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CLAUDE.md

This file provides guidance to Claude Code (claude.ai/code) when working with code in this repository.

Project Overview

Intelligent battery charging optimizer for Home Assistant integrated with OpenEMS and GoodWe hardware. The system optimizes battery charging based on dynamic electricity pricing from haStrom FLEX PRO tariff and solar forecasts, automatically scheduling charging during the cheapest price periods.

Hardware: 10 kWh GoodWe battery, 10 kW inverter, 9.2 kWp PV (east-west orientation) Control: BeagleBone running OpenEMS, controlled via Modbus TCP and JSON-RPC Home Assistant: PyScript-based optimization running on /config/pyscript/

Repository Structure

This repository contains versioned iterations of the battery optimization system:

/
├── v1/               # Initial implementation (threshold-based)
├── v2/               # Improved version
├── v3/               # Latest version (ranking-based optimization, sections dashboards)
├── battery_charging_optimizer.py    # Current production PyScript (v3.1.0)
├── hastrom_flex_extended.py         # Tomorrow-aware price fetcher
├── ess_set_power.py                 # Modbus FLOAT32 power control
├── EMS_OpenEMS_HomeAssistant_Dokumentation.md  # Comprehensive technical docs
└── project_memory.md                # AI assistant context memory

Important: The root-level .py files are the current production versions. Version folders contain historical snapshots and documentation from development iterations.

Core Architecture

Control Flow

14:05 daily → Fetch prices → Optimize schedule → Store in pyscript state
  ↓
xx:05 hourly → Read schedule → Check current hour → Execute action
  ↓
If charging → Enable manual mode → Set power via Modbus → Trigger automation
If auto → Disable manual mode → Let OpenEMS manage battery

Critical Components

1. Battery Charging Optimizer (battery_charging_optimizer.py)

  • Ranking-based optimization: selects N cheapest hours from combined today+tomorrow data
  • Runs daily at 14:05 (after price publication) and hourly at xx:05
  • Stores schedule in pyscript.battery_charging_schedule state with attributes
  • Conservative strategy: 20-100% SOC range, 2 kWh reserve for self-consumption

2. Price Fetcher (hastrom_flex_extended.py)

  • Fetches haStrom FLEX PRO prices with tomorrow support
  • Creates sensors: sensor.hastrom_flex_pro_ext and sensor.hastrom_flex_ext
  • Critical: Field name is t_price_has_pro_incl_vat (not standard field name)
  • Updates hourly, with special triggers at 14:05 and midnight

3. Modbus Power Control (ess_set_power.py)

  • Controls battery via Modbus register 706 (SetActivePowerEquals)
  • Critical: Uses IEEE 754 FLOAT32 Big-Endian encoding
  • Negative values = charging, positive = discharging

OpenEMS Integration Details

Controller Priority System:

  • Controllers execute in alphabetical order
  • Later controllers can override earlier ones
  • Use ctrlBalancing0 with SET_GRID_ACTIVE_POWER for highest priority
  • Direct ESS register writes can be overridden by subsequent controllers

ESS Modes:

  • REMOTE: External Modbus control active
  • INTERNAL: OpenEMS manages battery
  • Mode switching via JSON-RPC API on port 8074

Modbus Communication:

  • IP: 192.168.89.144, Port: 502
  • Register pairs use 2 consecutive registers for FLOAT32 values
  • Example: Register 2752/2753 for SET_GRID_ACTIVE_POWER

PyScript-Specific Considerations

Limitations:

  • Generator expressions with selectattr() not supported
  • Use explicit for loops instead of complex comprehensions
  • State values limited to 255 characters; use attributes for complex data

Timezone Handling:

  • PyScript datetime.now() returns UTC
  • Home Assistant stores times in local (Europe/Berlin)
  • Always use datetime.now().astimezone() for local time
  • Explicit timezone conversion required when comparing PyScript times with HA states

State Management:

# Store complex data in attributes, not state value
state.set('pyscript.battery_charging_schedule',
    value='active',  # Simple status
    new_attributes={'schedule': [...]}  # Complex data here
)

Development Commands

Testing PyScript Changes

# In Home Assistant Developer Tools → Services:
service: pyscript.reload

Manual Schedule Calculation

# In Home Assistant Developer Tools → Services:
service: pyscript.calculate_charging_schedule

Manual Execution Test

# In Home Assistant Developer Tools → Services:
service: pyscript.execute_charging_schedule

Check Schedule State

# In Home Assistant Developer Tools → States, search for:
pyscript.battery_charging_schedule

OpenEMS Logs (on BeagleBone)

tail -f /var/log/openems/openems.log

Key Integration Points

Required Home Assistant Entities

Input Booleans:

  • input_boolean.battery_optimizer_enabled - Master enable/disable
  • input_boolean.goodwe_manual_control - Manual vs auto mode
  • input_boolean.battery_optimizer_manual_override - Skip automation

