Series vs Parallel Solar Panel Wiring Basics: Volts, Amps, Costs & More Explained

Oct. 17

Here at The Solar Lab, we know that getting started with solar can seem a bit intimidating at first. There’s a lot of new terminology to familiarize yourself with, not to mention a seemingly endless number of components and brands. Plus, even the idea of wiring electrical equipment together can be pretty off-putting for total newbies. This is why we try our best to provide these simplified guides to solar basics. We want you to get the most out of your equipment, and learn just how easy it actually is to get into the world of solar.

Today’s lesson is all about wiring solar panels. More specifically, it’s a basic breakdown of the two most common ways to wire solar panels together: series and parallel solar panel wirings. We’ll also touch on how you can even do a combination of both wiring methods to get the best of both worlds and ensure compatibility with your charger controller or inverter.

Don’t worry, we’ll keep this as simple as possible and we won’t bog you down with unnecessary terminology—just what you need to know, and why it matters. So, let’s dive in!

Solar Panel Wiring 101 – Wiring Panels in Series vs. Parallel

Pretty much every single solar panel you pick up is going to come with two wires hanging off the back of it: one positive and one negative. It sounds straightforward, but wiring panels can get a bit more complicated when you start to consider the total size of your solar array (the total grouping of all of your solar panels). The specifications of your charge controller and the type of panels you’re using can also be important factors when determining how you should wire your panels together.

Whether you’re just wiring a few small folding solar panels together to charge a portable power station, or you’re putting together a more elaborate off-grid system, getting the basics of solar panel wiring down will save you a headache in the future. So, here’s a breakdown of the two wiring styles:

Wiring Solar Panels in Series

Think of wiring in series like creating a “daisy chain” of solar panels. You connect the positive terminal of one panel to the negative terminal of the next, repeating the process until you’ve linked all of the solar panels in your array together. The open ends of this string then connect to your charge controller or your inverter if it has a built-in charge controller.

The key thing to remember with series wiring is that volts add up, while the amps stay the same. For example, if you have six 200W solar panels, each with 25 volts and 10 amps, wiring them in series would give you an output of 150 volts and 10 amps. The amps stay at 10, but the voltage of each panel combines to give you that total.

The Pros of Series Wiring Solar Panels:

Simplicity: Fewer parts, fewer wires, and less complexity. For basic setups, this is often the way to go.
Cost-Effectiveness: Series wiring often requires fewer components, making it cheaper when you’re first getting started.
Manageability: With fewer cables and components, there’s less that can go wrong, and your system stays really simplified. You also reduce the risk that you could overload your system, which can be a bit of a worry for complete beginners.

Cons of Series Wiring:

The main issue with series wiring is the fact that all of your solar panels are reliant on one another. Basically, if one solar panel is covered by shade, or just plain broken or malfunctioning, it can impact the overall performance of the entire array. In other words, if one link in the chain has an issue, it can reduce the efficiency and output of your entire solar panel array.

Since every solar panel is dependent on each other, a single solar panel can impact everything.

Wiring Solar Panels in Parallel

When wiring in parallel, all the positive terminal wires are connected together, while all the negative wires are connected together. Unlike series wiring, in parallel, amps add up, but the volts stay the same. Using the same example of wiring together six 200W solar panels, wiring them in parallel would give you 25 volts and 60 amps (since each panel’s 10 amps are added together).

The Pros of Parallel Wiring Solar Panels:

Each Solar Panel Stands Works Independently: If one of your solar panels is shaded or malfunctions, it doesn’t affect the rest of your solar panel array. Each panel operates on its own, so your total power output remains more consistent.

Increasing Total Amperage: Since the amps add together, you increase your system’s total amperage when you wire in parallel, which can be useful for certain setups and charge controllers that require a higher amperage rating.

Cons of Parallel Wiring:

The main issue with parallel wiring is just the fact that it increases the overall complexity of the setup. In all likelihood, you’ll need additional components, like thicker wires to handle the higher amperage, branch connectors to keep things tidy, and fuses to protect your system and solar panels. For those who are just getting started, this added complexity can be off-putting.

Needing more components also tends to result in higher upfront costs, which can be another roadblock for beginners. The thicker wires and cables tend to be more expensive, plus higher amperage ratings mean you need to add fuses to protect your solar panels, which, while cheap, are still an additional cost.

On top of all that, working at a higher amperage does come with an added safety risk. Basically, a parallel system requires greater attention to safety, as well as additional wires.

Example Setup: Connecting Solar Panels to a Rich Solar 3K Inverter

Let’s say you’re working with a pretty standard solar inverter, like the budget-friendly Rich Solar 3K Inverter. This inverter has a built-in charge controller that can handle up to 80 amps and between 60 to 115 volts.

When wiring your solar panels to it, you have to ensure that the voltage and amperage of your array fall within the specifications of the charge controller. To continue our example of using six 200W panels, wiring them strictly in series would give you a total of 150 volts, which is too high for the inverter’s 115V limit. On the other hand, wiring strictly in parallel gives you 25 volts, which is too low for the 60V minimum required. So how do you make it work?

Combining Series and Parallel Wiring – The Best of Both Worlds

To make this solar array compatible with the Rich Solar 3K All-in-One Inverter, you would need a combination of both series and parallel wiring. Here’s how you would do this:

Divide your array into two sets of three panels each.
Wire each set of three panels in series. This gives you a 75V output for each combined wire.
Then, wire those two sets in parallel. This doubles the amperage to 20 amps while keeping the voltage at 75V.

This combination of series and parallel wiring fits perfectly within the inverter’s specs, as it keeps both the voltage and amperage at safe levels while maximizing efficiency. This combination of a series and parallel solar panel wiring is actually a pretty common method, especially as more people are embracing the simplicity of having an all-in-one inverter that has a built-in charge controller.

Why Solar Panel Wiring Methods Matter

Choosing between a series, parallel, or combined wiring method doesn’t have to be as complicated as it may seem from an outside perspective. At the root of the decision is just finding a way to match your solar panels to your output goals and the specs of your other equipment.

Series wiring is simple, but sensitive to shading issues, as well as individual solar panel failures. Parallel wiring offers a bit more flexibility and helps you overcome the “weak link in the chain” issue you can encounter with series wiring, but it’s also more complex. While combining the two can help you achieve the best of both worlds.

Final Thoughts

Each wiring method can have its advantages and disadvantages, and in many cases, the best option is a hybrid setup that combines both. If you’re feeling confused, check out the video version of this article, which we have linked for you up at the top. You can also check out our Intro to Solar Mini Series, which covers all of the basics and is a great place to start if you’re just getting into solar.

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