1. Application Overview

The project open-source code are available on the GitHub page
and pre-built firmware binaries are available on the GitHub Releases page. Simply download, extract, and flash using the included scripts - no compilation required!

1.1 Purpose

ACRouter is an open-source controller for automatically redirecting excess solar energy to resistive loads (such as water heaters) instead of exporting it to the grid. It also optimizes energy consumption during peak and off-peak tariff periods with consumption limits.

Main Goal: Minimize energy export to the grid by dynamically controlling load power based on the current balance between production and consumption. Reduce costs of electricity consumption from the grid.

Key Benefits:

✅ Automatic management of excess solar energy
✅ Optimization of off-peak tariffs and consumption limits
✅ Reduced electricity costs (self-consumption)
✅ Lower equipment costs. No batteries required for energy storage
✅ Export protection (ECO mode)
✅ Flexible configuration via web interface
✅ Multiple operating modes supported
✅ Control of multiple consumption devices. Dimmers and relays.
✅ Open source code

1.2 Features

Measurement and Monitoring

Grid voltage measurement (ZMPT107 AC voltage sensor)
Current measurement at 3 points (SCT-013/ACS-712 current sensors):
Load current (Load)
Grid current (Grid) - import/export detection
Solar generation current (Solar)
Active power calculation in real time
Update frequency: 200 ms (5 times per second)
Measurement accuracy: 12-bit ADC with DMA (up to 80kHz on 8 channels)

Load Control

Phase-angle dimmer control (TRIAC dimmer)
Smooth power adjustment 0-100%
Synchronization with zero-cross detector
Support for up to 2 dimmer channels, expandable to available GPIO
Relay outputs (ROADMAP: Develop Phase 2)
2 independent relays, expandable to available GPIO
Programmable polarity (Active HIGH/LOW)

Control Algorithms

Proportional controller (P-controller)
Balancing P_grid → 0
Adjustable gain coefficient (Kp)
Operating modes: OFF, AUTO, ECO, OFFGRID, MANUAL, BOOST
Anti-flickering - smoothing of dimmer changes

Communication

WiFi: AP mode (192.168.4.1) + STA mode (connection to router)
WebServer: REST API + Material UI interface
Serial Console: Command line for configuration (115200 baud)
OTA Updates: Over-the-air firmware updates (Phase 2)

Configuration and Storage

NVS (Non-Volatile Storage):
ACRouter settings (mode, Kp, setpoint)
WiFi configuration (SSID, password)
Hardware configuration (GPIO pins, sensor types)
Web interface:
Dashboard with real-time metrics
WiFi settings page
Hardware configuration page
Operating mode selection
Serial terminal (console):
Real-time metrics display
Command line for hardware and device parameter configuration
Operating mode selection

1.3 Functionality

Automatic Control

Power measurement:
Voltage and currents are measured every 200 ms
RMS value calculation (root mean square)
Active power calculation (P = U × I × cos φ)
Balance determination:
P_solar = power from solar panels
P_load = current house consumption
P_grid = import/export to grid
P_dimmer = controlled load power
Control algorithm:
Goal: P_grid → 0 (zero export/import)
Proportional controller: ΔDimmer = Kp × P_grid
Applied to dimmer with limits 0-100%

Monitoring via Web Interface

Real-time metrics:
Grid voltage (V)
Currents: Grid, Solar, Load (A)
Power: Grid, Solar, Load, Dimmer (W)
Dimmer level (%)
Current operating mode
System information:
Firmware version
Uptime
Heap memory (free RAM)
WiFi RSSI (signal level)

Configuration via web-interface

Operating mode selection (6 buttons)
Manual dimmer control (slider 0-100%)
WiFi setup (network scanning, connection)
GPIO pin and sensor type configuration
Sensor calibration (multiplier, offset)
Device reboot

1.4 Operating Modes

OFF (0) - Disabled

Description: Dimmer is completely disabled (0%), system is inactive.

Usage:
- Maintenance
- Load disconnection
- Sensor testing without control

Behavior:
- Dimmer level = 0%
- Measurements continue (200 ms)
- Web interface is available
- Serial commands work

AUTO (1) - Automatic (Solar Router)

Description: Main Solar Router mode. Automatic balancing of P_grid → 0.

Algorithm:

cpp

// Every 200 ms
P_error = P_grid;  // Positive = import, negative = export
delta = Kp * P_error;  // Proportional controller
dimmer_level += delta;
dimmer_level = constrain(dimmer_level, 0, 100);

Behavior:
- P_grid > 0 (import from grid) → Increase dimmer (more load)
- P_grid < 0 (export to grid) → Decrease dimmer (less load)
- P_grid ≈ 0 → Dimmer stabilized

Settings:
- Kp (gain) - gain coefficient (default: 0.05)
- Higher Kp = faster response, but possible oscillations
- Lower Kp = smoother, but slower
- setpoint - target P_grid value (usually 0 W)

Example:

python

Initial state:
  P_solar = 2000 W
  P_load = 500 W
  P_grid = -1500 W (export!)
  Dimmer = 0%

After 5 seconds (AUTO mode, Kp=0.05):
  P_solar = 2000 W
  P_load = 500 W
  Dimmer = 75% (~1500 W to water heater)
  P_grid = 0 W ✅ (balance achieved)

ECO (2) - Economy (Anti-Export)

Description: Prevents export to the grid. Import is allowed, but export is prohibited.

