If you go with a 12 volt battery bank and two or three panels at a time wired in series, you will be able to take better much advantage of low light conditions. That is a big plus IMO.
Inverters are made to connect to 12 or 24 volt; just make sure you get the right one. You can then have 110 volt.
To get 12 volt from a 24 volt battery bank, you would need a step down transformer Like 29chico said. They are very efficient, but that is one more item you need. Strictly going by the stated max watts pv input rating, max amps rating, and the max volt rating of the 40 amp MPPT controller, no matter how you wire it, you will need a transformer, or another controller, or ditch the smaller one and get a really big controller.
If you wire them all in series, it won't work. The controller can handle a max of 100 volts (which is good), but 6 panels wired in series is 117.48 volts (17.8 volts Vmp * 6 panels * 110% leeway) which is too much.
If you wire them all in parallel, it won't work. The controller can handle 40 amps (which is good), but if you wired all 6 parallel, you would get 42.15 amps (5.62 amp Imp * 6 panels * 125% leeway) which is too much.
If you do a combination of series and parallel, it would work with a 24 volt battery bank, but not a 12 volt bank. If you wired two strings of three panels each you would get 58.74 volts Vmp which is well within the max 100 volts. Then if you wired those two strings parallel, you would get 16.86 amps Imp which is well within the 40 amp rating.
You could also go with 2 panels in series and the 3 strings wired in parallel on a 24 volt bank, but not on a 12 volt bank with only one controller.
You could go with 4 panels in series then 2 panels in series, but then you would need a separate, smaller controller for the small 2 panel array.
The only thing holding you back from using a 12 volt bank with this series/parallel setup is the 400 watt maximum input pv rating. Since the 24 volt rating is good for 800 watts worth of panels, then the 600 watts of panels you have would work for a 24 volt bank. But now you need to buy a transformer.
If you went with two controllers and no transformer wired to a 12 volt battery bank and one controller failed, you would still get solar from the remaining 3 panels. This redundancy is nice to have. Since there is no transformer to fail, you would always be able to power your 12 volt lighting and appliances as long as your batteries have juice. This is my favorite option.
If you went with one controller and one transformer on a 24 volt bank and the one controller failed, you wouldn't be getting any solar from any of the 6 panels. If the transformer failed, you would lose all of your 12 volt DC lighting and appliances. This is my least favorite option.
I'm not sure that the rating of 400 watts maximum for a 12 volt battery bank is a real consideration. As long as the Vmp and the Imp is good, that may be all you need. I would call Renogy and see if the max pv input of 400 watts at 12 volts is something to seriously consider. Unless someone here knows the answer.
Unless you have long lengths of wire (about 20 to 30 feet and more), 12 volt really is ideal. 12 volt is very suitable for short distances of wire. If you can stay less than 12 feet (or close to it), your losses from resistance minimal.
All of those 100 watt panels is going to take a lot of wiring and a lot of mounting. Much easier to wire and mount two large 300+ watt panels.
I just purchased two 60 cell, 285 watt solar panels. No UPS here.- they have to be palletized and freighted in on a semi truck. That is about $150 shipping fee. You have to pick them up at a terminal. Freight is getting more and more expensive. At least you are getting a much, much better delivery service.
You may also have to pay a "break pallet" fee. When you order two panels, if each pallet has 20 solar panels on it, and they need to open one up to get those two panels out, they charge you for that. If they are ethical and have already charged someone that fee, they may wave that fee. Don't hold your breath.
