12 volt or 24 volt

Re: 12 volt or 24 volt

either voltage would work, but it is usually better to have the batteries wired in series to help preserve battery balance better. as far as how long the load will operate for is a problem for you if it is much longer than about an hour or so. 2 12v batteries at 100ah is 2400wh total power of which you should realize that 600w is a significant amount of that as it is a c/4 rate reducing available to about 80% of the original 2400wh giving you 1960wh. furthermore, you should not take out more than 50% of your capacity bringing it down to 980wh useable. with a 600w load this is a bit more than 1.6hrs if the voltage doesn't drop out the inverter by going too low first.

so if you went with 1.6hrs at 600w fror the 980wh total you will need this plus another 23% for efficiency losses at the pvs' top ratings or 1273w at the stc ratings minimum and if that is over say 5 good hours of full sun it would be 255w so you're good there with 450w stc. it also works out alright with the charge % as 150w stc (2 in series) / 18v = 8 .33 x 3 strings = 25a x .77 (efficiency) = 19.25ah. 19.25a / 100ah = 19.25% if i figured this right. (tired.) guys will correct me if i goofed in my math, but it is certainly ok as far as i can tell. for an fla this is a high charge rate so be prepared for higher maintenance.