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Can you Mix Mono and Poly Solar Panels? The Detailed Guide

A combination of monocrystalline and polycrystalline solar panels will work fine if there’re no considerable differences in their electrical characteristics. It’s advisable to wire mono and poly solar panels in distinct strings for maximum output.

According to the mismatch rule, the voltage and short circuit current difference of the two types of solar panels should be less or equal to 25% to allow for mixing without power loss.



Combining monocrystalline and polycrystalline for improved performance requires a strategy and that’s exactly what we’ll discuss in this guide.

If you’re entirely new to the solar power scope and are wondering how to choose between poly and mono solar panels, this post is also for you.

It’s ‘OKAY’ to Mix Mono and Poly Solar Panels.

Generally, when connecting solar panels, you’ll do it in strings. Each string has several solar panels and should be connected to a Maximum Power Point Tracker (MPPT), for output monitoring.

Every inverter has an operating range (the input range) which it’ll best operate at. Additionally, it’ll have a maximum power point which will be the maximum net power it’ll work with without damage.

More on this later, but here is how these ratings relate to our topic:

If you combine mono and poly in the same string, there’s a high possibility that the output will be lower than the inverter’s operating range due to electrical characteristic differences.

When there’s insufficient power going into the inverter, it’ll not power on, and you’ll not get the juice you need to power up your devices.

However, combining monocrystalline and polycrystalline solar panels (each type in a distinct string) gives you the capacity to monitor the output rating, not to mention that fluctuations will barely occur.

In this case, the inverter will operate as intended and you’ll have the power you need from your system.

However, this is still a generalization, but we’ll have a practical example later to show you how you should go about the mix and match process of mono and poly solar panels.

Before we jump into the process, let’s first understand what mono and poly solar panels are.

What are Mono Solar Panels?

Mono or monocrystalline solar panels are an assembly of photovoltaic (PV) cells made from pure silicon. Monocrystalline cells are squares with no corners. This leaves small white spaces between the individual cells.

To make mono solar panels, silicon is first made into bars, then cut into wafers (a small piece of crystalline silicon). This leaves only one silicon crystal in the entire solar panel.

Monocrystalline solar panels are the oldest solar panels, meaning they’ve been refined significantly over the years. They’re also the most common solar panels in the market.

What are Poly Solar Panels?

A polycrystalline solar panel is a collection of PV cells made from silicon fragments. Polycrystalline cells, like monocrystalline panels, are square, but there are no spaces in the corners.

To produce poly solar panels, silicon fragments are melted, cooled, and allowed to form wafers.

Polycrystalline solar panels have not been in the industry for long but are already gaining popularity and receiving a good deal of refining.

Poly solar panels are also called multi-crystalline solar panels.

How to mix mono and poly solar panels?

Step -1:

Determine the number of mono and poly solar panels (based on their electrical characteristics) your inverter will work best. A qualified solar technician should do this task for you.

Step -2:

Choose mono solar panels of similar electrical characteristics (voltage and current) and wire them to form a string.

Step -3:

Do the same for the poly solar panels you have.

Step -4:

If there’s still a need to mix the solar panels in a single string, here’s how to check for a mismatch:

Take the current/ voltage rating of the lowest rated panel, divide by the current/voltage rating of the highest rated panels, and then subtract the answer from Step -1.

The final figure should not be greater than 0.25 or 25% for compatible mixing to be achieved.

Let’s take current as the target electrical rating and check for mismatch in these two configurations.

Configuration 1:

The solar panel with the highest rating is 8.0A while the lowest is 3.0A

⅜ = 0.375

1- 0.375 = 0.625

The final figure is greater than 0.25; hence these solar panels will lead to power loss if wired in the same string. Even if these are both mono or both poly solar panels, they should not be wired in the same string.

Configuration 2:

Maximum current rating 8.0, lowest current rating 6.4

6.4/8.0 = 0.8

1- 0.8 = 0.2

The final figure is below 0.25; hence the panels can be combined in the same string even if they’re a mix of mono and poly solar panels.

Step -5:

The final step is to connect each string to a charge controller of a string inverter.

You can tell that the big question here is not if you can mix mono and poly solar panels of the same characteristics. It’s whether the electrical characteristics of the solar panels allow for mixing.

Tips to Consider When Combining Mono and Poly Solar Panels

1. Go for the correct configuration of the solar panels.

There’re two main wiring configurations for solar panels: series and parallel wiring.

  • Mono and Poly solar panels in series- If you connect mono and poly solar panels in series, the current of all the panels should be the same. If otherwise (one solar panel has a very low current rating), the output current that goes to the inverter will be limited to the current of the lowest-rated panel.
  • Mono and poly solar panels in parallel- In parallel, the voltage rating of the mono and poly solar panels should be the same or close to similar for maximum output to go to the inverter.

