Need some suggestions...HVAC/heat pump, heat strips & solar

[mcdonsco]

I'm setting up an EcoFlow delta pro ultra system and Renogy panels (8kw array, starting with 2 ultras so 12kwh until we can see what the energy needs are after replacing our 38 year old heat pump that we definitely could not power with this system (nor our previous generator).

I've basically sized the system for once we have the heat pump replaced.

But, I've run into an issue with the heat strips needing 100amp service. We're likely going with the New Bosch inverter systems, specifically M18 or M20 3 ton. They're rated down to 5° & -4° respectively and in our area, we never get into single digits so technically we wouldn't use nor need the 15kw heat strips that these systems require (though we often used the ones in our old HP now as we had to when it got to freezing or below), but my understanding is, if these can operate down to those rates lows, we wouldn't need nor would never use the heat strips?

I've been talking to installers about maybe having the heat strips only on grid from our panel, then run everything else through the smart panel 2's (2 of them) / Ultra's and if/when the system wants to turn the strips on, it can and won't touch solar / battery power. But, will the rest of the system still work? If grid goes down (and thus strips are down) aside from blowing cold now and then for defrost, should the system still heat/work?

Basically, I have a bit of a cluster F and I'm not sure how to resolve this.

Any/all suggestions would be helpful. We haven't settled on an HVAC installer yet, for a few bids and now it seems like I may have to go with whoever can help me make this work?

 

[Solar Guppy]

In your climate with a modern heat pump there is no need for heat strips at all, just have the installers not connect and or not even install the heat strip in the air handler for your new system.

 

[manwithtalents]

You will need an inverter driven compressor heat pump along with a variable speed Airhandler. That combo will produce heat down to single digits and allow the supply air to become warmer ny adjusting indoor fan speed and both the DC compressor and ECM DC indoor fan motor, the efficiency ratings will be high , which is good in your case as it uses less power than conventional systems.You will get a few minutes of cold air during a defrost cycle. Knowing the heat loss of your structure is important in this case. Too small (BTU output) of a system and you'll be cold during the "close to freezing" periods. It is recommended, that when using a heat pump only for heat, to oversize it (if possible ). A quality HVAC Contractor will do a load calc to determine your heat loss/gain for proper sizing. That would also help you determine which contractor to use. Hope this helps, best of luck with your project.
Marty