Solar export auto consumption


Im new to solar and to home assistant but enjoying learing a few nice dashboards or automations. Ive also installed Node Red to simplify things hopefully

Im using a Shelly EM to monitor the grid and the solar production. Unfortunatly my Solis inverter is not easily supported by HA so i was ok with using Shelly EM.

Ideally i would like to have a solar divrter which monitors any excess solar >100w and then gives any excess to a 3KW immersion heater. Until i get that i would like to use a script or automation to turn on some devices in the house. Ive a combination of Shelly PM, Sonoff and TP Link devices and am mainly thinking of turning on fans, heaters etc.

I would document the power consumption in watts of the device to know which to turn on. My theroy would be;

if ‘export to grid’ > 100w then turn on 'Device1(90W)
if ‘export to grid’ > 800w then turn on 'Device1(800W)

I cant find a recent example of someone building this but i think Node red would be easiest right? i think stepping up woudl work for turning devices on but then have a switch at the start to say if ‘export to grid’ <= 0 then turn devices off and wait 2 mins (to stop fast cycling of the appliance.

What do people think? to me it seems like anyone with HA and solar would be doing something like this but im not sure how to start and to start in NodeRed or HA script.


This is pretty much what I’m looking to do. I want to turn on an immersion heater if I am exporting. I know there are off the shelf systems that can do this, but it shouldn’t be too hard to rig this up using a simple immersion and a controllable plug. My only concern is not using too much power, so I am only using what is extra to heat the water. I guess this smarts is what you are paying for with iboost systems.