A control unit for an inverter connected to a battery, charged by a balcony solar station, receiving electricity power data via LoRa radio.
LoraDTU controls the inverter on the basis of the values read from the smart meter and transmitted via Lora so that the sum of current consumption and current feed-in is approximately zero (‘zero feed-in’). This is to ensure that only as much electricity is drawn from the battery as is currently needed in the household.
Only during the day, when the battery is fully charged, the inverter is ramped up to feed excess energy (that can no longer be stored in the battery) into the grid.
LoraDTU is based on OpenDTU (by the way, a fantastic project). The aim of the redevelopment was to control the inverter output depending on the current power demand in order to optimise the use of the battery integrated in the system. All adjustments were only made for a special system with a Hoymiles HM-800 and a 24 V LiFePO4 battery.
The current power requirement is read from a smart meter and transmitted to the DTU via LoRa. (The corresponding projects can be found on Github under Ausleser-fuer-Stromzaehler-Smartmeter-Landis-Gyr-E450 and Ausleser-fuer-Stromzaehler-Smartmeter-Ensor-eRS801.)
In contrast to OpenDTU, the project LoraDTU is not actively maintained and updated - it is more a proof of concept. (Nevertheless, any bug reports, suggestions for improvement and other comments on LoraDTU are welcome, please contact the autor C-E via k-l-p@gmx.de.)
LoraDTU is available free of charge under the open source licence (GNU General Public License version 2). Any warranty beyond that for fraudulently concealed defects is excluded. Any liability for errors, damage and consequential damage is excluded, with the exception of wilful intent and gross negligence. Use at your own risk.
Main screen of LoraDTU's web interface ("Live View"):
More screenshots of the frontend for LoraDTU can be found here: Screenshots
| Model | Required RF Module | DC Inputs | MPP-Tracker | AC Phases |
|---|---|---|---|---|
| Hoymiles HM-800 | NRF24L01+ | 2 | 2 | 1 |
- Read live data from inverter
- Switch display off or on
- Switch between manual mode (set the current inverter limit manually) and automatic mode (set the current inverter limit automatically based on real-time smartmeter data received via Lora)
- Show the current inverter limit
- Show inverter internal event log
- Show inverter information like firmware version, firmware build date, hardware revision and hardware version
- Function to turn the inverter off and on
- WebApp with visualization of current data
- Firmware upgrade using the web UI
- English, german and french web interface
- Displays (SSD1306, SH1106, PCD8544)
- Status LEDs
- Configuration management (export / import configurations)
- Dark Theme
- Uses ESP32 microcontroller and NRF24L01+
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The microcontroller part
- Build with Arduino PlatformIO Framework for the ESP32
- Uses a fork of ESPAsyncWebserver
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The WebApp part
- Build with Vue.js
- Source is written in TypeScript
Sample Picture:
The PLUS sign is IMPORTANT! There are different variants available, with antenna on the printed circuit board or external antenna.
Sample picture:
Buy your hardware from a trusted source, at best from a dealer/online shop in your country where you have support and the right to return non-functional hardware. When you want to buy from Amazon, AliExpress, eBay etc., take note that there is a lot of low-quality or fake hardware offered. Read customer comments and ratings carefully!
A heavily incomplete list of trusted hardware shops in germany is:
This list is for your convenience only, the project is not related to any of these shops.
Use a power suppy with 5 V and 1 A. The USB cable connected to your PC/Notebook may be powerful enough or may be not.
Its possible to change all the pins of the NRF24L01+ module, the Display, the LED etc. The recommend way to change the pin assignment is by creating a custom device profile. It is also possible to create a custom environment and compile the source yourself. This can be achieved by copying one of the [env:....] sections from 'platformio.ini' to 'platformio_override.ini' and editing the 'platformio_override.ini' file and add/change one or more of the following lines to the 'build_flags' parameter:
-DHOYMILES_PIN_MISO=12
-DHOYMILES_PIN_MOSI=13
-DHOYMILES_PIN_SCLK=14
-DHOYMILES_PIN_IRQ=0
-DHOYMILES_PIN_CE=4
-DHOYMILES_PIN_CS=15
-DLED1=25It is recommended to make all changes only in the 'platformio_override.ini', this is your personal copy.
