How to make the most of WaterHeater:HeatPump heat output?

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I have a model which contains a WaterHeater:HeatPump which can provide 2,000 kWh per year from the DX coil. However this leaves the dwelling with unmet hours in the winter so it needs some extra heat input.

The way I see it, my options are to use an electric element in the WaterHeater:HeatPump itself, or to have a secondary tank which acts to supplement the output of the heat pump when required. My problem is that both of these approaches mean that the heat pump only provides around 1,000 kWh over the year, since even when heat is available from the heat pump, there is a good chance that the tank has already been heated by the element.

Is there any way around this, or is this just something I'll have to accept?