What’s the Difference Between Connecting Solar Panels in Parallel and Series?

The share of solar power in the U.S. keeps rising. As of 2022, Americans have installed enough solar panels to power 22 million homes. However, the technical aspects of installing a system are less important to most homeowners than the very fact of owning solar panels.

Most future owners wonder about the type of panels they’re about to purchase – whether they need monocrystalline, polycrystalline, or flexible. But that’s not the only thing to worry about or consider.

One of the critical aspects is understanding how to wire a solar panel. How do you know whether you should connect solar panels in series or parallel, or series-parallel? What is the difference? What are the ups and downs of using each connection type? These are the questions we’re going to answer in this article.

Solar Panel Wiring in Series

Satisfying your farm’s energy needs is only possible if the balance between current and voltage is perfectly calculated. Wiring solar panels in series allows you to accumulate voltage and keep the current constant.

Source: Battle Born Batteries

If you look at a solar panel, you will see two terminals: a positive and a negative. Сonnecting solar panels in series implies combining one panel’s positive terminal with another’s negative terminal. Such a system sums the voltage of all panels, and the current remains unchanged.

However, connecting solar panels in series is more than generating energy. It’s about the ability to power your home, so it needs to be converted with the help of an inverter (power supply, portable power station). This device will convert direct current to alternating current to power appliances and devices in your home.

Here are the four essential steps of a connection process:

It might seem like anyone with at least some idea of electrical appliances can handle this. But that’s not always the case. The steps described above illustrate the most primitive method, which gives only a general idea of how to wire solar panels in series. Should you require any assistance, contact system installers or solar technicians.

After figuring out how to connect solar panels in series, let’s explore the ups and downs of such a connection.

Pros:

• Since the current remains unchanged with this connection, the system does not require large-section solar panel series wiring, which is much more expensive than usual.
• Connecting solar panels in series is easier; it does not require special skills and, most importantly, additional equipment.
• The decision to wire solar panels in series is an ideal solution for regions with low-intensity sunlight, regardless of the time of the day.

Cons:

• The failure of one panel can disable the system. Even its shading can affect a solar panel series connection, reducing the entire battery’s efficiency.

While the serial connection is a popular way to assemble a system, let’s examine parallel solar panel connections in more detail.

Solar Panel Wiring in Parallel

Unlike the serial method, this one implies connecting the positive diodes of the panels. If you’re dealing with a large and powerful system, you will need a blocking diode in each parallel solar panel chain. It will protect the system against reverse currents. Alternatively, you can also use the charge controller for that.

Source: Battle Born Batteries

The difference between such a system is that the current strength grows and is summed up from all panels, and the voltage will be the same as that of each panel taken separately.

Here’s how you can handle the solar panel parallel connection:

• Determine the correct location of solar panels in parallel – they must be at a certain distance from each other, which is very important, they should not shade each other.
• Select the cable of the required section depending on the distance of the panels from each other.
• Connect all terminals using special junction boxes.

As you can see, solar panels in parallel or series are connected differently, and the latter is more complex. But the benefits it offers make this connection type more popular.

Pros:

• Optimal solutions if part of the roof is darkened or in conditions of mixed shading.
• The failure of one panel does not significantly affect the series-parallel solar panel.
• While connecting solar panels in parallel, charging the system and individual panels is faster.

Cons:

• Parallel solar panel wiring requires additional materials and equipment.
• This type of connection requires a thicker and more expensive wire.
• Optimally work at a high intensity of sunlight but are less effective in Northern regions as well as early mornings and late evenings.

At this point, you’re probably wondering how to connect solar cells and choose the most optimal way to achieve the mission.

Which Is Better for Solar Panels: Parallel or Series?

It is difficult to determine the best way to connect a solar panel, in series or parallel, and it all depends on the needs and conditions of each home. Let’s figure it out point by point.

Possibility of Failure in Series and Parallel Connection

To understand exactly what will happen to solar panels in series or parallel, let’s look at the following example.

A New Year’s garland — the good old-fashioned light bulb chains — is a series-connected system. If one lamp burned out, the whole garland did not work, and you had to find a replacement.

Modern garlands are connected in parallel. One or two lamps may not work, but the rest will give light — the same works for the parallel connection of panels. Therefore, the so-called war of solar panels parallel vs. series can finally end.

