UNI-PVL128 used with Flexmax Outback

[sunbelt57]

I have (30) of the PVL128. I like the Outback Flexmax (60 or 80) amp. With the following specs:

Electrical Specifications
STC
(Standard Test Conditions)
(1000 W/m2, AM 1.5, 25 °C Cell Temperature)
Maximum Power (Pmax): 128 W
Voltage at Pmax (Vmp): 33.0 V
Current at Pmax (lmp): 3.88 A
Short-circuit Current (Isc): 4.8 A
Open-circuit Voltage (Voc): 47.6 V
Maximum Series Fuse Rating: 8 A

can I use the Flexmax in 24v mode? I measured the open voltage at 40v in full sunlight. The Flexmax doesn't recommend using solar panels in parellel. At 24v all 30 panels would produce ~150A. Should I use more than 1 Flexmax? Can someone recommend a cheaper controller? How many deep cycle batteries should I use at say ~100AH?

[Mary B]

You will need to run 2 strings into 2 parallel Flexmax 80's to stay within the charge controller limits. It can only deliver 80 amps to the battery max and if you run at 4 panels per series string at ~144 volts each string will be running ~4 amps.  You will them parallel 7 strings of 4 and that would be 28 amps @ 144 volts into the charge controller for 4,032 watts, at 24 volt into the batteries that wattage equals 168 amps which is way past the charge controller limits. I recommend downloading the charge controller manual and reading it.