A/C at sea?
That is a LOT of power that needs to be generated. How much? Depends on the A/C unit.
Your best to do a power usage plan for whatever electrical/electronic units you hope to use, and then decide how big a solar
panel/battery/generator/wind mill combination will be required to drive all of that. You may find you want to cut back on some things. If your hoping to do longer passages, your going to need all the room for supplies and tankage that you can get, and a large generator
will interfere with that.
And full blown internet
? That requires a big budget
. Where are you going to be sailing? In most places wifi
or cell coverage is at least adequate.
To give you some idea, if you haven't researched it yet, take a look at the costs, speed and small amount of data allowed.
Inmarsat BGAN Satellite Service Plans - GlobalCom
I think you will find that you will be doing a wants versus needs analysis, as you depending where you plan on sailing, your going to meet either space constraints or dollar ones.