Three heating sources will be connected to a central thermal 360L store. The idea behind the store is that it should stay topped up with solar hot water through most of the year, and then provide enough stored heat for at least 2 days of overcast weather. Heating demands will be minimal in winter of course, since this is a passivhaus 
Thermal Store
360L thermal store from TiSun.
Solar Thermal
2.5 square meters of standard flat plate solar panel from TiSun.
Generator heat recovery
The cooling system on the generator could put out about 4kW of heat which will be recovered using a heat exchanger. The generator will be run for about 3 hours every 2 days, so that’s 6kWh per day which could raise the 500L store by 20 degrees (after the second day).
Wood Stove with backboiler
Will need 3kW of heat at the coldest time of the year to heat the entire house, this will mean a relatively small stove. I have the Morsoe Squirrel in mind, which outputs 4.6kW nominal and includes an optional 2.6kW boiler. But it doesn’t have an external air supply, so it will decrease the airtightness of the house.
The other option is the hunter herald 6, 7kW output total, 3kw for water heating and it supports an external intake, but it’s not as good looking as the Morsoe.
Gas boiler
The last fall back system will be the gas boiler plumbed into the Thermal store.
Radiant floor heating
For convenience we’ll include a radiant floor heating system if we’re too lazy to light the wood stove. To save on costs I plan to lay only half as much pipe, so with spacing double what it would normally be.