Note: You need to make sure that all of the cables and adapters you use can handle the total voltage and amperage when you connect two or more solar panels together. Not doing so might result in a fire.
Can You Connect Two Renogy Solar Panels Together?
Most solar panels are used to produce electricity to charge batteries, and they’re becoming more and more popular.
One company that manufactures solar panels is Renogy, and its solar panels come in a lot of different sizes and forms.
I have two Renogy panels permanently installed on the top of my RV, and they keep my portable power stations like the Jackery Explorer 1000 (click to view on Amazon) charged.
If you’ve never heard of portable power station/solar generator, it’s basically an all-in-one box with a battery, charge controller, and usually an inverter that powers AC outlets and other type of ports.
So how did I connect two Renogy panels together? That’s what I want to cover in this article where I go over the basics of how and what you need to know.
Of course, this can be done with solar panels from other brands as well. I am just using as an example in this post.
As always, feel free to leave a comment if you have any questions.
Things you should know before connecting two solar panels together
Connecting two panels together is easy to do, but it’s important that you understand the different ways to do it and why it matters.
Let’s start by taking a look at a Renogy solar panel.
Different panels with different ratings
There are more differences between the Renogy panels on the market than just the watts.
Some are sold with solar charge controllers, some are not. Some come with bare wires, while most use MC4 connectors.
A solar charge controller should be used when connecting the solar panel directly to a 12V battery, like an RV or car battery.
You shouldn’t use a solar charge controller if you’re connecting the panel to a portable power station, also known as solar generator, because most of them have a charge controller built-in (check yours to be sure).
The smallest Renogy panels, known as the maintainer panels, have neither a charge controller or MC4 connectors. These are meant to be connected directly to a 12V battery to trickle-charge it and keep it from draining completely.
So which panel do you need?
I have collected some of the different models and put them on a table, to make the differences clearer.
Notice the difference in watts, volts, charge controllers, and extra features.
Most Renogy panels larger than 50W use what are called MC4 connectors. There are two MC4 connectors on each panel, a positive MC4 male and a negative MC4 female.
Note: The picture above shows MC4 connectors that are wired the opposite way of a Renogy panel.
MC4 connectors are easy to connect and disconnect, it’s as simple as plugging one into the other.
The charge controller
If the solar charge controller regulates the electricity produced by the panel to charge the battery, you should always connect one to protect the battery, right?
Yes, but depending on what you connect the panels to you might not need to add one.
That’s why Renogy sells different configurations and kits, for different uses.
For portable power stations
Portable power stations, like the Explorer 1000 I mentioned earlier, has a built-in charge controller.
Jackery has put one in its power station so you don’t have to go out and get a charge controller as well as a solar panel, it’s enough to just get a panel.
It’s important that you don’t get a panel with a charge controller if your power station has one built-in.
For 12V batteries like in a car, RV, van
If the plan is to connect the panel directly to an RV battery with battery clamps, a charge controller is needed.
Unless it’s a very small solar panel, like the 5W or 10W which are not powerful enough to do any damage to the batteries, at least that’s what Renogy says.
Why the specifications of a solar charge controller matter
A solar charge controller regulates the produced electricity, but only if you connect solar panels it can handle.
Therefore, it’s important to know what the charge controller can handle.
If it’s a power station, you’ll find this information in the manual or by the input port on the power station.
It might say “Don’t exceed 30V”. What that means is that we should get a solar panel that has a VMP below 30V, or the charge controller won’t do anything.
In the manual, it might also say “max 10A”. This is an amperage limit.
It’s not recommended by manufacturers to exceed the amperage limit, especially not with external solar charge controllers.
I have put together this table to demonstrate how different power stations and solar charge controllers have different input ratings.
There are also different type of charge controllers. The most popular ones are PWM and MPPT.
MPPT is better overall because it’s more efficient and works better than PWM in bad conditions when the sun isn’t very strong.
Alright, so how do I connect two panels together?
Everything I have told you so far might seem like unnecessary information, but now you’ll see why it all matters.
There are two main ways to connect two solar panels together, either in parallel or in series.
