Hello GizmoB…
I am right in the middle of figuring this all out. I have two Daikin HT units talking thru the RTD to my Arduino and I am now trying to figure out what to do with it all… : )
My goal is to try and squeeze a bit more efficiency out of my setup. Depending on how you read Daikin’s sketchy info, the efficiency goes down by as much as 30% between extremes of outside vs circulating temp, or ~13% in my setup.
I figure that the heat output from the emitters is determined by the temperature difference between emitter and house. House temp varies a bit, but not that much, so heat output and hence heat load to the Daikins is determined primarily by circulating temp.
So, I believe you can reduce circ temp and hence demand on your heat pumps to match PV output, but your system will then deliver less heat inside your home on a cloudy day. Slightly worried that this could be the wrong way round…
I do have in mind to crank up the circ temp just before the end of the night-time electricity rate, my thinking being that it will store more heat inside the house while I can get it at cheap rate, so reducing demand during daytime, which is similar-ish to your problem. That does involve giving the thermostats a nudge too, but that’s a separate project…
Do you have a buffer tank…? Seems like it would work well to crank the temp up inside your buffer when the sun is out, then draw on that heat in the shade…?
M