Which heating system to choose when replacing the heater after 36 years?

Hello, our new property currently has an oil heating system installed. It needs to be replaced when we move in.

It is a bungalow with 112 sqm. The heating room is in the basement. Next to it is the 4000-liter welded oil tank. The house has a two-flue chimney. The previous owners also had a pellet stove in the living room that was used additionally.

Now I am considering which type of heating I should choose. A gas connection is not possible because there is no gas line.

My idea was to replace the oil boiler in the basement and additionally install either a water-bearing pellet or wood stove in the living room.
Possibly solar in the next few years. (I am not sure about that yet because I have often read that it brings little benefit.)

What would you install? Does it make sense to use a water-bearing stove in addition to the oil heating? Or just a simple wood stove for occasional use?

What are your heating costs per year? How high is the heat loss of the house? It is difficult to say in general... but often it makes sense – if the tank is still in good condition – to only replace the heating system and avoid any experiments.

Ok. I haven’t lived inside myself yet, I only know from the previous owner that he apparently used about 1000 liters of heating oil and heated the rest with a pellet stove. The pellet stove is 10kw. Unfortunately, I don’t know more.

That would be 50 € heating per month... either the house is relatively well insulated, or the stove was in use a lot. With the "low" consumption, a modern oil heating system is probably the most suitable option.

I doubt that the house is well insulated, built in 1980, with premium facade panels on the outside. No full thermal insulation. Consumption according to the energy certificate is 30000 kWh heating oil with hot water and 25000 kWh pellet. So he probably heated 50/50.

My consideration was whether I should use a normal wood or pellet stove in addition to the oil heating, or a water-carrying one.

1. Modern oil boiler. 2. Insulate the house ([consult an energy advisor] to determine which measures are sensible). 3. If desired, an additional stove/fireplace in the living area for comfort. Is the ceiling or the roof insulated?