Photovoltaic dashboard with Grafana

I have a SolarEdge Inverter which is monitored by a energy meter (SolarEdge SE-MTR-3Y-400V-A). The energy meter gets measurements from the inverter and measures voltage and current at the house entry point.

SolarEdge provide a monitoring service and a mobile app to monitor the system. An example is shown here:

To be able to monitor and evaluate the measurements by myself I use the following applications:
  • mbmd - to read the measurements from the inverter and energy meter
  • nodered - to calculate some derived values 
  • mqtt - to "transport" the measurements between the apps
  • telegraf - to write the measurements into influxdb
  • influxdb - to store the measurements
  • grafana - to display the measurements

The result looks like this (a snapshot is available here):



The mbmd reads the measurements from the inverter and (via the inverter) from the energy meter.
pi@racknode:/etc $ more mbmd.yaml
# REST api, use to restrict to localhost

# mqtt config
  broker: my.mqtt.server:1883
  topic: mbmd
#  user:
#  password:
  clientid: mbmd
  qos: 0
  homie: ""
  # homie: homie

# adapters are referenced by device
- device: inverter.ip.addr:1502

# list of devices
- name: inverter
  type: SE
  id: 1
  subdevice: 0 # use subdevice to access SunSpec subdevices
- name: powermeter
  type: SE
  id: 1
  subdevice: 1 # use subdevice to access SunSpec subdevices


To calculate the "self consumption" and split the measured power in Import/Export I create a Node-Red flow:

Here is the corresponding flow code.


The telegraf is configured to transfer the mqtt messages to the influxdb. 

The config is available here.


A snapshot of the dashboard is available here and also the dashboard.json is available.


HP MFP M754DN Fix "Scan to Network" error

My multifunction printer HP MFP M754DN has the ability to scan to a network folder. The target folder is provided by a samba server running CentOS8. It works with out problem but stops to be able to access the network folder some weeks ago. 

Testing the connection on the webgui results in the message: "Cannot connect to the network folder. Ensure the shared folder name is correct."

To fix it I have added the following lines in the smb.conf file on the samba server.
server min protocol = NT1    
min protocol = NT1
A further analysis of my last update activities showed that this was related to the update of the samba package from samba-4.10.4-101.el8_1.x86_64 to samba-4.11.2-13.el8.x86_64. 
According to Samba 4.11 WhatsNew the "SMB1 is disabled by default" now - and the HP printer unfortunately uses only SMB1. With the mentioned settings you enabled the SMB1 protocol again.


A 3d printable case for a ZigBee Gateway

I create a 3D model of a case for the ZigBee board.


In the cap is a cutout to place a neodymium magnet.

STL files are uploaded to my Thingivers account (link).


Using Cucumber with Gradle with tags

I want to run Cucumber from Gradle with the possibility to specify tags. Here is a build.gradle to do this:

  • gradle cucumber - will run all cucumber scenarios but not these tagged with @Ignore
  • gradle cucumber -P tags=@Smoketest - will run all smoketests but again will ignore these with the tag @Ignore.


TTN-Gateway in a box

During the last days I worked on the installation of my TTN-Gateway into a case. This is the result:

Beside the LoraWAN hardware I have installed an OLED display and 3 sensors (1x Si7021, 2x DS18B20). The OLED display is connected via I2C, the sensors via 1-wire and I2C.

The sensor data is read by Python3 Script and published with MQTT. The OLED is also controlled by a Python3 script. Both scripts run as systemd-service.

The software is available on github.

Little helper: mwc = more-without-comment

While configuring my linux nodes I found my alias mwc very helpful:

I used it to show the relevant (= uncommented and non-empty) lines in typical linux config files.


Raspi + RAK831 + converter board - make standard i2c bus available

The RAK831 converter board connects the standard i2c pins of the Raspi with the RAK831 board (RASPI.PIN3 -> RAK.PIN7, RASPI.PIN5 -> RAK.PIN9) (see picture). The RAK831 documentation states the line(s ?) are used to enable the RFSW1012 (see page 15) but does not uses it as i2c bus. The consequence is that the standard i2c bus cannot be used.

On the other hand when looking how to connect the RAK831 direct with a Raspi (e.g. here) the RAK pins 7 and 9 are not used.

This means the i2c bus can be revitalize by removing the 0R bridges R11 and R6 on the converter board.