A parallel connection will add the current (amps) together but keep the voltage the same.
For example, two of the Renogy 100W Renogy panels connected in parallel would output 20.4V and almost 10A.
A series connection will do the opposite and add the voltages together but keep the total current the same as if you’ve only connected one panel.
The same two Renogy 100W panels used in the example above connected in series would output 40.8V and almost 5A.
As we saw in the table above where I list a couple of charge controllers and power stations, they don’t share input limitations.
Some of them can handle two 100W 12V panels wired in series, while some can’t.
This is why it’s important that you understand the difference between parallel and series when you connect two or more solar panels together.
Also, no matter whether you do a series or a parallel connection, you need to make sure that all of the adapters and cables you use can handle the total voltage and amperage.
In a parallel connection, you connect all the positive wires separate from the negative.
Then you do the same with the negative wires, separate from the positives.
This is done with an MC4 Y branch like this one by BougeRV (click to view on Amazon).
The BougeRV Y branch I link to is made to connect two panels together, but you can find other configurations on the same listing for connecting three or four panels.
If you plan on connecting three or more panels, make sure the adapter and cables used can handle the total amperage.
What this will do is add the amperages together, while keeping the voltage the same.
If you have a power station that can’t handle voltages over 30V and you want to connect two Renogy 100W 12V panels to it, you must do it in parallel since two of them connected in series would exceed the 30V (20.4 times two equals 40.8).
The 20.4V number comes from the table above where I compare different Renogy panels.
In a series connection, the amperage stays the same as if you would’ve only connected one panel, but the voltages are combined.
If we use the same example as above but do a series connection, the voltage would end up being 40.8V.
A series connection does not require any extra adapters. All it takes is that you connect the MC4 male connector from one of the panels to the MC4 female connector on the second panel.
The more advanced way to go – A series-parallel circuit
A series-parallel connection will combine the two ways, which is necessary with some power stations to utilize all of the power generated.
I am not going to dive into that in this post, but you can find more information about that if you google series-parallel circuit.
What if my panel came with a solar charge controller?
If you’ve bought a solar panel already that included a solar charge controller, you might be able to add a second panel before connecting them to the charge controller.
But it’s going to depend on the charge controller.
What you’ll have to do is check the limitations of the charge controller, then consider how adding a second panel would change the total current or voltage and if the charge controller can handle it.
Can you use two different solar panels?
You can connect two different solar panels in either parallel or series, but it’s not recommended.
The reason it’s not recommended is that it will most likely waste some electricity, unless the panels have the same voltage or current ratings.
If you do a parallel connection, you should make sure they have the same, or very similar, voltages. Otherwise, the panel with the higher voltage will be slowed down to the voltage of the panel with the lower voltage.
If it’s a series connection, you want them to have the same current. Otherwise, the panel with the higher current will be slowed down to the current of the panel with the lower current.
It’s fine to do, but be aware of the downsides.
Parallel Vs Series? Which should I use?
If you check the input limitations of your solar charge controller or input on the power station, you should be able to tell whether to do a parallel or a series connection.
If you’ve done this and figured out that you’re good on the voltage but will exceed the amperage, you should read the manual or ask the manufacturer of your charge controller or power station whether it’s safe to exceed the max input amperage or not.
I have exceeded the amperage on the input on my Jackery Explorer 500, but I wouldn’t do it with a charge controller like the Victron since it has a fuse that will blow if I exceed it.
If you can use either parallel or series with a charge controller, which is best depends on how your panels are used.
Parallel will be better if one of your panels is partially shaded throughout the day, because then the second panel will still be able to provide the same power.
In a series connection, the second panel would drag down the first panel with it.
Series will, however, be more efficient during the hours of the day that the sun isn’t the strongest, as in morning and evening. Also when it’s cloudy.
This ended up being an article that is a little bit all over the place, but I hope I haven’t confused you too much.
I hope that you’ll be able to look at a solar charge controller or power station and be able to figure out whether two panels are compatible, and which way to connect them.
Please leave a comment down below if you have any questions, or something to correct/add. Thanks.