Hi Dave, I will try to tell how I set up my system for 27 volts. I have the The SW 40/24 Xantrex inverter. It might function differently than yours. I also set my system up a couple of years ago and found that it was real confusing too. It takes care of itself now I haven't had to tweak it for a long time so I hope I don't say anything wrong. You will have to watch your system work threw every aspect and make sure that you don't have any problems like mentioned before, your dump tuning on when you are feeding grid power. I use charge control mode. In this mode first I had to calculate what amount of amps I could charge my battery with. If you have a small battery bank, which I think is the way to go, you don't want to be throwing 30 amps of charge at it in the bulk charge mode. I have four L - 16's so I think I set the inverter to 10 amps max charge at 120 volts. You don't want to boil your batteries hard! If for some reason you turn off your dc breaker than turn it back on you will need to reset this voltage. Next I set the float voltage to 26. 27 is normal for a 24 volt bank, but cut in is a tad earlier on my machine this way and I have more control, plus it leaves room for the voltages on the charge controllers. I set the bulk on the inverter to 28 ( I think it's been a while) When I turned on the inverter for the first time it ran a bulk charge. It will run a bulk charge every time you set it in charge mode if the voltage is below in my case 28 volts. I don't want my C- 40 to turn on while the inverter is in bulk, so I set the C - 40 to dump at 30 volts. I also have The C - 40 floating at 27 volts. Now when my inverter switches to float it will clamp the battery at 26 volts. I use a load that is slightly higher than what my wind turbine will produce on average. This way the inverter has to feed power to the battery every now and then to keep the voltage at 26. When the wind picks up the voltage will start to fluctuate between 26 and 30. when it hits 30 the C - 40 feeds power to a resister. It makes a buzzing noise then stops when the voltage goes below 30. In your case you would have another controller set to like 31, or you can go 29, and 30. What ever you will have to play with it so they are high enough that they don't turn on when your inverter is bulk charging. So, yours would hit say 29 volts first dump load would start buzzing. Its dumping power but not enough to clamp the voltage of the battery to 29 and the voltage goes up to 30. Then the second one kicks in and now they are both buzzing. The first one will not hit its max amps of dumping at 30 volts with the other controller dumping too. Then they will shut off in reverse order. I had my machine braked when ever I wasn't able to watch it for a long time till I could trust the system. I would turn it on preferably when the voltage is above 28 so it doesn't do a bulk charge and watch it go through the cycles. Now that I got my machine furling and have had confidence in my controls I leave her go at night and when I am at work except when a big storm is coming. Then I shut everything down and unplug the battery from the tower, and the bank. I pulled the furnaces off the grid in a way so I can plug them into an outlet feed by the R/E, or unplug them from there and plug them back into an outlet that goes back to the grid breaker. I hope this was helpful and I remembered what I did corectly . In all watch your system get to now it keep reading your manuals, tweak your system, and be safe. Than on the way have the fun, John.