ᐅ Combine an air-to-water heat pump with a wood-burning stove connected to the central heating system

Hello everyone,

We are currently planning a single-family home built with solid construction to KFW55 standard.
Two full stories, partially basement, without basement about 230m² (2,475 sq ft) of living space for 5 people.
The location is southern Germany at 550m (1,804 ft) above sea level. The shell construction planning is fixed, and the shell and gable roof have already been contracted. Construction start is week 22/2020.
I have also already contracted a 23kWp photovoltaic system on the south/west roof of the house and the south/east roof of the garage.
Due to economic reasons, a battery storage system is currently not an option.
The heating load according to calculation is about 5.5 kW at -15°C (5°F) ambient temperature.

Now it’s time to plan the heating system:
Current status is:

• Underfloor heating in all rooms except for the pantry and storage/technical room in the basement.
• Central ventilation system combined with an air-to-water heat pump. Air-to-water heat pump installed indoors in the basement.
• A hydronic wood-burning stove from Hoxter with firing from a separate room, i.e., no wood/dirt in the living room. I still have 30rm (cords) of beech wood stored free of charge.
• Due to the high capacity of the photovoltaic system and the stove, I see no sense in a trench collector.
• An 800-liter (210-gallon) buffer tank can be placed almost directly under the Hoxter stove in the basement. The distance to the air-to-water heat pump is about 2.5m (8 feet).

Now I have the first offer for a Stiebel Eltron LWZ 8 cs Premium.
Am I correct to assume that under the above parameters the LWZ 5 cs would also be sufficient?

How can I best integrate the Hoxter stove into the heating system?

As a layperson, I currently see two options:
Option 1
An 800-liter (210-gallon) buffer tank only for heating operation, without domestic hot water.
Domestic hot water is generated by the air-to-water heat pump during daylight; the heat pump runs mainly during the day and stores heat in the screed. From 4 p.m. onward, the Hoxter stove is fired.
The heating circuit would then have to switch to the buffer tank when a certain temperature X is reached in the stove circuit or the heat pump buffer.

Option 2
The air-to-water heat pump always charges the buffer tank with a maximum flow temperature of about 40°C (104°F). If this temperature is exceeded by the stove operation, the heat pump switches off. Also, the heat pump would be programmed to operate only during daytime.
I understand that the combination of air-to-water heat pump with a buffer tank is suboptimal. But a stove without hydronic integration also makes no sense, as it would quickly overheat.

My current bidder is almost unreachable for technical evaluation at the moment, fully booked, so I have no real information about integrating the stove yet.
What do you suggest?
Which other air-to-water heat pump manufacturers would you consider for this configuration?

Thank you very much,
GSGaucho