Where to start

The order matters more than the choice: insulate, then heat, then produce.

The right order of works

1
Insulate first
Heating a leaky house means paying to warm the outdoors. The roof comes first: that is where the heat goes.
2
Replace the heating next
A heat pump fitted to a poorly insulated building uses more than expected and disappoints. Insulated, it keeps its promises.
3
Produce last
Panels are sized on the consumption that remains after the first two steps, never on the figure from before the works.

Central inverter or micro-inverters, mounting suited to tiles, slate or a flat roof.

Lithium battery with a warranty in cycles, sized on your evening profile.

Heat-loss calculation, choice of emitters and a check on the noise level towards the neighbours.

Between the rafters or from the outside, with a vapour barrier and ventilation of the under-roof.

Heat-pump water heater or coupling to the heat pump, according to the size of the household.

A costed survey of the building, with the items ranked by return on each euro invested.

Often yes. Due south produces more at midday, east-west spreads the output across the day, which suits a household that is out at noon.