Fronius GEN24 Monitor

Live solar power dashboard for the Waveshare ESP32-S3-Touch-AMOLED-1.75 display board. Polls the Fronius GEN24 Symo inverter's local REST API every 5 seconds and renders power data across five touch-navigable screens.

Hardware

Component	Detail
MCU	ESP32-S3R8 (240 MHz, 8 MB OPI PSRAM, 16 MB flash)
Display	CO5300 QSPI AMOLED, 466×466 px, 1.75"
Touch	CST9217 I2C capacitive
PMIC	AXP2101 (board LiPo management)

Screens

Navigation is by swipe gestures on the touch screen. The screen layout is:

         [STATUS]
            ↕  swipe up/down
         [PHASES]
            ↕  swipe up/down
[CLOCK] ←→ [MAIN]              (left/right swipe)
            ↕  swipe up/down
           [PV]

Main screen

The default screen after boot.

• Green arc (270° sweep around the edge) — solar PV generation. Full scale is the configured solar maximum; the arc fills proportionally.
• Yellow — current PV output in watts (top).
• Yellow, smaller — inverter AC output watts.
• Blue — household consumption in watts.
• Blue — battery state of charge (%). Colour changes to green while charging and red while discharging.
• Grid — net grid power (centre bottom). Grey when balanced (< 20 W), green when importing, red when exporting.
• "No data" — shown in red if the inverter has not responded after 3 consecutive poll failures.

Clock screen

Swipe left or right from Main.

• Analog clock face — hour, minute (white), and second (orange) hands with 12 hour-marker dots.
• Blue arc — battery state of charge, same 270° geometry as the solar arc. Arc and the small SOC label at the bottom change colour to match charge state (green = charging, red = discharging).

PV screen

Swipe down from Clock.

• Identical analog clock face.
• Green arc — solar PV output (same scale as the Main screen arc).
• Green label at the arc gap — current PV watts.

Phases screen

Swipe up from Main.

• Green arc — solar PV output (same scale and colour as Main).
• Yellow label — current PV watts.
• L1 / L2 / L3 — per-phase grid power in watts, signed. Colour per phase:
  • Grey — near zero (< 20 W)
  • Green — importing from grid
  • Red — exporting to grid
• Data comes from the Fronius Smart Meter via GetMeterRealtimeData.cgi. If the meter is unreachable, all phase labels show -- W.

Status screen

Swipe up from Phases.

• Arc — board LiPo battery level (0–100%). Colour: blue = idle/full, green = charging, red = low.
• Battery % and charge state label (Charging / Discharging / Low battery / No battery).
• Wi-Fi IP address — the address to use for OTA updates.
• RSSI — signal strength in dBm with quality rating (Excellent / Good / Fair / Poor).

First-time installation

Prerequisites

• PlatformIO — install the VS Code extension or the CLI (pip install platformio).
• USB-C cable connected to the board's USB port.

Steps

1. Clone the repository

git clone https://github.com/pmajor021/fronius_gen24_v2.git
cd fronius_gen24_v2

2. Build and flash

pio run --target upload

PlatformIO downloads all dependencies on the first run. Upload speed is 921600 baud; the board is detected automatically via USB CDC.

3. Open the serial monitor (optional but useful on first boot)

pio device monitor

4. Connect to the setup portal

On first boot — or whenever saved WiFi credentials are missing — the board opens a WiFi access point named Fronius-Monitor.

1. On your phone or laptop, connect to the Fronius-Monitor WiFi network.
2. A captive portal will open automatically, or navigate to http://192.168.4.1.
3. Click Configure WiFi.
4. Fill in:
   • WiFi network — your home network SSID and password.
   • Inverter IP Address — the local IP of your Fronius GEN24 inverter (e.g. 192.168.1.120). Find it in the Fronius Solar.web app or your router's DHCP table.
   • Solar Max Watts — the peak DC input capacity of your inverter (e.g. 6000). This sets the full-scale value of the solar arc.
5. Click Save.

The board reboots, connects to your WiFi, and begins polling the inverter. The boot screen displays the assigned IP address for 4 seconds before switching to the Main screen.

The portal does not reappear on subsequent boots unless credentials are lost or a factory reset is performed.

Factory reset

To clear all saved settings and re-enter the setup portal:

1. Hold a finger on the touch screen.
2. Power on (or reset) the board while keeping the touch held.
3. Hold for 3 seconds after the board starts.
4. Release — the board clears NVS storage and WiFi credentials, then opens the Fronius-Monitor portal.

Timezone

Edit include/config.h and rebuild:

#define TZ_OFFSET_SEC   3600   /* seconds east of UTC — e.g. 3600 for CET  */
#define DST_OFFSET_SEC  3600   /* daylight saving offset — e.g. 3600 for CEST */

OTA firmware update

After the board is on your network, you can update the firmware without a USB cable.

1. Build the new firmware:

pio run

The output binary is at .pio/build/esp32s3_amoled/firmware.bin.

2. Open the OTA page in a browser:

http://<device-ip>/update

The device IP is shown on the Status screen, or in the serial monitor at boot:

[ota] update page at http://192.168.x.x/update

3. Click Firmware, select .pio/build/esp32s3_amoled/firmware.bin, then click Update.

The board reboots automatically after a successful upload. All NVS settings (WiFi credentials, inverter IP, solar max) are preserved across OTA updates.

Navigating to the root address http://<device-ip>/ also redirects to the update page.

Build reference

# Build only
pio run

# Build + flash + open serial monitor
pio run --target upload && pio device monitor

# Build filesystem image only
pio run --target buildfs

Serial monitor diagnostics

Open at 115200 baud. Normal startup looks like:

[boot] Fronius Gen24 Monitor starting
[boot] display init done
[boot] UI init done
[wifi] connected, local IP: 192.168.x.x
[ota] update page at http://192.168.x.x/update
[fronius] task started, polling 192.168.x.x every 5000 ms
[fronius] response code: 200
[fronius] OK  solar=2340 W  inv=2290 W  load=850 W  grid=+1490 W  soc=78%
[fronius] phases: L1=500 L2=-300 L3=-450 W

Log line	Diagnosis
response code: -1 or connection error	Wrong inverter IP, inverter unreachable, or WiFi dropped
response code: 200 but JSON parse error	Fronius returned an HTML error page instead of JSON
Body.Data.Site not found	API response structure differs — keys are printed to help diagnose
phases response: 404	Smart meter endpoint not available on this inverter
phases: Body.Data[0] not found	Meter found but indexed differently — check meter DeviceId
data state changed → VALID never appears	All fetch attempts failing — check the fronius lines above

Fronius API endpoints used

Endpoint	Data
GET /solar_api/v1/GetPowerFlowRealtimeData.fcgi	PV watts, consumption, grid, battery SOC
GET /solar_api/v1/GetMeterRealtimeData.cgi?Scope=System	Per-phase grid power (L1/L2/L3)
GET /solar_api/v1/GetStorageRealtimeData.cgi?Scope=System	Battery SOC fallback (older firmware)

The inverter is polled every 5 seconds. Per-phase data requires a Fronius Smart Meter connected to the inverter.