I installed a 1.02KW PV system at my house this fall.It consists of (6) 170W, 24V Sharp panels, (6) 100Ah AGM Deep cycle batteries, 3000W inverter, transfer switch, six space alternative energy panel etc.
With the use of this battery monitor I was able to program the charge controller to disconnect and reconnect the inverter so the batteries would not discharge below 50%. Voltage readings are way off when charging or when under a load. I also like seeing how many amps are going in or out of the battery bank. It tell you a lot of other stuff too.
Now I know that the batteries are being maintained properly and it is no longer a mystery as to what the magic number is for that transfer switch to automatically go to house power.
Have fun, I am