Comment Thermal storage to reduce peak load (Score 1) 215
I haven't seen any mention of adding a short term thermal storage unit to act as a buffer between the outside air heat pump and the inside heat exchanger. The system can then heat the thermal storage medium when it is most efficient to do so, and the inside heat exchanger can draw on that stored heat more continuously.
This thermal storage would be similar to a very short term geothermal system, with only a day or a week of storage, depending on the capacity.
This should be enough to reduce the need to resort to a backup heat system such as resistance heating.
The cost savings can be significant by smoothing the load and possibly taking advantage of times when electric power is cheaper.
There are not many thermal storage manufacturers, however.