Confirm outage operation
Ask the solar and battery provider whether the system is configured to supply power during a grid outage and which circuits it supports. DOE explains that ordinary solar systems generally shut down when grid power fails; independent operation needs suitable inverter and storage equipment. DOE solar resilience guidance.
Do not assume a battery shown in an app backs up the heat pump. Have the provider verify outdoor-unit, indoor-unit, control, and backup-heat circuits.
Separate power from duration
Power, measured in kilowatts, is how much the battery can supply at a time. Stored energy, measured in kilowatt-hours, is what is available over time. Both matter. DOE storage basics.
The HVAC provider supplies the system's requirements. The electrical or battery provider evaluates startup, running demand, other loads, usable stored energy, reserve settings, and permitted modes.
Ask for a cold-weather duration estimate that includes backup heat and realistic recharge assumptions. Overnight operation and several cloudy or snowy days are different scenarios from a sunny afternoon.
Define the household need
Identify priority rooms, occupants' needs, and the outage length you want to prepare for. Ask whether approved load management changes available heating duration.
Do not disable protective controls or disconnect backup heat yourself to stretch a battery. Operating limits need qualified assessment of heating, equipment, and property protection.
Request the estimate's assumptions and conditions that would shorten it. A calculation is not a promise that every outage will be covered.
Your next step is a coordinated HVAC and electrical review before the conversion is finalized. If adequate heat cannot be supported, identify another heated place and when the household will move there. That makes solar and storage part of a usable plan rather than an assumed safety net.