Eh, that's a bit difficult to answer... if your power generation exceeds your power consumption, yes, of course - assuming that you have proper load management/charging controls and so forth. Go from the other direction: What do you need power for? How many kw-hrs/day? What does it take at the low voltage DC side for your inverter to meet those demands? And so forth.

Not economical to cobble up photovoltaic on your own and any significant amount of power from them is not going to be inexpensive. Then there's nighttime, your latitude, and your maritime climate to factor in... I'm guessing that PV costs would be frightening and battery storage requirements significantly larger than a sunnier clime.

But you should have plenty of wind and to a certain extent it is feasible to DIY some or possibly all of a wind generating system - proper controls would be simpler to purchase, but the generation can be handled on a "Junkyard Wars" approach up to about 360w to ~ 1.5kw at max output, depending on your alternator - be forewarned; the size of the mechanical parts that the wind operates on are probably much larger than you think.

I'm not at all opposed to the idea; good for you. Just trying to introduce a little reality. Converting lowgrade energy (sunlight or wind) into high grade energy takes up a bit of space and initial cash outlay.

You could tinker a bit with a surplus automobile alternator, a surplus 1 lung gasoline engine (over here we would think of something like a used 5hp lawnmower engine), appropriate pulleys and belt, and whatever automotive gizzards you need to rectify (if you're using an old externally rectified alternator) and regulate the voltage. Usually you'll find internal rectification, but I'm not sure anymore about voltage regulators - I know what had them and what they look like, but nowadays... you'll have to ask.

You'll need your battery to provide field current for the alternator (there are a FEW that are self-exciting, but not many). Just hook it all up electrically as if it was in the vehicle. A careful and clever person could easily use the lawnmower deck to mount the alternator and battery and inverter along with the engine... I imagine the alternator bearings might not like the vertical mounting forever, but who knows <shrug>

While you're gathering experience and data from that, you could do a bit of reading on extracting power from the wind - the mechanical part. Then decide if you want to go ahead. All in all, I think it would be a fascinating opportunity for you to learn about how all those bits go together and at worst case you'll have a junkyard wars sort of portable generator that has a battery reservoir - drive the neighbors mad wondering what you'll cook up next, hehehe...

I've done the alternator-engine-vr thing many years ago - it works. TANSTAAFL. Do the math on the DC side and you'll see: Suppose a 55 amp alternator @ nominal 12v - that's 660watts. Is that enough? Bigger ampacity alternator... hmmm, let's say 135 amp (less common in what you're looking for, but available). Now you've theoretically got 1620 watts. And I'll predict that a 5hp nominal engine will have all it wants cranking that many amps out of an alternator, even though in theory it is capable of more. You'll want some airflow thru the alternator and over the engine if you're running either at close to max - but these are all fun things to figure out, so I'll demure. Watch your wire sizes on the low voltage side - those are big currents and require big wires - especially if your paradigm is at over 200v AC.

It's possible to make the whole thing amazing quiet, FWIW, although forced (and baffled for noise control) air for cooling becomes essential then, as well as re-locating the fuel tank.

Heck, I've just talked myself into a "Science Dad" project with the boys! Last time I did this sort of thing, they hadn't been born yet...

Hope you take a crack at it and have fun learning the answers to your questions.

Regards,

Tom