It seems you took my comment as an attack on heat pumps, which I certainly didn't intend! Such is life in our needlessly polarized information environment. Thank you for the description of your system though! I've got thoughts of a heat pump in my future, and I will be well involved in the design if I don't outright DIY, so it's nice to hear about other people's setups.
By "lose 25% of its capacity", I mean because with curtailment it could be off up to 25% of the time (assuming the same curtailment schedule as summer). The focus on "coldest days" is because that is when your house needs the most heat (regardless of source type). Based on the climate, I assume your heat pump was sized based on the minimum it needs to supply for heating loads on the "design day" (coldest day generally expected for your climate), meaning on the coldest days it requires most of its capacity to keep the house temperature steady. Whereas it's oversized for summer so it can still keep up even if it loses a bunch of capacity due to curtailment.
I'm a bit surprised with a solid backup heat source that winter curtailment isn't more attractive to you (it would also help exercise your backup heat). Does it really not make financial sense? Or is it more of an idealistic thing of not wanting to burn oil/gas as much as possible?
By "lose 25% of its capacity", I mean because with curtailment it could be off up to 25% of the time (assuming the same curtailment schedule as summer). The focus on "coldest days" is because that is when your house needs the most heat (regardless of source type). Based on the climate, I assume your heat pump was sized based on the minimum it needs to supply for heating loads on the "design day" (coldest day generally expected for your climate), meaning on the coldest days it requires most of its capacity to keep the house temperature steady. Whereas it's oversized for summer so it can still keep up even if it loses a bunch of capacity due to curtailment.
I'm a bit surprised with a solid backup heat source that winter curtailment isn't more attractive to you (it would also help exercise your backup heat). Does it really not make financial sense? Or is it more of an idealistic thing of not wanting to burn oil/gas as much as possible?