There is a ratio of solar panel to capacity that's required to keep them fully charged. I run roughly 2x panel capacity to battery size because the panel will only produce full power with proper incident light which only happens if you track the sun and if it's above the horizon enough. In the winter I might get a couple of hours of full charging from my panel (which have historically just been roof mounted at home), which is a 24V panel to-boot. In the summer it's a lot better, the battery stays topped a lot better.
Those batteries Marco has are probably perfect being SLABs. If you need to condition them I can do that, although I doubt they do.
Generators get the same multiplier as mains powered stations, so I do guess it is too easy. OTOH it's sure a lot easier to run your house fridge during longer power outages...
'91 Toyota Pickup
'09 Kawasaki KLR650
'12 Gunnar Rockhound 29
"They say the test of literary power is whether a man can write an inscription. I say, 'Can he name a kitten?'" -- Samuel Butler