So my initial decision to spend the money on the D400s, panels and controllers may have not been so bad. The usage addition suggests they are sufficient to run the autopilot, electroinics ( including computer and SSB) frig, incendentials ( lights etc.) and still have a bit left over to charge the bank. I figured to run the genrator only when running AC or watermaker. Thought was to actively generate what was lost. ?In that setting was thnking of ~4kw genset. ?suggestions.
You will find that you run the generator more than you think, I suspect. This is especially true in south Florida where it is hot. 4kw is pretty low IMHO. I have owned two different generators, and going back, would not get anything smaller than 5kw. The Farryman on the Tayana is 5kw. This allows mom and dad to run the air conditioner, freezer (its a cold plate), and water heater. Anything beyond that starts really putting too heavy of a load on it.
Also, the best thing you can do for a generator is run it, the worst thing is let it set. I used to hardly run my generator at all, and it always seemed to be causing problems to the point I couldn't trust it. Since I started using it more regularly, it has been without problems.
1000 ah of batteries is a LOT of AH. Instead of that large of a battery bank (mine is 840), if I could go back, I would have spent more money upfront on more solar panels and less on batteries. Plus the cabelling for those batteries is a PITA to put in (nothing less than 0000, and probably 250 or 350). The truth is that most of your power loss will be during the day when it is hot (fridge) and you are running toasters or hair dryers or microwaves. Most of the night you will be asleep, and lights are no longer a major draw (assuming you are all LED). THe TV can be a draw at night, but realistically, you are looking at a few amps. So once you make it through the night, come daytime, you are back to making power and likely exceeding your needs with solar.
We have found the real killer for power was not air conditioning though. A nice breeze and good covers keeps the boat surprising cool (as a general rule, there are many exceptions). THe killer for us is hot water. The hot water heater draws 13 amps (110v), or 130+ inverted. I do not have a hot water dump for my solar. Going back, I would have put that in too. But it gives us an opportunity to run the generator or main while at hook. We often will run the main to heat the hot water on the boat. It seems to do it faster, though we sometimes will use the generator is the load on it is very small (like on the back end of charging the batts).