Matching your Air Conditioning to Excess Solar.
Again for those long days of negative feed in, matching your air conditioning to consume your excess solar is an excellent sink for all that very cheap energy. Your household stays cool, bonus if you work from home, have pets and it also saves having to blast the aircon in the afternoon when the prices are high.
There is a great project which uses the DRED interface on most aircon systems to limit power consumption using a set of four relays: Controlling Air conditioner using Demand Enabled Response Device per AS/NZS 4755
My premise was to change the setpoint to keep the aircon in the ball park of my excess solar consumption. If I’m drawing too much power, I raise the set point, and the aircon draws less power. if I’m generating too much excess solar I reduce the set point and the aircon draws more power.
To calculate the relevant set point automation I am using the following formula:
SetPoint = ExternalTemp - CoolingFactor/ExcessSolarPower
I was also playing around with InternalTemp as a variable, but that doesn’t seem to have much impact on the long term power consumption.
The CoolingFactor is in (W / °C) and is different for every household, depends on how big your AC is, how good is your insulation and thermal mass. For my household I find a cooling factor of 1500 W / °C works pretty well. I set up the CoolingFactor as an input_number helper.
I use a template calculate the helper to actual excess solar power available for HVAC.
Finally, I have an automation which is triggered when the excess solar power changes to change the setpoint of my air conditioner, in this automation you can see I also moderate the power by the battery state of charge, so my battery fills first and then in the afternoon once the battery is full, the aircon gets the bulk of the power to drive down the house temp.
Interested to hear how others are managing their aircon with HA and Amber low prices.
