How to Connect Two or More Solar Panels Together

Connect Two Or More Solar Panels Together

Connecting multiple solar panels together can enhance the efficiency and power output of your solar power system.

This can be done in three primary configurations: parallel, series, and series-parallel. Each method has specific applications and benefits, depending on your power needs and system design.

When doing this, it’s very important to understand the differences between the three methods. Because two of the ways change the total voltage the panels put out, which can change compatibility with solar charge controllers and portable power stations.

If you have a portable power station, start by figuring out the input limits it has. Here is an article that teaches you how.

It’s also important to know the voltage of one panel if you plan on combining two or more in series or series-parallel, which will increase the voltage. Here is an article on how to find the voltage of a panel.

Now, let’s get to the three methods. I will also list a couple of examples and how I would go about combining two panels or more, depending on the power station input limits.

Parallel Connection

Purpose: Increases current while maintaining the same voltage.

Materials needed: An MC4 Y branch made for the number of panels you plan on combining. Here is one for combining two, here is one for three, and here is one for four. For a simple parallel connection, you just need one pair.

Steps:

1. Identify Terminals: Locate the positive and negative terminals on each solar panel.
2. Connect Panels:
   • Connect all positive terminals together using one of the MC4 Y branches.
   • Connect all negative terminals together using the other MC4 Y branch.
3. End Connections:
   • The combined positive and negative terminals will connect to your charge controller or adapter that connects the panels to a power station.

Example: If you connect two 12V, 5A panels in parallel, the output will be 12V (working voltage will be higher), 10A. A 12V 100W panel doesn’t actually output 12V, but has a working voltage of around 18V.

Application: Ideal for systems that require higher current, such as battery banks in off-grid systems, or portable power stations that have a voltage limit of 12-30V.

Series Connection

Purpose: Increases voltage while maintaining the same current.

Materials needed: Two or more solar panels

Steps:

1. Identify Terminals: Find the positive and negative terminals on each solar panel.
2. Connect Panels:
   • Connect the positive terminal of the first panel to the negative terminal of the second panel.
   • Continue connecting in this manner for additional panels.
3. End Connections:
   • The remaining positive terminal on the first panel and the negative terminal on the last panel will be connected to your charge controller or power station.

Example: If you connect two 12V, 5A panels in series, the output will be 24V (working voltage will be higher), 5A. A 12V 100W panel doesn’t actually output 12V, but has a working voltage of around 18V. Remember to combine the voltages to ensure the solar charge controller can handle the total voltage output.

Application: Useful for systems requiring higher voltage, such as grid-tied systems or certain charge controllers. Also useful for combining solar panels to connect to power stations with an input voltage limit of 30+.

Series-Parallel Connection

Purpose: Combines series and parallel connections to increase both voltage and current.

Materials needed: An MC4 Y branch made for the number of panels you plan on combining. Here is one for combining two, here is one for three, and here is one for four. For a series-parallel connection, you need one pair.

Steps:

1. Group Panels: Divide your panels into pairs or groups.
2. Series Connection:
   • Connect each pair or group in series first, as described above.
3. Parallel Connection:
   • Connect the series groups in parallel.
   • Combine all positive terminals of the series groups together.
   • Combine all negative terminals of the series groups together.
4. End Connections:
   • The combined positive and negative terminals connect to your charge controller or inverter.

Example: If you connect four 12V, 5A panels in a series-parallel configuration (two series groups of two panels each in parallel), the output will be 24V (working voltage will be higher), 10A. A 12V 100W panel doesn’t actually output 12V, but has a working voltage of around 18V.

Application: Suitable for large systems needing both higher voltage and current, balancing the benefits of both series and parallel connections. Some power stations use charge controllers that supports both a high voltage and a high current.

VOC Vs VMP

Voc is the open circuit voltage and what the panel outputs when not under load. Vmp is the working voltage under load.

The input limits of a power station listed by a company can be Voc or Vmp. It’s usually not clear which they go by, unfortunately. The best idea in my experience is to not exceed the voltage limit with either the combined Voc or Vmp of your panel(s).

A charge controller with a 40V input limit might work great with a panel that has a Vmp of 38 and a Voc of 42, when the sun is out. But then when the sun goes down and the voltage increases to 42, it could complain that the voltage is too high, resulting in you having to unplug and plug in the panel again in the morning when the sun comes out. This is true for some power stations, and there is no general answer or solution to how power stations behave.

