Solar Panel Series vs Parallel: Wiring, Differences, and Your Right Choice

In this tutorial, I’ll show you how to wire solar panels in series and how to wire them in parallel.

Once we’ve got that covered, I’ll also explain the difference between these two configurations in Voltage (Volts) and Current (Amps) and provide a real-life example.

Finally, I’ll discuss the pros and cons of each configuration to help you figure out which one fits your needs best.

Let’s dive in.

Solar panels series vs parallel

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How to wire solar panels in series and in parallel?

Every solar panel typically comes with a female and a male MC4 connector. Usually, the female MC4 connector stands for the negative terminal, and the male MC4 connector represents the positive terminal of the solar panel. However, keep in mind that this standard isn’t always consistent.

Regardless, the first crucial step before making any connections is identifying the positive and negative wires of your solar panels.

You can usually find polarity indicators somewhere on the solar panel itself. Look for a “+” sign, which indicates the positive wire, and a “-” sign for the negative wire.

These polarity markers can be located on the junction box, the wires, or the MC4 connectors.

solar panel series vs parallel

If the manufacturer hasn’t clearly labeled the polarity of the solar panel, another approach is to use a multimeter to measure voltage.

solar panel series vs parallel

To do this, insert one multimeter probe into each of the MC4 terminals.

If the reading shows a positive voltage value, it means the positive (red) probe is connected to the positive end of the solar panel. If the voltage value is negative, then the red probe is connected to the negative end of the panel.

For instance, in the image above, you can observe the red probe inserted into the male MC4 connector of the solar panel, signifying the positive terminal. As a result, my multimeter displays a positive voltage reading.

After identifying the positive and negative wires of your solar panels, be sure to mark them before proceeding.

Now, let’s kick off with the series configuration.

How to wire solar panels in series?

To wire your solar panels in series, simply link the positive MC4 connector of the first solar panel to the negative MC4 connector of the next one, and continue this pattern for the remaining panels.

Once you’re finished, you’ll have two unconnected terminals at each end of your series—a positive and a negative. These can be connected to the solar charge controller using extension cables.

The great thing about connecting solar panels in series is that you won’t need any extra components; all you require are your solar panels and a pair of extension cables to link the solar string to the solar charge controller.

solar panel series vs parallel

Each of these extension cables comes with an MC4 connector on one end, which attaches to the solar panels, and a stripped end that connects to one of the terminals on the solar charge controller.

solar panels series vs parallel

As an illustration, for this tutorial, I’ve connected the positive MC4 connector of the left panel to the negative MC4 connector of the right panel since I’m working with only two solar panels.

solar panel series vs parallel

And voila! we have a string of 2 solar panels:

solar panel series vs parallel

To hook up the solar panels to the solar charge controller, I simply used the extension cables. I connected the negative end of the string (on the left) to the negative terminal of the SCC and linked the positive end of the string (on the right) to the positive terminal of the charge controller.

How to wire solar panels in parallel?

To wire solar panels in parallel, you’ll require a couple of branch connectors. These connectors link all the positive terminals of the solar panels, creating the positive terminal of the solar array, and they connect all the negative terminals to form the negative terminal of the solar array.

In addition to your solar panels and extension cables, you’ll need two extra components:

  1. A pair of MC4 Y branch connectors.
  2. MC4 inline fuses, if necessary.

solar panel series vs parallel

In the image above, you can see a pair of 2-to-1 (or Y) MC4 branch connectors, since I’m only connecting two solar panels in parallel. However, if you have more solar panels, you’ll require branch connectors with a matching number of inputs.

For instance, if you have three solar panels, you’ll need a pair of 3-to-1 MC4 branch connectors. To wire four solar panels in parallel, use a pair of 4-to-1 MC4 branch connectors.

Now, to wire my two solar panels in parallel, the initial step was connecting the fuses to the positive leads of the solar panels.

solar panel series vs parallel

Read more about fusing solar panels.

After fusing the solar panels, I joined the positive wires using a Female-Female-Male MC4 branch connector and connected the negative wires using a Male-Male-Female MC4 branch connector.

solar panel series vs parallel

The wire on the left represents the negative end of the solar array. Using the extension cables, it should be connected to the negative PV terminal of the solar charge controller. The wire on the right is the positive wire, which needs to be connected to the positive PV terminal of the charge controller.

Solar Panels Series vs Parallel: What Is The Difference?

