One thing that hasn't been mentioned: Unless your controller has remote battery voltage sense, it is imperative that the controller be located as close to the battery terminals as possible, and I don't mean 15 or 20 feet. At 20 amps I have almost a full volt drop between the output of the controller and the batteries. This means that the controller starts to taper off the amps thinking the batteries are at 14.6V when they are in fact only 13.8V. If you don't know already (you will soon learn in your reading) batteries need to get up to 14.4 volts for a while to become fully charged. I unknowingly spent an entire season undercharging my batteries and couldn't figure out why. :S