4x6volt is 24v so yes to that question but the amount of amp hour capacity of the batteries is important too. It depends entirely on what you will be running. 920watts of solar coming in( based on you getting this maximum of course). The balancing trick is what you are using in a day(24hour period) and how low this will push your batteries. New batteries are the expensive part of a solar system and you don't want to be replacing them after a short amount of time. Whilst most of the literature about batteries is based on a 50% drain cycle ideally,if you really want to get your money's worth, you shouldn't be letting them drop below 80%. I am in my third year of second hand batteries and with careful stewardship they are still going strong. A little too much solar os key as an extra panel or two is cheaper than a new battery bank. My previous system was 24v with 800w of solar and I ran a very small house with a water pump but NO electric fridge freezer. Gas would be the way here.
So, a little too much solar and be slightly paranoid about the condition of your batteries. I would recommend a nice little battery monitor for this. They give you readings in/out in amps,volts,watts or to keep it really simple for the non techies a percentage of power left in batteries. You can see at a glance if you need to boost them with your geni then.
I don't know if you are building/installing yourself but I would recommend you make sure your system is upgradeable later. Eg your charge controller can handle more panels if you want them later.
I would also reccomend sizing your bank size carefully as you cannot"add" battery capacity later. Old batteries mixed with new pull them down to their operational level.
Bleh, that's enough for this time of the morning I think. I could put you in touch with someone who will go on about this stuff for hours if you really want to know. Ask me for an email address if you would like this.
Bruixot