Whether you connect solar panels in series or in parallel, the total power output (in Watts) is the sum of the power generated by each solar panel. The difference between these two types of configurations is the total Voltage (Volts) and the total Current (Amps) of the solar array.

When you wire solar panels in series, you raise the Voltage of the system, while the Current stays the same.

solar panel series vs parallel

Voltage:

Total Voltage (Volts) = Voltage 1 + Voltage 2 + Voltage 3 + Voltage 4

Total Voc (Open-Circuit Voltage) = Voc 1 + Voc 2 + Voc 3 + Voc 4

Total Vmp (Maximum Power Voltage) = Vmp 1 + Vmp 2 + Vmp 3 + Vmp 4

Current:

Total Current (Amps) = Current 1 = Current 2 = Current 3 = Current 4

Total Isc (Short-Circuit Current) = Isc 1 = Isc 2 = Isc 3 = Isc 4

Total Imp (Maximum Power Current) = Imp 1 = Imp 2 = Imp 3 = Imp 4

When you wire solar panels in parallel, you raise the Current of the system, while the Voltage stays the same.

solar panel series vs parallel

Voltage:

Total Voltage (Volts) = Voltage 1 = Voltage 2 = Voltage 3 = Voltage 4

Total Voc (Open-Circuit Voltage) = Voc 1 = Voc 2 = Voc 3 = Voc 4

Total Vmp (Maximum Power Voltage) = Vmp 1 = Vmp 2 = Vmp 3 = Vmp 4

Current:

Total Current (Amps) = Current 1 + Current 2 + Current 3 + Current 4

Total Isc (Short-Circuit Current) = Isc 1 + Isc 2 + Isc 3 + Isc 4

Total Imp (Maximum Power Current) = Imp 1 + Imp 2 + Imp 3 + Imp 4

As an illustration, I’ll connect two identical 100W solar panels both in series and in parallel, and demonstrate the resulting voltage and current.

Here are the electrical specifications for each of these solar panels:

Solar panel series vs parallel

Let’s start with a series connection.

Solar panels in series:

solar panels series vs parallel

As previously explained, in a series connection, Voltage increases while Current remains the same. Therefore, with these series-connected solar panels, we now have a solar string with the following specifications:

  • Rated Power = 100 Watts + 100 Watts = 200 Watts
  • Max. Power Current = 5.62 Amps
  • Max. Power Voltage = 17.8 Volts + 17.8 Volts = 35.6 Volts
  • Short Circuit Current = 6.23 Amps
  • Open-Circuit Voltage = 22.5 Volts + 22.5 Volts = 45 Volts

However, the actual Voltage and Current that the string produces at a given moment will depend on the amount of sunlight available for the solar panels to convert into electricity and the type of solar charge controller you’re using.

In my case, I’m using an EPEVER MPPT charge controller. But as you can see in the image above, it was cloudy, and the solar panels were not receiving direct sunlight.

Solar panel series vs parallel

As a result, the string was only generating approximately 25 Watts of power instead of the full 200 Watts:

Power (Watts) = Voltage (Volts) x Current (Amps)

Power (Watts) = 42 Volts x 0.6 Amps

Power (Watts) = 25.2 Watts

Now, let’s explore how voltage and current differ in a parallel connection.

Solar panels in parallel:

solar panel series vs parallel

As previously mentioned, in a parallel connection, the Current increases while the Voltage stays the same. With this setup, we now have a solar array with the following specifications:

  • Rated Power = 100 Watts + 100 Watts = 200 Watts
  • Max. Power Current = 5.62 Amps + 5.62 Amps = 11.24 Amps
  • Max. Power Voltage = 17.8 Volts
  • Short Circuit Current = 6.23 Amps + 6.23 Amps = 12.64 Amps
  • Open-Circuit Voltage = 22.5 Volts

In this second test, the solar panels received more sunlight, although it still wasn’t optimal:

solar panel series vs parallel

At 21 Volts, our parallel-connected solar panels were producing only 1.6 Amps, which amounts to 33.6 Watts:

Power (Watts) = Voltage (Volts) x Current (Amps)

Power (Watts) = 21 Volts x 1.6 Amps

Power (Watts) = 33.6 Watts

While the parallel connection in my test seems to yield more power, this is because the solar panels received a bit more sunlight. It’s important to note that a parallel configuration doesn’t always result in more power.

Each configuration has its own set of pros and cons, and your choice between them will depend on the specific requirements and limitations of your solar system.

Let me explain.

