Hi Glort
You're on the nail with the route I fancy taking, Charger, Battery, Inverter, you missed the last step - Lister!
I've had shiploads - pun intended! of experience with 12 volt boat stuff and know that most of the kit I (eventually!) plan on using is readily available, here's how I see it........
The barn has potable mains water, big step forward, it's the one thing that's bloody hard to make!
The nearest mains electric is 250m and €8000 away, for that sort of budget I can do a lot of playing.
I intend live more in the style of Bob (Ajaffa) and Starfire than feeding power hungry aircon and so on, as it will be a summer residence, at least for the start. so I'll fancy splitting the 12v system into 3.
300 amp hr battery for kitchen and hair dryer duty, with a 5000 w inverter, 150 ah battery for the 12v led lights and 150 ah battery for the 'media', tv, radio, internet ect. Both the small banks to have their own, smaller inverters.
The charging I'm happy to split, 8/12 hrs in the daytime for the kitchen, lights 6 / 8 hours or so in the evening, the rest to the media in the dark hours. all timer controlled to allow for balancing the charging time and add / subtract batteries as 'real time' usage dictates.
Anything left and it can go to hot water preheat.
When SHMBO dictates the need for 220v ac Lister should cover the washing machine, dishwasher,ect. and allow for power in the workshop. any left over 'Lister Power' to the battery banks and / or hot water preheat.
I've got a decent supply of WVO as well, having read most of your posts on the subject I never turn it down and ahve quite stash now, I'm storing more than my old tractor and Landrover are burning!
Wood burning stove, with back boiler, for cooking, domestic hot water, the rest to under floor heating, spring and autumn (we've good good quality beech for fuel up to the eyeballs) propane cooker and 'fridge freezer.
Having done the calc's to the best of my abillty I reckon 500w 24/7 is just about doable, 750 gives a little margin and 1000 will be Rolls Royce, should I be wrong I'll start the Lister early.
As it's all going to be modular any errors, increase or breakdowns can be covered from another part of the system, also, as you suggested I'm going to go with a large pipe to start with, which will help keep the pressure up at the the hydro plant and allow for more generation to be added without extra plumbing.
All I have to do is buy it, put in a road, re roof it, put in some windows and a concrete floor ans before I fit out the internals first!!
Cheers Stef