Input Numbers:

  • input_number.battery_capacity_kwh - Battery capacity (10 kWh)
  • input_number.battery_optimizer_min_soc - Minimum SOC (20%)
  • input_number.battery_optimizer_max_soc - Maximum SOC (100%)
  • input_number.battery_optimizer_max_charge_power - Max charge power (5000W)
  • input_number.charge_power_battery - Target charging power

Sensors:

  • sensor.esssoc - Current battery SOC
  • sensor.openems_ess0_activepower - Battery power
  • sensor.openems_grid_activepower - Grid power
  • sensor.openems_production_activepower - PV production
  • sensor.energy_production_today / sensor.energy_production_today_2 - PV forecast (east/west)
  • sensor.energy_production_tomorrow / sensor.energy_production_tomorrow_2 - PV tomorrow

Existing Automations

Three manual control automations exist (in Home Assistant automations.yaml):

  • Battery charge start (ID: 1730457901370)
  • Battery charge stop (ID: 1730457994517)
  • Battery discharge

Important: These automations are used by the optimizer, not replaced. The PyScript sets input helpers that trigger these automations.

Dashboard Variants

Multiple dashboard configurations exist in v3/:

  • Standard (battery_optimizer_dashboard.yaml): Detailed view with all metrics
  • Compact (battery_optimizer_dashboard_compact.yaml): Balanced mobile-friendly view
  • Minimal (battery_optimizer_dashboard_minimal.yaml): Quick status check
  • Sections variants: Modern HA 2024.2+ layouts with auto-responsive behavior

All use maximum 4-column layouts for mobile compatibility.

Required HACS Custom Cards:

  • Mushroom Cards
  • Bubble Card
  • Plotly Graph Card
  • Power Flow Card Plus
  • Stack-in-Card

Common Troubleshooting

Battery Not Charging Despite Schedule

Symptom: Schedule shows charging hour but battery stays idle Causes:

  1. Controller priority issue - another controller overriding
  2. Manual override active (input_boolean.battery_optimizer_manual_override == on)
  3. Optimizer disabled (input_boolean.battery_optimizer_enabled == off)

Solution: Check OpenEMS logs for controller execution order, verify input boolean states

Wrong Charging Time (Off by Hours)

Symptom: Charging starts at wrong hour Cause: UTC/local timezone mismatch in PyScript Solution: Verify all datetime operations use .astimezone() for local time

No Tomorrow Prices in Schedule

Symptom: Schedule only covers today Cause: Tomorrow prices not yet available (published at 14:00) Solution: Normal before 14:00; if persists after 14:05, check sensor.hastrom_flex_pro_ext attributes for tomorrow_available

Modbus Write Failures

Symptom: Modbus errors in logs when setting power Cause: Incorrect FLOAT32 encoding or wrong byte order Solution: Verify Big-Endian format in ess_set_power.py, check OpenEMS Modbus configuration

Data Sources

haStrom FLEX PRO API:

  • Endpoint: http://eex.stwhas.de/api/spotprices/flexpro?start_date=YYYYMMDD&end_date=YYYYMMDD
  • Price field: t_price_has_pro_incl_vat (specific to FLEX PRO tariff)
  • Supports date range queries for multi-day optimization

Forecast.Solar:

  • Two arrays configured: East (90°) and West (270°) on flat roof
  • Daily totals available, hourly breakdown simplified

InfluxDB2:

  • Long-term storage for historical analysis
  • Configuration in Home Assistant configuration.yaml

File Locations in Production

When this code runs in production Home Assistant:

/config/
├── pyscripts/
│   ├── battery_charging_optimizer.py    # Main optimizer
│   ├── hastrom_flex_extended.py         # Price fetcher
│   └── ess_set_power.py                 # Modbus control
├── automations.yaml                      # Contains battery control automations
├── configuration.yaml                    # Modbus, InfluxDB configs
└── dashboards/
    └── battery_optimizer.yaml            # Dashboard config

Algorithm Overview

Ranking-Based Optimization (v3.1.0):

  1. Calculate needed charging hours: (target_SOC - current_SOC) × capacity ÷ charge_power
  2. Combine today + tomorrow price data into single dataset
  3. Score each hour: price - (pv_forecast_wh / 1000)
  4. Sort by score (lowest = best)
  5. Select top N hours where N = needed charging hours
  6. Execute chronologically

Key Insight: This approach finds globally optimal charging times across midnight boundaries, unlike threshold-based methods that treat days separately.

Version History Context

  • v1: Threshold-based optimization, single-day planning
  • v2: Enhanced with better dashboard, improved error handling
  • v3: Ranking-based optimization, tomorrow support, modern sections dashboards

Each version folder contains complete snapshots including installation guides and checklists for that iteration.

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