Do you Need to Use the Load Output Terminals on a Solar Charge Controller? (+ What Appliances to Connect)

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Got a new solar charge controller with two terminals for the load connections and wondering whether you have to use it or if there is no power output, what you can do to fix it?

Or, perhaps you have a controller without load output terminals and are wondering if this is an issue?

In this post, I cover whether you have to use the load output terminal of the solar charge controller, how to use them safely to avoid damage to your appliance and controller, what to do if your controller has no load output terminals, and what you can do in case there is no power output from the load terminals of your charge controller.

What the Load Terminals on a Charge Controller are For?

You can connect an appliance’s terminals to the load terminals instead of connecting it directly to the battery or to an inverter connected to the battery.

This has the benefit of being able to automatically disconnect the appliance if the battery voltage drops below the voltage considered safe for battery use (the low voltage disconnect voltage).

Pay attention to the polarity of the load terminals and the power limits of the charge controller.

For more information, check the section: How to use the load terminals of a solar charge controller.

Why you Need the Load Output Terminals on a Charge Controller?

The load output connection on a charge controller is a convenient way to take advantage of the inbuilt features of the charge controller – over-discharge protection to safeguard your battery against damage from deep discharge, overcharge protection, and monitoring of power used by the appliance.

Monitoring of an appliance’s power consumption is useful in understanding the appliance’s actual power use compared to expected and whether for instance, you need to upgrade your solar system – solar panels or battery to meet your growing energy requirements.

The load output terminals also supply a regulated voltage output to your appliance and guard against variations in the battery voltage during the charge and discharge cycles (up to a limit).

Do You Have to Use the Load Output Connections on a Solar Charge Controller?

No, you do not have to use the load output connections on a solar charge controller.

Using them has an advantage – not only do they usually protect the battery from deep discharge by automatically disconnecting it when the voltage drops below a set level for the battery.

There is also the added advantage of being able to monitor the current and power drawn by the appliance( depends on the charge controller make and model) and the ability to switch ON/OFF the appliance(s) centrally at the charge controller (depends on charge controller make and model).

Lastly, the load output terminals supply a regulated voltage supply to the appliance.

So in the event that the battery voltage is high say 14V during the charging cycle, the voltage at the charge controller output terminals stays at 12V.

The disadvantage of connecting appliances to the load output terminal of a charge controller is that you can only power appliances up to limited power consumption – check the owner manual of your charge controller for the maximum current draw available at the output terminals before connecting an appliance.

So, appliances that draw large currents in excess of what the load output terminals can handle should be connected to the battery directly.

Inductive loads like DC refrigerators and inverters should also be connected to the battery directly.

What to Do if a Solar Charge Controller Has No Load Output Terminals?

If a solar charge controller has no load output terminals then no need to worry. You can connect the appliances to the battery or if using AC appliances, connect them to an inverter connected to the battery.

When you plug the AC appliances into the inverter, you rely on the inverter to automatically disconnect the appliance if the battery voltage drops below the set voltage level.

You may also be able to get a programmable low voltage disconnect relay (available on Amazon) that you connect at the battery terminals to supply the appliance power that then disconnects battery power to appliances at set voltages.

Check that the low voltage disconnect relay can handle the current draw of your appliance.

Is the Output of a Solar Charge Controller AC or DC?

The output voltage and current that your appliance receives when connected to the load output terminals of a solar charge controller is DC. So only connect appliances that use DC power.

This charge controller essentially controls the charging rate and discharge rate of the battery and does not do any power conversion from DC to AC.

Examples of such appliances are DC lamps, DC radios, DC LED lights.

Should you need to use an AC appliance, then you connect an inverter to the battery terminals.

How to Use the Load Terminals of a Solar Charge Controller?

The load terminals have a limit to how much power they can supply.

To use the load output terminals safely, you need to pay attention to the charge controllers’ output voltage, output current, and polarity of the terminals (which terminal is positive or negative) as you connect the appliance.

So, first, make sure that the DC power requirements of your appliance are within the limits of the solar charge controller.

Load output current: Make sure the current draw of the appliance does not exceed the maximum current draw of the charge controller.

For example, if the maximum load current that can be drawn from a charge controller is 5 amps, do not connect an appliance that draws 7 or 10 amps otherwise the appliance will not work properly and you risk damaging the charge controller.

Load output voltage: If it is a 12V rated charge controller, only connect appliances that use 12V.

Connecting appliances that use a lower voltage such as 5V will damage the appliance.

The polarity of the charge controllers: Most DC appliances have a positive and a negative terminal.

Make sure you connect the appliance’s positive terminal to the matching terminal on the solar charge controller and the negative terminal to the solar charge controller’s negative terminal.

Related questions

Do the Solar Charge Controller Load Output Terminals Always Have Power?

If the solar charge controller load output is working properly and it is connected to a battery with sufficient charge then the load output terminals will have power.

On some charge controllers, it is possible to manually switch the load output ON or OFF so check your charge controller documentation if this is the case.

Should the battery voltage drop below the charge controller’s low voltage disconnect voltage, then it will disconnect the load and there will be no power until the battery has been charged sufficiently and has attained the set charge controller reconnect voltage.

(Note – this may vary from the charge controller to another).

Also, note that some charge controllers’ load outputs are programmable. You may be able to switch ON/OFF load for a preset time or come on automatically at dusk and off at dawn.

Why Solar Charge Controller Load Output Terminals May Have No Power?

Check that the solar charge controller load output terminals are not manually switched off (some controllers have an On/Off switch or are not programmed otherwise.

Final Word

Solar charge controller output terminals are useful for protecting the from over-discharging and the connected appliance from being subjected to potentially harmful voltages.

So, connect appliances to the load output terminals if you need to take advantage of this feature. make sure the appliance’s maximum current draw does not exceed what is supported by the charge controller.

For controllers without the load output terminals, you can connect the appliance directly to the battery, or in case of an AC load, connect it to an inverter powered by the battery.

Should your solar charge controller output terminal not be working, check that the battery has sufficient charge, that the solar controller load terminals are not switched off, and if it has programmable load terminals that features like timers or dusk to dawn feature is not activated (depends on the controller make and model).

It is also possible that the controller is faulty.

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