Algorithm:

cpp

if (P_grid < 0) {  // Export to grid
    // Decrease dimmer (reduce load)
    delta = Kp * P_grid;  // Negative delta
    dimmer_level += delta;
} else {
    // Import is allowed, do not increase dimmer
    // Keep current level
}
dimmer_level = constrain(dimmer_level, 0, 100);

Behavior:
- P_grid < 0 (export) → Decrease dimmer (avoid export)
- P_grid > 0 (import) → Do not change dimmer (import is allowed)
- P_grid = 0 → Dimmer is stable

Applications:
- Export tariff is unfavorable or absent
- Need to use only excess energy
- Export protection when there is no grid export contract

Example:

python

Situation 1: Solar excess
  P_solar = 3000 W
  P_load = 1000 W
  P_grid = -500 W (export)
  → ECO mode will increase dimmer by ~500 W → P_grid = 0

Situation 2: Solar shortage
  P_solar = 500 W
  P_load = 1000 W
  P_grid = +500 W (import)
  → ECO mode will NOT change dimmer (import is allowed)

OFFGRID (3) - Off-Grid

Description: Mode for autonomous systems with batteries. Uses excess solar energy for the load.

Algorithm:

cpp

// Balance by solar panel current
P_available = P_solar - P_load;  // Available power
if (P_available > 0) {
    // There is solar excess → increase dimmer
    dimmer_level = map(P_available, 0, P_dimmer_max, 0, 100);
} else {
    // No excess → turn off dimmer (save battery)
    dimmer_level = 0;
}

Behavior:
- Uses only solar energy
- Does not consider P_grid (no grid)
- Priority: main load → batteries → dimmer
- Dimmer works only when there is solar excess

Applications:
- Systems without grid connection
- Solar panels + batteries
- Maximize solar energy usage

Example:

python

Daytime (sunny):
  P_solar = 1500 W
  P_load = 800 W
  P_available = 700 W
  → Dimmer = 50% (~700 W to water heater)
  → Battery is not discharging

Evening (no sun):
  P_solar = 0 W
  P_load = 800 W (from battery)
  → Dimmer = 0% (battery saving)

MANUAL (4) - Manual Mode

Description: Dimmer is set to a fixed level (no automation).

Behavior:
- Dimmer level is set by user (0-100%)
- No automatic regulation
- Level is maintained until manually changed

Applications:
- Load testing
- Night tariff (set to 100%)
- Temperature control (set to 50%)
- System debugging

Settings:
- manual_level - dimmer level (0-100%)

Example:

bash

# Via Serial commands
set-manual 75        # Set dimmer to 75%
set-mode 4           # Switch to MANUAL mode

# Via web interface
1. Select MANUAL mode
2. Move slider to 75%
3. Click "Apply"

BOOST (5) - Maximum Power

Description: Dimmer at 100% (forced heating).

Behavior:
- Dimmer level = 100% (constant)
- Ignores all sensors
- Maximum power to load

Applications:
- Fast water heater heating
- Using cheap tariff
- Emergency mode

Warnings:
- ⚠️ High grid consumption
- ⚠️ Possible load overheating
- ⚠️ Monitor temperature manually

Example:

python

Night tariff (23:00-07:00):
  1. Switch to BOOST mode
  2. Water heater heats at maximum
  3. In the morning switch back to AUTO

Result:
  Heating from cheap tariff
  Daytime operation in AUTO mode (solar)

1.5 Mode Comparison Table

Mode	Dimmer Control	P_grid Balance	Import Allowed	Export Allowed	Use Case
OFF	0% (fixed)	❌ No	N/A	N/A	Maintenance
AUTO	Automatic	✅ Yes (→ 0)	✅ Yes	✅ Yes	Standard Solar Router
ECO	Auto (anti-export)	⚠️ Partial	✅ Yes	❌ No	No export contract
OFFGRID	Auto (solar only)	❌ No	N/A	N/A	Off-grid systems
MANUAL	Fixed (user)	❌ No	✅ Yes	✅ Yes	Testing / Night tariff
BOOST	100% (fixed)	❌ No	✅ Yes	❌ No	Fast heating

1.6 Use Case Scenarios

Scenario 1: Standard Solar Router

Equipment:
- 3 kW solar panels
- Sensors: Solar, Grid, Load, Voltage
- Load: 2 kW water heater

Mode: AUTO

Operation:
1. During the day there is excess solar energy
2. P_grid is negative (export to grid)
3. Controller increases dimmer → water heater heating
4. P_grid balances → 0 (zero export/import)
5. All solar energy is used locally

Scenario 2: Export Protection (ECO)

Equipment:
- 5 kW solar panels
- No grid export contract
- Sensors: Solar, Grid, Voltage
- Load: Water heater element

