How To Wire Solar Panels

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Managing one solar panel is easy! You show it some sun, link it to a charge controller, and that’s that instant green power! However, when you’re ready to expand your array to boost your energy yield, things get a little more complicated.

How To Wire Solar Panels


How To Wire Solar Panels In Series

Much like a normal battery, solar panels have a positive and negative pole, each represented by an MC4 cable. Typically speaking, the positive cable will have a female attachment, and the negative cable will have a male attachment. 

To wire your solar panels in series, all you need to do is take the female MC4 cable of one panel and connect it to the male MC4 cable of the other. 

You’ll then be left with a loose female cable at one end of the panel chain, and a loose male cable at the other end of the panel chain. These should be routed into your solar controller using a solar panel extension cable.

If you wanted to add more panels to this series sequence, you’d simply repeat this process.

What Does It Mean To Wire Solar Panels In Series?

The most significant aspect of wiring solar panels in series is that… 

  • The volts of panels in the series combine
  • But the amperage remains the same.

For example, let’s say you have two identical solar panels, each rated for 20 volts and 5 amps. If you wire them in series, the combined voltage of your array would be 40, but the combined amperage would remain 5.

Why Choose Series?

  • MPPT Charge Controller

There are a number of reasons why you may need to wire your panels in series rather than parallel, but perhaps the most important one is to satisfy the solar charge controller. 

Series setups usually use an MPPT controller (Maximum Power Point Tracking), a device designed to handle high voltages, but it doesn’t just manage lots of volts well, it straight-up needs them to function.

So, let’s say your MPPT controller has a volt baseline of 100 volts. Using our hypothetical 20 V, 5 A solar panels from earlier, you’d need to connect at least 5 in series in order for the MPPT to operate.

Put simply, if you plan on using an MPPT charge controller, it’s likely that you’ll need to wire your panels in series.

  • Low Irradiance Performance

Low irradiance occurs when the sun is rising and setting. This half-light can make it difficult for solar panels to reach the minimum voltage requirement of the charge controller. 

However, being that series setups have beefy combined voltages, they’re more capable of meeting these demands than a parallel setup.

  • Easy Transportation of Energy

The lower amperage of series setups doesn’t require any expensive high-gauge cabling to get from A to B. This means that if you’ve got some serious distance to cover to get your solar energy where you need it, a series setup will be much more cost-effective.

Drawbacks of Wiring In Series

  • Impact of Partial Shade

The way a series reacts to shade can be somewhat problematic. If you have four panels, and one of them is veiled by partial shade, the output of all neighboring panels will plummet to that of this individual troublemaker, even if they’re in direct sunlight.

This is irritating, as a single shadow on a single panel can ruin the effort of your whole array.

How To Wire Solar Panels In Parallel

To wire your solar panels in parallel, instead of connecting positive and negative MC4 cables, you need to connect positive to positive, and negative to negative, using MC4 parallel adapters.

Repeat this process with however many panels you need to, then, take the final parallel adapter and hook it up to your charge controller, and that’s all there is to it! 

What Does It Mean To Wire Solar Panels In Parallel?

Solar panels wired in parallel follow inverse rules to those wired in series:

  • The amperage of each panel will combine
  • While the voltage will remain the same.

So, if you wired two of our 20 V, 5A solar panels in parallel, the voltage of our setup would be 20, but the voltage would be 10 — simple, right?

Why Choose Parallel?

  • PWM Charge Controller

Parallel setups usually use a PWM controller (Pulse Width Modulation) instead of an MPPT. These devices can’t handle tons of volts, but they can shoulder amps like nobody’s business.

Wiring in parallel allows you to connect loads of solar panels without overwhelming a charge controller’s max voltage capacity.

  • Resilience in the Face of Shade

Besides suiting PWM controllers to a tee, parallel setups have one major advantage over series, and that’s their ability to maintain a high output, even if one or more panels in the sequence are in the shade.

In other words, the performance of one panel in a parallel setup is never determined by that of others in the sequence, ensuring you always enjoy an optimal energy yield.

Drawbacks of Wiring In Parallel

  • Voltage Drop

The greater the distance between your solar panels and the charge controller, the more voltage drop you’ll experience.

This isn’t an issue for series connections, as they have a robust voltage to begin with, but for parallel setups, the transitional voltage drop may mean that they’re not meeting the minimum requirements of the PWM controller.

  • Low Irradiance = Low Performance

Parallel systems may not meet controller voltage requirements during sunrise and sunset.

Final Thoughts

As you can see, the actual wiring of your solar panels is pretty simple — you don’t need any extensive solar or electrical experience, nor do you need tons of equipment. The hardest part is determining which format suits your needs the most.

If you’re using a PWM controller or foresee shade being an issue, my advice is to invest in a parallel setup. It may be more expensive due to the adapters and thick cabling required, but you’ll see an epic return on your investment thanks to the efficiency of the system.

In all other circumstances, I’d recommend settling on a series setup and saving yourself some money.