To further ...
Plan is to install a heat pump of about 16-20 kW, air-water, as they can have an efficiency in the 5.8 COP level.
This means you get 5.8 times the heat vs the power you put in.
So a 4 kW max electrical load delivers upto 20 kW of heating / cooling.
I will keep the current oil heating system, but simply not use.
The oil bill last year was 3000 , which will drop to essentially zero.
As an extra, I will get air-con throughout the very large 400m2 house and shop.
Estimated cost is around 8-10k, for 14 fan-coil units (replace radiators).
Plus about 800 in work hours.
Iīm a contractor and these are my own import materials costs.
A commercial air-conditioning install of 20 kW would cost over 20 k (10-12 splits, give or take).
And because of the PV array, heating and aircon will be free, for now (30 years).
Saving about 3500 in electric bills, and 3000 in heating bills, per year.
And a 1000 per year subsidy from the gov. for 4 years.