Smart water heating PV excess energy

Configuration
1

Hi all!

I am rather new to automation and can’t seem to figure out how to do the following:
I have a HomeWizard P1 energy meter placed, which monitors power consumption.
Solar panels are installed and I have a variable energy contract with prices changing every hour.
When the solar panels produce more than I consume (see image), the power will be exported to the grid and billed within the hour. At this time, the energy price is very low, because there is a lot of solar energy at those times.

HWEnergy-Snapshot
HWEnergy-Snapshot1920×1080 160 KB

Therefor I would like to have an automated system that toggles a Wifi switch to activate a water heater that heats up a 300 L buffer tank for domestic water (3.000 watt - more than the solar panels should generate). I made a small script myself to get an idea (not working, just a concept):


execute = function(wifi switch ON)

at (whole hour xx:00) check consumption.today (P1 meter)
every minute check consumption.currenttotal;
loop()
if (consumption.today > consumption.currenttotal) switch heater on 
if (consumption.today < consumption.currenttotal) switch heater off
delay(60 seconds)
if (consumption.today > consumption.currenttotal) switch heater on
if (consumption.today < consumption.currenttotal) switch heater off

What I would like to do is read the powercounter at every whole hour as a starting point, and then use the water heater to consume energy as long as the consumption is lower than the starting value. I need to do this every hour, since the eletric company charges me for every hour of consumption.

Is there anyone who could help me creating a script for this? I think it is not that comlicated, but I am not able to figure it out myself.

Thanks a million!

2

Can’t you just try this with basic automations? It is a powerful tool that allows exactly what you want and you get excellent debugging tools if it does not work as expected.

3

What do you mean? Do you have an example?

4
5

No clou on what to do with the P1 reading, it is live; i need to store values first and then compare. Could you help me on how to do so?

6

Add the P1 meter in configuration.

Then all data is stored in the database. You can automate based on the ‘active power’. Start to make a simple automation like ‘turn on a light when power goes below zero’. Extend this until you have what you need.

There are quite a few topics about automations. And you can ask about the HomeWizard integration here: HomeWizard Energy (Wifi P1 meter, kWh meter and Energy Socket)