If you have had a problem like this, it’s likely because of the above.

Power Station Examples – Scenarios And Solutions

Let’s imagine that we want to combine two or more panels and connect them to certain power stations.

Power Station Example 1

This power station has the following input limits: 12-30V, 5.5A, 100W max.

We need to stay within the 12 to 30 volt range, or the power station won’t charge. We can exceed the 5.5A limit (check with the manufacturer of your power station model to make sure it is ok) and connect more than 100W of panels, but the power station is going to regulate the amperage and limit it to 5.5A.

If we have a 100W panel that can produce 5.5 amps at 18 volts (which is common these days), we’re already close to the 100W limit.

Connecting the 100W panel to another 100W panel is possible, but it will not improve the charging speeds under great conditions. It will be very useful in not so great conditions though, like on cloudy days or when the sun is low on the horizon.

Because we need to stay below 30V, and one 100W 12V panel outputs about 18V, we can only combine two panels in parallel, not series.

If we have a 50W panel and would like to add another 50W panel, the charging speed is going to increase and we will get closer to the 100W limit. Again, this can only be done with a parallel connection.

Power Station Example 2

This power station has the following input limits: 14-40V, 10A, 200W max.

In this example, we can connect two 100W panels in either parallel or series, as long as the panel has a working voltage below 20V. If we combine two 100W panels with a working voltage of 22V, the 40V limit will be exceeded and the power station won’t charge.

Two of these panels connected in parallel will get us close to the 10A limit, and 200W.

If our panels are 24V and have a working voltage of 38V, we can only do a parallel connection, since one panel on its own is close to exceeding the voltage input limit.

Power Station Example 3

This power station has the following input limits: 40-100V, 25A, 1000W max.

Now the “issue” is that we need to connect panels with a combined working voltage of at least 40V for it to charge.

Combining two 100W 12V panels in parallel will not do that, since it would output the same voltage as one 100W 12V panel (around 18V). Two panels wired in series would likely also not work, since the combined voltage would be around 36 volts.

If we add a third 100W 12V panel and connect them in series, we will get a combined voltage of around 54V. That works, and now the power station will begin charging. Add a fourth panel, and you’re still within the voltage range.

We can also combine two 24V panels in series. One 24V panel will output around 36V, so two would output about 72 volts. That works, because it’s within the 40-100V range.

How do we get close to the 1000W limit though? Well, we can do a series-parallel connection which will increase both the voltage and the amperage.

If we make two pairs of 250W 24V panels (four panels in total), connected in series, which we then connect in parallel with the MC4 Y branch, we will get a combined voltage of 72, and a combined amperage of around 16.

Now we’re utilizing both a high voltage and a high amperage, and can push the charge controller in the power station to the limit.

When a power station has input limits that allow both a high voltage and amperage, focus on getting close to the voltage limit first, then add amperage to increase the charging speed further.

Tips for Connecting Solar Panels

• Use Proper Cables: Ensure cables are rated for the voltage and current of your system. Combine the amperages of your panels if using a parallel or a series-parallel connection, and ensure the wires and any adapter used is able to handle the total amperage safely.
• Avoid Mismatched Panels: Using panels with different voltages or currents can lead to inefficiencies.
• Check Compatibility: Ensure your charge controller, inverter, or power station are compatible with the combined output of your solar panels. Read this article if you plan on connecting panels to a power station.
• Install Fuses or Breakers: To protect your system from overcurrent, use fuses or circuit breakers.
• Don’t connect two panels with built-in charge controllers: The panels you combine can’t have solar charge controllers. If they do, they must first be bypassed. The combination of panels can then be connected to a charge controller or a power station.

Related Articles

• Do power stations by X come with solar panels?
• How fast will a solar panel recharge my power station?
• Can I exceed the watt input limit of a power station?
• How to improve the efficiency of my solar panel?
• Do solar panels work when it’s cloudy?
• How to find the input limits of a power station

Conclusion

Connecting two or more solar panels together can significantly enhance the performance of your solar power system.

By choosing the right configuration—series, parallel, or series-parallel—you can tailor the system to meet your specific energy requirements.

Proper connections, compatible components, and safety measures make sure you will have an efficient and reliable solar power setup.

Please leave a comment if you have questions.