- Install Visual Studio Code (from now named "vscode")
- In Visual Studio Code, install the PlatformIO Extension
- Install git and enable git in vscode - git download - Instructions
- Clone this repository (you really have to clone it, don't just download the ZIP file. During the build process the git hash gets embedded into the firmware. If you download the ZIP file a build error will occur): Inside vscode open the command palette by pressing
CTRL+SHIFT+P. Entergit clone, add the repository-URLhttps://github.com/c-e-github/LoraDTU. Next you have to choose (or create) a target directory. - In vscode, choose File --> Open Folder and select the previously downloaded source code. (You have to select the folder which contains the "platformio.ini" and "platformio_override.ini" file)
- Adjust the COM port in the file "platformio_override.ini" for your USB-to-serial-converter. It occurs twice:
- upload_port
- monitor_port
- Select the arrow button in the blue bottom status bar (PlatformIO: Upload) to compile and upload the firmware. During the compilation, all required libraries are downloaded automatically.
- Under Linux, if the upload fails with error messages "Could not open /dev/ttyUSB0, the port doesn't exist", you can check via
ls -la /dev/tty*to which group your port belongs to, and then add your user this group viasudo adduser <yourusername> dialout(if you are usingarch-linuxuse:sudo gpasswd -a <yourusername> uucp, this method requires a logout/login of the affected user). - For OpenDTU there are two videos showing these steps - for LoraDTU this should be analog:
- After the initial flashing of the microcontroller, an Access Point called "LoraDTU-********" is opened (* is replaced with numbers). Connect to this WLAN. The default password is "loradtu1".
- Use a web browser to open the address http://192.168.4.1
- Navigate to Settings --> Network Settings. The username to access the config menu is "admin" and the password is the same as for accessing the Access Point (default: "loradtu1"). After you have access, you can enter your WiFi credentials, i.e. the name of your WLAN ("SSID") and your password.
- LoraDTU then simultaneously connects to your WiFi AP with these credentials. Navigate to Info --> Network and look into section "Network Interface (Station)" for the IP address received via DHCP.
- If your WiFi AP uses an allow-list for MAC-addresses, please be aware that the ESP32 has two different MAC addresses for its AP and client modes, they are also listed at Info --> Network.
- When LoraDTU is connected to a configured WiFI AP, the "LoraDTU-********" Access Point is closed after 3 minutes.
- LoraDTU needs access to a working NTP server to get the current date & time. Both are sent to the inverter with each request. Default NTP server is pool.ntp.org. If your network has different requirements please change accordingly (Settings --> NTP Settings).
- Add your inverter in the inverter settings (Settings --> Inverter Settings). You need to enter the serial number of the inverter.
Once you have your LoraDTU running and connected to WLAN, you can do further updates through the web interface. Navigate to Settings --> Firmware upgrade and press the browse button. Select the firmware file from your local computer.
You'll find the firmware file (after a successful build process) under .pio/build/ttgo-lora32-v21/firmware.bin.
After the successful upload, the LoraDTU immediately restarts into the new firmware.
A documentation of the Web API can be found here: Web-API Documentation
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Building the WebApp
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The WebApp can be build using yarn
cd \PlatformIO\Projects\LoraDTU\webapp yarn install yarn build
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The updated output is placed in the 'webapp_dist' directory
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It is only necessary to build the webapp when you made changes to it
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For testing/developing you can use
cd \PlatformIO\Projects\LoraDTU\webapp yarn dev
and open http://localhost:5173/
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Building the microcontroller firmware
- Visual Studio Code with the PlatformIO Extension is required for building
- First: the inverter has to be connected to the battery, the inverter LED must light up.
- When there is no data received from the inverter(s) - try to reduce the distance between the LoraDTU and the inverter
- Under Settings -> DTU Settings you can increase the transmit power "PA level". Default is "minimum".
- The NRF24L01+ needs relatively much current. With bad power supply (and especially bad cables!) a 10 µF capacitor soldered directly to the NRF24L01+ board connector brings more stability (pin 1+2 are the power supply). Note the polarity of the capacitor…
- You can try to use an USB power supply with 1 A or more instead of connecting the ESP32 to the computer.
- Try a different USB cable. Once again, a stable power source is important. Some USB cables are made of much plastic and very little copper inside.
- Double check that you have a radio module NRF24L01+ with a plus sign at the end. NRF24L01 module without the plus are not compatible with this project.
- There is no possibility of auto-discovering the inverters. Double check you have entered the serial numbers of the inverters correctly.
- LoraDTU needs access to a working NTP server to get the current date & time.
- Make sure to connect the inverter only to one DTU (Original, Ahoy, OpenDTU, LoraDTU doesn't make a difference). If you query a inverter by multiple DTUs you will get strange peaks in your values.