Connecting solar panels in series vs. parallel. What’s the difference? And which solar connection type is best for van life?
We’re glad you asked! In this post we discuss the differences between connecting solar panels in series or parallel. We’ll also touch on the pros and cons for each type of connection and, ultimately, which connection we prefer.
So if you’re ready, let’s get to it!
Physical Wiring Differences For Solar Panels In Series vs. Parallel
Every solar panel comes with two attached output cables; one POSITIVE cable and one NEGATIVE cable. With these output cables, you can attach multiple solar panels together to create an ‘array’. And there are two DIFFERENT ways to connect all these output cables together.
One way is to connect your solar panels in ‘series.’ The other method is to connect your solar panels in ‘parallel’.
Both ways have their pros and cons. And we’ll get to that. But below we show you what the physical connection difference looks like.
Solar Panels In Series
For solar panels connected in series, the NEGATIVE output cable of the first panel is connected to the POSITIVE output cable of the second panel. Then the NEGATIVE output cable of the second panel is connected to the POSITIVE cable of the third panel. And so on, for however many solar panels you have.
Finally, the POSITIVE cable of the first panel and the NEGATIVE cable of the last panel are connected to the solar charge controller.
Related read: What’s a solar charge controller? And do you need one?
Solar Panels In Parallel
* Solar fuses are technically required in this wiring example, but are excluded here for simplicity.
For solar panels connected in parallel, the POSITIVE output cables from all the solar panels get joined together, using a branch connector. The same is done for all the NEGATIVE output cables; they get joined together using a similar branch connector.
The branch connectors take all the positive and negative cables and output a single POSITIVE and NEGATIVE line, which then gets connected to the solar charge controller.
Related read: How to fuse a solar array
How Series vs. Parallel Connections Affect Volts and Amps
In order to understand the pros and cons of series vs. parallel solar panel wiring, it’s important to understand how series and parallel connections affect the solar array’s electrical output.
Under similar situations, solar arrays connected in series and parallel will output the same amount of total watts (w). So if you have three 200-watt panels you will output close to 600-watts under perfectly ideal situations, regardless of whether they’re connected in series or parallel.
But the difference between series and parallel connections comes from the make up of volts and amps, which are the two ingredients that make up watts.
How Series Connections Affect Volts & Amps
It’s important to know that when connecting solar panels in series, the volts produced by each panel get added together. But the amps stay the same.
Therefore, if you have two solar panels that can output a maximum 18.6 volts and 5.86amps, then the solar array’s operating voltage has a potential to generate 37.2V but still only 5.86A.
How Parallel Connections Affect Volts & Amps
In a parallel connection, the amps generated by each panel get added together. But the voltage stays the same.
Therefore, if you have three solar panels that can output a maximum 18 volts and 11 amps, then the solar array’s operating voltage has a potential to generate only 18 volts but 33 amps of current.
Key Take Away
Remember This Difference
Series connections add VOLTS.
Parallel connections add AMPS.
Now we’ll discuss the pros and cons of the two different solar array wiring methods.
Pros & Cons For Series/Parallel Solar Connections
Here we’ll address each of the pros and cons, especially as it pertains to camper van life and RVs.
1. Simpler wiring process | Connecting solar panels in series means having to deal with less components. No branch connectors nor solar fuses. This saves on the overall cost of your solar system build.
2. Better for long wire runs | Voltage tends to drop across long wire runs. So series connections, which combines each panel’s voltage production, makes solar harvesting more efficient across long wire connections (think 25+ feet).
3. Ideal for 24V Systems | Since series connections adds volts, you MUST wire your panels in series if you have 24-volt batteries. If the solar array cannot product a voltage that is greater than the battery’s, the battery will not charge.
Broken panel shuts down whole array | If, for whatever reason, one of the solar panels malfunctions, the entire solar array will go down. That panel will either need to be replaced or the functioning panels will need to be rewired to exclude the broken panel.
Lower efficiency during partial shading | Partial shading drastically affects solar harvesting production, no matter if the panels are in series vs. parallel. But panels in series are more inefficient when partially shaded.
No problem when one panel breaks down | If one of your panels malfunctions, it does not hinder the solar production from your other panels.
More efficient in partial shade | Though partial shading is still detrimental to harvesting solar energy, parallels wired in parallel are more efficient at producing power than those wired in series.
More components are needed | To wire panels in parallel you’ll need branch connectors and – maybe – solar fuses. Read our solar fuse article to learn more if you’ll need them.
Less ideal for longer wire runs | Since parallel solar arrays carry significantly less voltage than those in series, this makes them less ideal for longer wire runs.
Thicker wires, maybe | Since amps are added up in parallel connections, you might need to purchase thicker wires. But this depends on the overall wattage of your solar array. Check out our solar wire sizing guide to learn more.
Which Connection Type Is Best For Camper Vans & RVs?
If you are building a camper van solar system, this is the most important series vs. parallel question for you.
And the answer is: IT DEPENDS!
Different people will give you different answers. But here is how we break it down.
Only 1 Panel? → Series
Since you’re not wiring multiple panels together, there’s no need to choose. Great!
Have A 24v System? → Series
You’ll need a solar array that produces a higher voltage in order to charge those 24v batteries.
Have 2 panels? → Parallel
Having only 2 solar panels means not having to deal with solar fuses, meaning this parallel connection isn’t so complicated or bulky.
Have 3+ panels? → Series
Simplicity is key when you have more panels. Keep the connections simple with a series connection.
Related read: Best solar panels for van life
Which Connection We Use For Our Camper Van
On our camper van, we wired two 180-watt solar panels in parallel.
We did this for two important reasons:
1. Maximize Production During Partial Shading
Living in a camper van, we knew we would be parked in a plethora of different lighting situations.
Sometimes our van roof would experience unlimited direct sunlight. Other times we’d experience plenty of partial shading from trees.
And since we planned to park in plenty of national parks and boondock on forest lands, combating the effects of partial shading by connecting our panels in parallel was important to us.
2. No Need For To Fuse Our Solar Array
Lastly, because we only intended to install two panels on our roof, we didn’t have to fuse our solar array system and didn’t have to worry about combining different wire sizes to create our array. Check out our other post about solar fuses to learn more.
Free Solar Resource!
Final Thoughts: Series vs. Parallel? Which Is Better For Solar Arrays?
When it comes to installing solar arrays on houses, the answer is more clear. Because there are more panels involved, wiring solar panels together in series provides more upside. You can keep wire thickness sizes to a minimum and you don’t have to worry about those pesky fuses.
But when it comes to wiring a much smaller solar array on a mobile vehicle, we think the answer becomes less clear.
In the end, the decision is up to each of us. Do we value wiring simplicity? Do we value maximizing production in partial shading situations?
We hope that by the time you’ve reached the end of this post, you have a greater idea of what type of wiring is best for your own solar array system.
If you have any questions, please let us know in the comments section below!