration

Overview

I’ve developed an enhanced Home Assistant automation for optimizing solar water heater control using Victron ESS data combined with real-time weather station measurements. The system significantly improves upon basic solar forecasting by incorporating local weather conditions.

System Setup

Hardware:

  • Victron MultiPlus II GX
  • Victron battery system (5kWh LiFePO4)
  • 2.8kW solar array
  • Electric water heater (controllable via Home Assistant)
  • Ecowitt weather station with solar irradiance sensor
  • Home Assistant with Victron integration

Key Improvements

Weather Data Integration:

  • Real-time solar irradiance (W/m²) vs forecast-only approach
  • UV index for additional solar intensity validation
  • Wind speed (improves panel cooling efficiency)
  • Rain detection for automatic power reduction
  • Temperature compensation for panel efficiency

Enhanced Algorithm:

  • Hybrid forecast combining base predictions with real-time weather correction
  • 5-tier strategy system (MINIMAL → SUPER_AGGRESSIVE)
  • Dynamic temperature targets based on actual conditions
  • Weather optimization factor: 0.2-1.3x base forecast

Results

Measurable Improvements:

  • Forecast accuracy: +15-20% (especially during variable weather)
  • Response time to weather changes: 2-5 minutes vs 30+ minutes
  • Energy efficiency: +10-15% through better condition matching
  • Reduced manual interventions: ~70% fewer adjustments needed

Example Correction:

anonymous_yaml_code.txt (26,6 KB)