How to Set Up a Solar Charge Controller for a Battery Bank

Solar Panel Sizing and Wiring

The Solar panels may come with MC4 connectors. Don’t cut these connectors as it may void the warranty.  Rather buy two extension cables with bear sides and one with male and female connectors. Use the bear side to connect directly to the controller.

To connect multiple solar panels in series join the Positive to negative terminal or in parallel positive to positive. There should be one positive and one negative terminal at the end of the array to connect to the solar panels.

Note that when using Parallel wiring the amperage from every solar panel is added and this gives the amperage of the system. Make sure that this does not go beyond the rated amps of the controller. In a Series connection, the current is divided by the total number of panels while the voltage is added up. Again the Voltage should not go beyond the rated voltage of the controller.

If you want to add more solar panels than the rated amps on the controller, you can add another controller and parallel it to the first controller.

Battery Voltage

While the first step in the process is connecting the battery to the controller. This is after you ensure that the battery voltage is higher than 6V for a 12V system and 18V for a 24V system. Otherwise, the controller can detect the battery voltage.

The controller should have a system voltage recognition mechanism to recognize whether it’s a 12V or 24V system. This is determined by how you wire your batteries. Battery systems can go up to 36V and 48V. Ensure your controller can support the system setup.

You may still need to set battery type (whether Sealed, Flooded, or Gel) and capacity in amp-hours. There are also options for user-defined settings and parameters that you can change to suit your batteries. This is especially important if you are using lithium batteries.

Load

You will find a load option on the terminal of a solar controller. This is not just for any load but must be a DC power device with the same working voltage as the rated voltage of the battery. Do not connect an inverter to the load terminal as the inverters have surges that might blow the controller.

Some controllers have 5V output for small loads like lights and light chargers.

Wire

Under sizing the wiring is a really bad mistake to make while they may be drops in voltage because of bigger wire better safe than sorry. Do not use a 10 AWG wire on 30 amp controller or system for that matter.  30 amps will warm up the wires and you would need something around 6 AWG.

LED Indicators

The LED indicators can help detect errors in the system and if there’s any short-circuiting in the system it will flash to indicate. If the system is working it will show the charging status. Some controllers have two separate indicators for the PV and for the battery. Reference the controller’s manual to see what the colors of the indicators mean. Different controllers use different colors to indicate errors if the system isn’t working.

Mounting

A controller may have 20-40 amps of current flowing through it at any given time. This produces a great deal of heat. This heat must be dissipated other the charge controller will fail. This is why it is recommended to choose a controller with a good heat sink. Also, ensure to mount the controller where there is good ventilation.

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