How to: Use actual grid voltage for Power usage, Energy consumption, and Coefficient of Performance (COP) calculations
Power usage, Energy consumption, and Coefficient of Performance (COP) are based on data from an internal current sensor. These values require additional information—such as grid voltage—which isn’t measured by your Daikin Altherma. By default, the app assumes a grid voltage of 230V for these calculations.
This post will show you how to configure the Daikin Altherma app to read your actual voltage(s) from your MQTT broker, and how you can send the actual voltage(s) to your MQTT broker in case the information is not yet available on your broker.
Configuring the Daikin Altherma app in Homey
Open the Homey app and go to the Daikin Altherma app’s setting. Now scroll past the MQTT information to reach the Use external voltage setting in the Power calculation section.
Slide the slider to the right to turn the feature on and reveal the MQTT topics for phase voltages
As you can see, the topics will default to espaltherma/grid/voltage1, espaltherma/grid/voltage2 and espaltherma/grid/voltage3. You can choose your own topics if you want, but the must be available in the espaltherma topic.
When you don’t have a 3-phase system, please publish your voltage to 1 topic, but enter it on all 3 lines.
When you’re satisfied with the topics, press Save to store them and Done to leave the app’s settings. The app will immediately start using the values that are published, as long as they are within the 207-253 Volt range.
Sending grid voltages from Homey to your MQTT broker
To publish your grid voltages to your MQTT broker (when they’re available in Homey—for example via the Homey Energy Dongle), you first need an app that can send data to an MQTT broker. If you don’t have one installed yet, go to the Homey App Store and install MQTT Client by @scanno.
After setting that up, create a Flow to send the grid voltage data to your MQTT broker. See the example below for how to do this:
That’s it! Every 30 seconds the voltage information will be written to the MQTT broker and the Daikin Altherma app will use them to do the Power Usage and Energy Consumption calculations.