System Output Power

As mentioned before, power is the current multiplied by the voltage. How does it change depending on the type of connection? 

Suppose we have two devices in which the voltage is the same, but the current strength of one is greater. It means that the device’s power, where the current strength is greater, will also be greater. In other words, the solar panel in parallel is more powerful.

But that’s also true when two devices have the same current strength, but the voltage of one is greater. In other words, the solar panel in series is clearly more powerful. However, you need to consider other parameters to determine which system will be more powerful in your case.

Connection in One System of Panels of Different Sizes and Specifications

If you have a different power supply, you might wonder which is better: series or parallel solar panels. Let’s consider both cases. When connecting in series, we will get the summed voltage of different panels, and the current strength will be the same as that of the smaller module.

When connected in parallel, the current will add up, and the voltage limit will equal the smaller module’s voltage. The controller will reduce the current to the maximum allowable level if the current is too high.

Now let’s consider solar series vs. parallel:

• We have panels with such characteristics – 20V, 5A and 24V, 5.4A
• With a parallel connection, we get the following calculation – 20Vx (5A + 5.4A) = 208W.
• With a serial connection – (20V + 24V) x5A = 220W.

Using a serial connection when using panels with different technical characteristics is better. But, as always, we recall that these are theoretical calculations that do not consider other data and equipment indicators.

Nevertheless, they are taken as a basis and are always the most important. All other selection criteria for parallel vs. series solar panels will be individual and additional.

Solar Parallel vs. Series: Adding Panels

The ideal system is initially designed for the household’s requirements. But the circumstances may differ, like the lack of money at the installation time for the system to fully cover the needs, the electricity consumption could’ve, etc.

If you have to add panels, the connection scheme will not be fundamental, but using the correct accessory equipment will be important. However, it’s always the right call to install a system with the possibility of modernization immediately.

How To Connect Your Systems in Series

• Determine which cable on the solar panel is positive and which is negative – usually, the cables are marked, but if there are no marks, you can use a multimeter.
• The panels should be laid with their working surface down on the blanket – to have easy access to the cables and eliminate the energy generation during operation.
• Connect the positive cable of one panel to the negative cable of the other. You can check the correct connection with a multimeter.
• Connect the system to the charge controller. All solar panels are wired in series.

How To Set up a Parallel System

• Determine which cable on the solar panel is positive and which is negative – usually, the cables are marked, but if there are no marks, you can use a multimeter.
• The panels should be laid with their working surface down on the blanket – to have easy access to the cables and eliminate the energy generation during operation.
• Connect the positive cables to the Y-splitters; you will need 2 splitters. If there are 3 panels, you’ll need a splitter with 3 inputs.
• Do the same for the negative cables.
• Connect the system to the charge controller. Wiring solar panels in the parallel diagram is completed.

How To Set up a Series-parallel System

This connection method is rarely used for home batteries; it is more common for systems with many panels covering a large area.The principle of the connection is the following:

• The batteries are connected in pairs in series, i.e., a negative cable to a positive one. 
• These two pairs are connected in parallel. 

That’s how 4 solar panels are connected in series-parallel.

It is generally accepted that all the disadvantages are typical for parallel connections, and the serial connection mainly provides advantages. 

In fact, solar panel connections are better than parallel for large systems but worse than series. With a parallel-series connection, both voltage and current increase.

Wrapping Up

It is extremely difficult to independently calculate which connection will be optimal for connecting panels for your home. There is a fairly accurate calculator that makes it possible to determine the best option: wiring solar panels in series vs. parallel. But it is even better to entrust this matter to a professional.

Specialists consider many different parameters – these are the type of panels, amperage, and voltage, as well as the house’s location, the lighting intensity, and the shading of one, several, or all panels.

The fairly strict criteria can ultimately dictate the choice between solar panel series and parallel. In some cases, you can connect solar panels in parallel, and in others, only in series so that the whole system is efficient and meets the expectations of its owners

There’s no denying that solar energy is the future and will soon replace other power sources. But all new technologies need to be approached wisely. Experts highly advise against buying and installing solar panel wiring series or parallel on your own.

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Jed Hilton

Jed Hilton, our Founder and CEO, has over a decade of experience in the solar industry. His innovative leadership and expertise in solar technologies guide our company's vision and strategy.

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