As others have already said, you need a Kwh meter, and take some measurements right through both mid summer and mid winter. Only then can you sensibly size your system. Reviewing your previous power bills over the last few years might be a goods starting point if you are on grid at the moment.
But its useless saying I have this and that.
For example, a simple electric wall clock draws ten watts and runs 24 hours per day. That is 240 watt hours every day.
An electric Kettle takes two minutes to boil, draws 2.4Kw and I use it ten times per day, mostly for coffee.
2400 watts x 2 x 10 = 48Kw minutes divide by 60 its only 800 watt hours.
You would think the clock is nothing, and the kettle a real power hog, but its only 3.3 times as power hungry as the clock each day.
If you do some data logging you will find the most wasteful things are the small loads that run 24 hours. The biggest loads might be run for only minutes at a time, microwave oven for example.
I was shocked to discover my washing machine used as much power each day turned off as running a single full load of washing.
Armed with information like this you can make some very simple decisions.
Put the wall clock into the trash, and buy a battery wall clock that runs for a whole year on a single AA battery.
In my case, unplug the damned washing machine unless its actually being used.
Many other discoveries like dumping my old refrigerator and buying a more modern energy efficient unit that uses one third of the power.
I managed to HALVE my total daily power consumption without any change to lifestyle or comfort.
A very big difference between spensing say $4K on a battery, and having to buy an $8K battery and twice as many panels to charge it.
