Share 'Borrowing from solar thermal system - Why not use two tank systems with heat pump water heaters?'

We are starting to roll out heat pump water heaters in the Pacific Northwest (Oregon, Washington, Idaho, Montana, and Wyoming).  One of the concerns we have in colder climates is the recovery time when the ambient air is cold. The lower the ambient temperature the less effective the heat pump water heater will be in generating hot water causing issues in households with more people, more bathroom…