Combining two measurements of the same thing

Hello,

I have two measurements of whole house energy consumption. One is provided by my energy supplier and is updated once a day in the early hours. It contains a 15 minute breakdown of energy consumed in the previous day and I regard this as my “gold-standard” for knowing what energy has been consumed by my household from the grid. But, as it’s delivered anywhere from 24 to 28 hours behind real-time, it’s not exactly ideal.

I have another measure of whole house energy consumption from a Lixee device attached to my eletricity meter which sends (over Zigbee) consumption measurements every minute. This is near real-time, but the measurements are frequently interrupted because the Lixee is on the very far reaches of my property and the closest I can put any Zigbee routers or coordinators is about 15 m away, behind a concrete wall, and the Lixee device is on the other side of the garden wall.

So, my problem is in two parts - one software, one hardware.

  1. How do I combine these two measurements of the same thing (energy consumption) into a single “sensor” that I can use in the Energy Dashboard without over counting the energy consumption.
    Can I have both in the Energy Dashboard, but then schedule a purging of the data from the Lixee device entities and their history when the better data arrives? Is a purge of data “before 00:00” possible? What other strategies can I try?
  2. How do I get more reliable communication from the Lixee. This is a long term project!

There’s no way to inject historical data into an entities history without hacking. I think I would put the must trustworthy one in the dashboard, even if it is late. Historical data is condenses anyway.

What you could do is use energy card plus and power card plus, combined with plotly or other advanced graphs with the more timely info on another dashboard for today, and the energy dashboard for long term.

Do you have a network connection near, or can you create one using powerline adapters? If so you can put an ethernet based coordinator closer by. If the real time sensor is trustworthy, question 1 might be less relevant.

I think your suggestion for the entities is my best option for now. I was hoping there was some kind of “fuzzy logic” I could employ to combine sensors, but I think my use case is pretty far from the usual!

Extending the network is really quite difficult. My meter is in my garden wall, on the street. There is obviously power there, but I’d need to add an actual consumer unit there in order to fit a powerline ethernet adaptor. I’ve already got a PoE ZigBee coordinator (an SLZB06M) as close as possible without putting it outside.
The Lixee device already has an antenna attached, so maybe I can extend that cable to bring the antenna closer to the coordinator.

I have the advantage of Solar PV with an inverter connected to a Modbus enabled power meter (which the inverter requires). I also have the benefit of (UK) Octopus Energy with Bottlecap Dave’s integration and the Octopus Mini (little device that pushes smart meter information up to Octopus and back via the Integration almost real time).

I therefore have yesterday’s half-hour consumption (after 09:00 each day) as a measure of what I will be charged for, an indication of the smart meter reading for today in half-hour consumption figures, and real-time grid power via Modbus and the inverter.

In general, I have a Riemann integral on the inverter provided power meter grid power to give grid energy (in and out) which I use on a power card with solar and load to show what is happening now. I use the Octopus Mini figures for graphs of ‘today’ as it progresses, I use the integration and my own API calls to collect yesterday (and older) energy figures for billing calculations, and I push the Riemann integral figures into the Energy Dashboard.

This, I believe, gives the best use of the data according to availability, reliability, and accuracy (particularly as the inverter provided power figures for a full day don’t agree with the historic smart meter readings by 5-10%).

In terms of hardware, the inverter is in the garage, the power meter is next to a mains power supply, and the meter connects via twisted pair to the inverter (Modbus comms over RS485) and via twisted pair round the house and through a couple of walls to the incoming meter box where there is a CT clamp. I am surprised that a CT clamp can work over this distance, but it does. With a power meter at at power point, and a long cable and CT clamp, you might be able to obtain reliable power readings over Modbus (even via a more reliable WiFi link to the meter).