I suppose it depends on how you spec the system. You could easily run a 2kw element of an inverter. Ideally you would want to do this through a changeover just for those emergency situations.
You do get Daikin VRV systems that are able to do this. They don’t come cheap though.
Once again I am in need some education (Sigh - Again) Could you point me to what a Temperature bypass valve looks like and where I can read about it, please. Without being “banned” for helping a Noob on such things
8.7kW Heat Pump (teal on bottom graph) on 800l tank with 3kW element kicking in (red on bottom graph) when excess solar PV available - controlled using Home Assistant + Node Red automation. Top graph is temps in bottom, mid and top of tank. All water heating take place between 10:00 and 16:00. Ring Main distributes to ‘points of use’ far from tank on demand only - RF button press or smart phone app.
Agree - heat pump draws at port 20% from bottom and returns at 40% from bottom. Setup not done with tempering/loading valve - not worried about HP return short circuiting to outlet and more efficient without - so heat pumps draws water at 20% level temp, adds approx. 5degC and returns water to 40% level in tank.