In this article we will discuss Battery and solar panel compatibility at different voltages: the role of the MPPT.
Can different voltage panels and batteries be connected?
Obviously a 12V solar panel is compatible with a 12V battery, and a 24V solar panel is compatible for 24V battery charging. The doubt arises when the voltage of a panel does not match the voltage of the battery to be charged and also when we use 60-cell panels that are incorrectly called 24V and are not, those that are between 220 and the 275W usually.
Before explaining each of the cases, it is important to highlight the importance of an MPPT regulator working in the process.
The cases could be:
In this case, the 24V panel can charge a 12V battery thanks to the MPPT controller. This happens because the MPPT does not care about the input voltage, as long as it is equal to or greater than the minimum starting voltage of the regulator for the battery that is connected to it. We recommend consulting the technical sheet to make sure.
In this case, the 12V panel, although connected to an MPPT regulator, cannot charge a 24V battery. This occurs because the MPPT controller is not capable of raising the panel voltage to the point needed to charge a 24V battery. That is why in this case it will be necessary to use at least 2 panels of 12V or 2 panels of 60 cells or connected to the network, since one alone is not capable of offering the necessary voltage throughout all the hours of sunshine.
An MPPT controller makes sense when the input voltage is always higher than the working battery voltage. We also gain in efficiency since we will have lower losses by going to lower voltages.
How to use a 24V solar panel with a 12V battery
To connect a solar panel to a battery, you must first make sure that the panel and the battery have the same voltage. Of course, this is much easier if the panel is battery compatible, but there is also a way to change the voltage of your battery system to make it compatible with the panel. In the case of a 24V panel and a 12V battery, you can make the connection by connecting two batteries through a series connection.
Connect the negative end (terminal) of one 12V battery to the positive end (terminal) of the second battery using a battery cable.
If you are going to make a series connection, which is a process that doubles the voltage without changing the capacity (amps per hour). If you connect the battery in parallel (positive to positive and negative to negative), you double the capacity, but the voltage remains constant.
Connect a second battery cable to the positive terminal of the first battery.
Connect a third battery cable to the negative terminal of the second battery.
Connect the two loose wires to the appropriate positive and negative inputs on the solar panel or other device.
Most solar panel installation specialists recommend placing a charge controller between the batteries and the panel to protect both devices from changes in power flow, as the amount of sunlight and the power output of your panels , change. If you decide to use a charge controller, connect the batteries to the controller, and the controller to the solar panels.
Use an inverter if you want to convert direct current (DC) from your batteries to alternating current (AC), the type of current used in household connections. You can connect an inverter directly to the batteries or to a charge controller.
Make sure you are using the same kind of battery cable for each connection.
As with any type of electrical connection, be careful when coming into contact with the wires and connecting parts.