Mode: ECO

Operation:
1. During the day solar excess → export to grid begins
2. ECO mode detects P_grid < 0
3. Dimmer increases → water heating
4. Export prevented (P_grid ≥ 0)
5. Evening sun sets → dimmer decreases
6. Import allowed (grid purchase when needed)

Scenario 3: Autonomous System (OFFGRID)

Equipment:
- 2 kW solar panels
- 10 kWh batteries
- No grid connection
- Sensors: Solar, Load, Voltage
- Load: Tank heating element

Mode: OFFGRID

Operation:
1. System is autonomous (no grid)
2. During the day solar excess → water heating
3. At night heating element is off (no sun)
4. Batteries are used for main load
5. Maximize solar energy usage

Scenario 4: Night Tariff + Water Heater

Equipment:
- Two-tariff meter (day/night)
- Sensors: Grid, Voltage
- Load: Water heater

Mode: MANUAL (night) / OFF (day)

Operation:
1. Night (23:00-07:00): MANUAL 100% (cheap tariff)
2. Day (07:00-23:00): OFF (expensive tariff)
3. Programmable via schedule (Phase 2: SCHEDULE mode)

1.7 System Architecture

python

┌─────────────────────────────────────────────────────────────┐
│                      ESP32 Controller                        │
│                                                               │
│  ┌─────────────┐  ┌──────────────┐  ┌────────────────────┐ │
│  │ PowerMeter  │  │   Router     │  │  DimmerHAL         │ │
│  │   ADC       │→ │  Controller  │→ │  (Zero-cross)      │ │
│  └─────────────┘  └──────────────┘  └────────────────────┘ │
│         ↓                                      ↓             │
│    Measurements                           TRIAC Control      │
│    (200ms cycle)                          (50Hz sync)        │
│                                                               │
│  ┌──────────────────────────────────────────────────────┐   │
│  │              WiFi Manager                            │   │
│  │  ┌──────────────┐  ┌────────────────────────────┐   │   │
│  │  │ AP Mode      │  │ WebServer (Material UI)    │   │   │
│  │  │ 192.168.4.1  │  │ + REST API                 │   │   │
│  │  └──────────────┘  └────────────────────────────┘   │   │
│  └──────────────────────────────────────────────────────┘   │
│                                                               │
│  ┌──────────────────────────────────────────────────────┐   │
│  │         ConfigManager + HardwareConfigManager        │   │
│  │                    (NVS Storage)                      │   │
│  └──────────────────────────────────────────────────────┘   │
└─────────────────────────────────────────────────────────────┘
        ↑                              ↓
   ┌────────────┐             ┌──────────────────┐
   │  Sensors   │             │  Dimmer Output   │
   ├────────────┤             ├──────────────────┤
   │ ZMPT107    │             │  TRIAC           │
   │ (Voltage)  │             │  (0-100%)        │
   │ SCT-013    │             │                  │
   │ ACS-712    │             │  Load:           │ 
   │ (Current)  │             │  Heater/Boiler   │
   │ x3 sensors │             │  (up to 2kW)     │
   └────────────┘             └──────────────────┘

1.8 Target Audience

ACRouter is designed for:

DIY enthusiasts - build a Solar Router yourself
Homeowners with solar panels - optimize self-consumption
Developers - foundation for custom projects (open source)
Educational projects - learning IoT, energy management, ESP32
Small businesses - reduce electricity costs

1.9 Limitations and Warnings

⚠️ IMPORTANT:

Electrical Safety
Working with 230V mains voltage is dangerous
Electrician qualification is required
Galvanic isolation of sensors is mandatory
RCD (Residual Current Device) is mandatory
Load Compatibility for dimmers
Suitable only for resistive loads (heating elements, heaters)
NOT suitable for inductive loads (motors, transformers)
NOT suitable for electronics (LED drivers, power supplies)
Power
Maximum is limited by TRIAC module (usually 2 kW)
Cooling is required for high loads
Overheat protection is recommended
Measurement Accuracy
Calibration is required for accuracy
Error ±5-10% with basic settings
Temperature affects sensors
Grid Requirements
Stable grid frequency (50/60 Hz)
Quality voltage without strong fluctuations
Zero-cross detector is critical for TRIAC

ACrouter

1. Application Overview

1.1 Purpose

Key Benefits:

1.2 Features

Measurement and Monitoring

Load Control

Control Algorithms

Communication

Configuration and Storage

1.3 Functionality

Automatic Control

Monitoring via Web Interface

Configuration via web-interface

1.4 Operating Modes

OFF (0) - Disabled

AUTO (1) - Automatic (Solar Router)

ECO (2) - Economy (Anti-Export)

OFFGRID (3) - Off-Grid

MANUAL (4) - Manual Mode

BOOST (5) - Maximum Power

1.5 Mode Comparison Table

1.6 Use Case Scenarios

Scenario 1: Standard Solar Router

Scenario 2: Export Protection (ECO)

Scenario 3: Autonomous System (OFFGRID)

Scenario 4: Night Tariff + Water Heater

1.7 System Architecture

1.8 Target Audience

1.9 Limitations and Warnings