Solar Panels Series vs Parallel: Pros and Cons

Connecting solar panels in series:

Pros:

  • Simplicity and Cost: It’s easier and more cost-effective to connect solar panels in series. No additional parts are needed, which simplifies the arrangement and lowers expenses.
  • Reduced Current: Series connections mean less current flowing through the wires, allowing for the use of thinner and more affordable wires, and eliminating the need for fuses.

Cons:

  • Charge Controller Requirement: When you wire solar panels in series, you’ll often need to use an MPPT solar charge controller. Using a PWM charge controller can make the solar panels susceptible to shading and mixed lighting conditions.
  • Cost: MPPT charge controllers are a better technology and are typically recommended for higher system efficiency, but they are more expensive. This may not always be cost-effective, especially for small solar systems.

So, when to opt for a series configuration?

1- If you’re using an MPPT solar charge controller:

MPPT (Maximum Power Point Tracking) charge controllers have a valuable capability: they can decrease the voltage from the solar array while simultaneously increasing current at their output by the same ratio. This allows you to maintain a series configuration with a higher voltage without sacrificing power.

MPPT charge controllers also enable you to wire your solar panels in series because they can activate the bypass diodes within the solar panels if one of the panels receives less sunlight than the others, such as in cases of partial shading or mixed lighting conditions.

Learn more about solar panel shading.

Just be cautious to ensure that the maximum voltage from your solar array doesn’t exceed the input voltage tolerance of your MPPT charge controller.

Related: Make use of our MPPT calculator.

2- If you have mixed solar panels with similar amperage ratings:

When you have solar panels from different manufacturers with varying voltage and amperage ratings, it’s important to consider the implications:

As previously explained, in a series connection, the voltages from the panels add up while the current remains the same. With mixed solar panels, if the voltage and amperage ratings are not identical, the voltages still add up, but the current will be equal to the lowest current rating in the string.

However, if you have mixed solar panels with different voltage ratings but relatively close current ratings, it can still make sense to wire them in series. This can help you make the most of the available power output while managing variations in voltage ratings.

3- If you have long wire runs:

When determining the wire size between the solar panels and the charge controller, two key factors come into play:

  1. Current Load: The amount of current flowing through the wire. Higher current requires thicker wires to handle the load.
  2. Voltage Drop: The distance between the solar panels and the solar charge controller impacts the wire thickness required to mitigate voltage losses.

Wiring your solar panels in series allows for the use of smaller gauge wires. This is because the current is relatively low, and the higher system voltage can tolerate a higher voltage drop compared to a lower system voltage.

Connecting solar panels in parallel:

Pros:

  • Cost-Efficiency: Wiring solar panels in parallel allows you to use PWM charge controllers, which are more budget-friendly compared to MPPT charge controllers.
  • Individual Panel Performance: In a parallel connection, each panel operates independently in terms of current production. If one panel is shaded or receives less sunlight, it doesn’t affect the current production of the other panels.

Cons:

  • Higher System Current, Lower Voltage: Parallel wiring leads to higher system current and lower system voltage, necessitating thicker wires to handle the current and limit voltage drop.
  • Additional Components: A parallel configuration requires the use of extra components like branch connectors and fuses, which are almost always necessary when wiring solar panels in parallel.

So, when to opt for a parallel configuration?

1- If you’re using a PWM charge controller:

When using a PWM charge controller, you’ll need to make sure that the nominal voltage of the solar array matches that of the battery. For example, if you have two 12V solar panels charging a 12V battery with a PWM, these solar panels would have to be wired in parallel to minimize energy losses.

2- If you have partial shading and variable lighting conditions:

When solar panels are exposed to varying amounts of sunlight due to partial shading or facing different directions, parallel wiring reduces system losses.

Each solar panel operates independently, meaning one panel’s reduced output doesn’t impact the output of the others.

2- If you have mixed solar panels with similar voltage ratings:

When dealing with mixed solar panels that share the same nominal voltage (e.g., 12V) but have different current ratings, you can still wire them in parallel.

The total current of the array will be the sum of the currents from each panel, and the voltage of the array will match the lowest voltage rating in the array.

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Younes Anas EL IDRISSI

Younes Anas EL IDRISSI is the founder of RenewableWise.com and the driving force behind it. As a former Electrical Engineer and an energy self-sufficiency enthusiast, Younes' mission is to leverage his expertise and experience to simplify the complexities of solar energy and make it easily understandable for anyone looking into DIY energy solutions. Learn more about Younes and the story of RenewableWise here.

