A charge controller is a component used to regulate the charge flowing into the battery. It is connected directly to the battery, and in some cases, it may have a load terminal.
If your charge controller has a load terminal, connecting a direct load to the charge controller is possible. Implying, that you can have loads connected directly to the battery and others on the charge controller, which increases the effectiveness of your system.
However, you do not necessarily need a load connection on a charge controller. Besides, not all types of loads can be wired on a charge controller.
Stick around as we discuss all those issues and how you can wire a load to a charge controller, and much more.
What are load terminals?
When connecting a device to a power device, you must connect at the terminals. Basically, load terminals are external device connection points in a charge controller.
These terminals are mostly found on the output ports and ensure an intact connection between the two devices for an efficient current flow.
Load terminals in a charge controller produce direct current. Let’s discuss this deeper.
Generally, a solar system incorporates a panel, charge controller, batteries, and inverter.
The panel absorbs the solar energy and converts it to direct current. This current is directed to the charge controller before leaving the battery.
The inverters are connected directly to the battery, converting the direct current to the alternating current.
Since the current on the charge controller has not passed through the inverter, it will be direct current.
Additionally, considering that different loads are compatible with a particular current type. The load connected to the charge controller terminals should be strictly compatible with the direct current, either direct or alternating current.
Light bulbs are an example of loads connected to the load controller’s load terminal. To add, you should also note the output voltage at the load terminals. Ideally, you should never connect loads with a higher voltage than this.
Why do I need a load connection on a charge controller?
Let’s forget about the load connection in a charge controller for a second.
All the power from the charge controller should be directed to the battery. What happens when the battery is full? Remember that the charge controller is designed to prevent the battery from overcharging. Consequently, it can’t direct more charge to the batteries when it is complete.
As a result, the charge controller is designed to reroute the excess current directly to the inverter, which connects to the ac loads for consumption.
Let’s assume that there is no load at the terminals. What happens to the excess current? This question introduces us to why you need a load connection.
You need a load connection on a charge controller to take advantage of the surplus current generated by the device after the battery bank is full.
However, it is not necessary to have a load on the charge controller’s terminals. This device has internal crafting that makes it possible to deal with excess current safely.
However, you should ensure that the load connected to the charge controller has the exact voltage requirements and its current rating is significantly below the current rating of the charge controller.
In other words, you cannot connect a 10 amp load to a 10 amp charge controller. However, a 5 amp device would be okay. Essentially, the power requirement of the load should be lower than the power supplied by the charge controller.
How do you wire load to the solar charge controller?
Before we dive right in, we will assume that you have everything is connected well. That is, the solar system is functioning perfectly.
Briefly, you should connect the current from the solar panel to the solar charge controller. The current from the controller should flow directly to the battery, which later connects to the inverter.
You can check if you have made the solar system connection correctly by connecting a load such as a phone to charge at the inverter outputs.
Let us look at how you wire a load to the solar charge controller with that out of the way.
Step 1: Choose the load
Not every load can be wired on a charge controller.
Since the charge controller wiring doesn’t involve an inverter, the ideal load should be compatible with direct current.
Additionally, the nominal voltage of the load should be equal to the controller’s voltage. That means you should not connect a 24 volts load to a 10 amp load.
Lastly, you need to look at the current rating. Ideally, the current rating of the load should be significantly lower than the current rating of the charge controller.
To sum it up, the power drawn by the load should be lower than the power supplied by the charge controller
Step 2: Disconnect the photovoltaic arrays
You can wire the load successfully without interrupting other connections, which puts you at a high level of shock risk.
Therefore, it would be best to disconnect the charge controller from the solar panel.
Step 3: Connect the load
Wiring the load is relatively easy.
First, identify the positive and negative terminals of the load and charge controller.
Next, connect the negative terminal of the load to the negative terminal of the charge controller. Do the same thing for the positive terminal.
Step 4: Connect PV
After, restore the connection between the charge controller and the solar panel.
Step 5: Check the connection
That is all needed to wire a load in a charge controller completely. You can check if you have done the wiring correctly by checking the current flow to the load. In other words, the load should start functioning if the switch is on.
For instance, if the load is a bulb, it should start lighting.
You can also look at this video if you are stuck.
What is the load connection to switch on my charge controller?
Additionally, you can add a switch on the charge controller to regulate the power consumption by the load.
When adding the switch, you should be careful to correctly connect the negative terminal and positive terminals.
Further, you should ensure that the voltage and current rating of the switch is compatible with the current and voltage rating of the charge controller.
Can I connect an inverter to a solar charge controller?
An inverter is a solar system component used to convert direct current to alternating current. Typically, it receives its input from the battery while the other is connected to the mains.
On the other hand, the charge controller gets its input from the solar panel and outputs it to the battery. In some cases, if the charge controller has load terminals, a load can be connected.
However, as we earlier said, the load connected to the charge controllers should be strictly compatible with direct current.
I understand that fact limits you on the type of devices you can connect to a charge controller. To remove this limitation, you might consider connecting an inverter to the charge controller’s terminals. But is that right?
This is it, you should never connect an inverter directly to a charge controller. A charge controller is designed to regulate the amount of power flowing into the battery, preventing overcharging, undercharging, and other battery issues.
That is why you can’t just use any controller on any battery. You should consider the current ratings and the voltage to ensure that the power requirements are compatible.
On the other hand, an inverter is designed to convert the DC flowing from the battery to the load and not connect to a charge controller.
A load connection on a load controller allows you to connect extra devices directly to the solar panel, enabling you to take advantage of the excess current and preserve the power in the battery for future use.
However, the charge controller must have load terminals where you will connect the load. The current on these terminals is direct current. Hence the connected load should be compatible with it.
Additionally, wiring a load on a controller is relatively easy. You simply have to connect the terminals, the positive cable from the load to the positive terminal, and the same thing for the negative terminal.
However, you should be pretty careful with electric shocks when wiring. You can prevent that by disconnecting the circuit.
We have discussed that and much more about load connections on the charge controller to help you have safe and secure wiring.
Eng. Matthew Joseph Nandirio is the Founder of walkingsolar.
After graduating from the University of Houston in 2002, matt started working as a Solar Electrical Engineer for several multi-national solar energy companies.
He has a wide range of experiences including solar system requirement analysis, planning, maintaining, debugging and even solar device development through research.
He now shares his 20 years of expertise through his articles on the walkingsolar website.
Further, he is also the author of two books on Solar Technology, “Solar Power for Villages” and “DIY Solar System for Dummies”.