Solar controllers do not have weatherproofing, so they are best installed indoors. Find a safe place if you have to install the controller outdoors. There should be a roof over it in case of a downpour. Place the controller on a piece of wood, PVC or any non-conductive material. Do not. If your gel battery already has cables, skip to the next step. Otherwise, connect the wires into the battery. The cables are usually red (positive) and black (negative). Important: connect the battery to the charge controller before you plug the battery into the solar panel.if you connect the battery to the solar panel first, this could. Take the cables running from the solar controllers and put male and female MC4 connectors on them. You need to install the connectors so you can plug these into.