This is what I think also. A small, grid-independent PV array to run a heat pump mini split (combo AC/heater) combined with lots of thermal mass to hold the cold or heat. But it would very much depend on an individual home's architecture and layout.
I've been reducing my heating/cooling bills by adding forced return air to my home. By i ncreasing airflow over us as we sleep and go about activities, we are more comfortable at a setting 2-3 degrees warner than with insufficient airflow.
Our home was built with no return registers. All the AC and heat must return back to the central AC through gaps in the door sills (when the door is shut). We don't keep our bedroom door open so our cat won't wander out and roam the house. My utility reduction projects have been:
1. Improve airflow and comfort, allowing warmer AC settings to feel just as comfortable:
1a) Added a passive return register in master walk-in closet. DONE. It already allowed me to adjust temps up about 2 degrees and feel the same comfort level.
1b.) I'm installing an AC Infinity Airlift T12 programmable fan to the passive return register so that it always improves comfort, not just when the AC unit's fan is blowing
solar panel series and parallel calculator. Hoping I can bump up the temp 1 or 2 more degrees and get better comfort.
2.) Double the home's thermal mass/inertia so I can take advantage of cheaper (and more efficient) night time electric costs to heat/cool the home,
2a) Adding 750 liters of used wine bottles from our restaurant full of water under the stairs. This should almost double our home's thermal mass.
2b.) Add another AC Infinity Airlift fan on a timed cycle to store/capture the cheaper night time heat/cold and release it back to the home during peak cost hours (we get charged by time-of-use (TOU) and demand charges, as well as compound demand*TOU rates.
Edited: number of liters (typo).