17 Comments

  1. You talk about panel output, volts & amps. My question is about the voc voltage, how does that change in series & parallel circuits?

  2. whats the best way to wire solar so you can get the maximum out put . i read that in series if the cloud comes over and blocks the first panel you have stuff all power it seems more like every cell has a tap and water flows through all the panels and if a tap is turned off then no water flows to the rest restricting out put . in parallel the out put is not to restricted ? .so is a series parallel system the best way to wire panels or does voltage output come into it and what is the minimum voltage the control unit need

  3. Hi
    I have a canal boat with six x 350wat solar panels, and four 12v 300amp lithium batteries. These are connected in a 24v circuit. My BMS shows a 28.40v for all four batteries, but the capacity has gone down from 100% to 35% in the last few weeks with very little use. How can this be with fully charged batteries ?.
    Kind regards Alan

    • Hey there Alan,
      Please define “very little use”?
      If, in the last few weeks, your solar panels have been getting suboptimal sunlight, and your batteries are sized just enough to offset your daily energy consumption, this seems normal.
      So, how much energy (in Watt-hours or kiloWatt-hours) do you usually use on a daily basis?
      Also, how many Peak Sun Hours do you get?

  4. What happens if 2 panels are connected in series and then connected to one panel in parallel? All panels have the same specs.

    • Hello there,
      In such a case, the single solar panel will likely be act as a short-circuit due to its bypass diodes. If an MPPT is used, the bypass diodes will not work, and the single panel will end up lowering the combined voltage of the other two panels, which means you’ll have the same power output as if you only had 2 panels in parallel.
      This is not advised.
      Hope this helps.

  5. Hi
    I just purchased an Anker SOLIX F2000 Solar Generator with a 400w portable solar panel. The specs show the following:
    Open Circuit Voltage 48.5V
    Power Voltage (Vmp) 39V
    Power Current (Imp) 10.25A
    I want to put 3 additional panels I already have (Unisolar Model Type US-64) in series together, then in parallel with the Anker panels. The specs I have on this are:
    Open Circuit Voltage 23.8V
    Voltage Max Power 16.5V
    Current Max Power 3.88
    Max Power 64W
    Is this a workable way to maximize my input to the solar generator?
    What numbers could I reasonably expect?
    Any advice?

    Thanks so much for your input- I appreciate it.

    Tim

    • Hi tim, after running the numbers I suggest you wire the 3 identical solar panels in parallel, and then wire that array in series with you 400W solar panel.
      The setup you suggest would also work but you would end up losing about 40 Watts. The 2nd configuration will minimize those losses to about 23 Watts.
      I hope this helps.

      • Hi Younes,
        Thanks for your response- it demonstrates why you’re the engineer and I’m not! So doing as you suggest, what would you estimate my Power Voltage (Vmp) and Power Current (Imp) to be, and would you anticipate any issues with a 60V max input to my Anker SOLIX F2000 Solar Generator?

  6. I have a partially shaded lot at certain hours. I have 4 400 watt panels for my Ecoflow delta pro. Should I wire in series due to the shading?

    • Hello Julian,
      Well, the Ecoflow Delta PRO has a built-in MPPT charge controller. So, in the case of partial shading, the MPPT should be able to activate the bypass diodes inside your solar panels. So to answer your question, Yes, a series connection is probably the right move.

  7. Hi Tim
    I got two panels of 400 watts having capacity of 40 volts and 10 amperes while got three panels of 575 watts having capacity of 42.6 volts and 13.5 amperes.
    Kindly advise how I can get max output. I got mppt controller that can operate even at 30 volts.

    • I believe the most obvious solution here is to wire everything in parallel, so you’ll end up with an array of 5 solar panels in parallel. With this configuration you’ll only lose about 100 Watts of power. But this means you’ll need thicker wires between the junction and the charge controller…

  8. I have a 40A MPPT controller. I am about to buy a 525W panel for an area that will be shaded. I’m wondering if I should use one panel or multiple panels in an what array for best results?

    • It really depends on the shading situation. A single solar panel will have bypass diodes so if it’s partially shaded vertically, the bypass diodes should be able to disconnect the shaded area, This is assuming the bypass diodes are operational.
      But if it’s partially shaded horizontally, it would be similar to being completely shaded. Of course, if it’s completely shaded in the first place, that bad.
      In general, it is better to used multiple solar panels wired in parallel, and place them in a way that if it’s partial shading, it would only hit some of the panels.
      Again this depends on the situation.
      Hope this helps.

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