Solar panels must be connected to a battery of the same voltage.
In order to connect a solar panel to a battery, you must first ensure that the panel and the battery have the same voltage. Of course, this is a lot easier if the panel and battery are compatible right off the shelf, but there is also an easy way to change the voltage of your battery system and make it compatible with the panel. In the case of a 24V panel and a 12V battery, you can connect the two by connecting your battery to another battery with a series connection. Does this Spark an idea?
1. Connect the negative end (terminal) of one 12V battery to the positive end (terminal) of the second 12V battery using a battery cable.
You are connecting the batteries in a series, a process which doubles the voltage while keeping the capacity (amps hours) the same. If you connect the batteries in parallel (positive to positive and negative to negative), you will double the capacity, but keep the voltage constant.
2. Connect a second battery cable to the positive terminal on the first battery.
3. Connect a third battery cable to the negative terminal on the second battery.
4. Connect the two loose cables to the appropriate negative and positive inputs in your solar panel or any other input device.
Most solar panel installation specialists recommend putting a charge controller between your batteries and the panel in order to protect both your panels and your batteries from changes in the flow of energy as the amount of sunlight and the power generation of your panels changes. If you choose to use a charge controller, connect the batteries to your charge controller and your charge controller to the solar panels.