In either connection, ensure that you use high-quality wires and connectors so that there’s no power loss. For more details on this, check out our post on wiring solar panels in parallel or series.

2. Use a MPPT charge controller for each string

A maximum power point tracker helps monitor the output difference of the two types of solar panels if they’re wired on different strings. Use an MTTP charge controller for each string to be on the safer side.

The good thing is, some modern string inverters come integrated with multiple MPPTs, so you don’t have to buy them separately.

3. Wire mono solar panels in one string and poly panels on another

As a general rule, avoid mixing mono and poly solar panels in the same string to prevent output losses due to differences in electrical parameters.

Please note that, in this, we assume that all the mono solar panels have similar electrical parameters, the same as all your poly solar panels.

The Best Mono/Poly Strings Mixing Ratio

The maximum power ratio

If you’re looking to harness more power from the system, you should have more mono solar panel strings than poly solar panels strings. This ratio will also save on roof space since you’ll use fewer solar panels.

The low-cost ratio

If the amount of power the system produces is not a significant concern, it’s okay to have more multicrystalline strings than monocrystalline strings. Be ready to have enough roof space for this ratio.

Difference between Monocrystalline and Polycrystalline Solar Panels

Hope that the mixing criterion of mono and poly solar panels is now clear. But what if you’re just getting started with your solar power project?

What solar panels should you acquire? What are the factors to consider when choosing mono and poly solar panels?

Let’s compare mono and poly solar panels under various factors so that you can better understand them.

Price

The average cost of mono solar panels average at $0.6-$0.9 per watt

Poly solar panels cost around $0.4-$0.6 per watt

Tip: From a consumer standpoint, the price difference between mono and poly solar panels is negligible nowadays, so the price will barely be your deal-breaker.

All in all, check the financial implication of buying, installing, and maintaining mono and poly solar panels and settle for a ratio that won’t hurt your budget.

Efficiency

Due to the single crystalline form of monocrystalline solar panels, the flow of electrons in the cells of a monocrystalline solar panel is a breeze, leading to high efficiency (usually 15-20% ).

Polycrystalline solar panels have a more cramped cell structure, limiting electrons’ flow. In this regard, they tend to have low efficiency (13-16%)

Tip: Before you rule out poly solar panels for their lower efficiency, check their ratings. Any solar panel with around 15% efficiency is a good choice.

Lifespan

Monocrystalline solar panels last for around 30-40 years.

Polycrystalline solar panels can serve you for around 30-35 years.

Tip: There’s no significant difference between the lifespan of the two solar panels. How long they’ll serve you will depend on how you’ll maintain them.

Size and weight

Monocrystalline standard sizes are 60-cell and 72-cell.

Here are the standard dimensions, cell arrangements, and weight of these two sizes of solar panels:

Solar panel sizeinchesftcmKgsPoundsCell arrangement
60-cell panels39 X 663.25 X 5.599 X 16716- 2235-486 X 10
72-cell panels39 X 773.25 X 6.4299 X 19522-2848-616 X 12

Multicrystalline standard sizes are also 60 and 72-cell configurations with the same cell arrangements and dimensions shown in the table above.

Tip: Size goes hand in hand with efficiency, so monocrystalline solar panels will perform better than multicrystalline solar panels of the same size.

Wondering what solar panel size between 60-cell and 72-cell is right for you? Check out our detailed guide on this.

Low light performance

On account of their high efficiency, mono solar panels perform better in low light conditions.

Poly solar panels have an average performance in low light conditions.

Takeaway: These two types of solar panels are complimentary. Mono solar panels will boost the system’s output when there’s insufficient sun, while poly solar panels improve the system’s output when there’s plenty of light.

Appearance

Mono solar panels have a solid black hue and generally look sleek but subtle on the roof. Due to how the cells are shaped, the panel may sometimes have white spaces.

The good thing is, manufacturers have a way to get around this, and it’s not a major issue anymore.

Poly solar panels are pretty off, aesthetically. Each cell has a blue hue and looks different from the adjacent cells. This is a result of how the sun reflects off differently from each PV cell.

Tip: If you’re more concerned with aesthetics, mono solar panels should work just fine for you. It’s worth noting that the appearance features of solar panels have the potential to impact their performance and price, so don’t go overboard on this factor.

Bonus summary tip: When deciding between mono and poly solar panels, look at the individual specs of the panels, as obviously, there’re differences even between a single type of solar panels.

Which is better? Mono or Poly Solar Panels?

No hard and fixed rule determines which of these solar panels is better. Instead, it depends on what you’re looking for as a consumer.

Regardless of their size, mono solar panels are highly energy-efficient and are made for homeowners with limited roof space.

Multicrystalline solar panels, on the other hand, have OKAY efficiency and are perfect for homeowners working on a tight budget but have no space constraints.

According to experts, mixing these two types of solar panels in a reasonable ratio can help you strike a balance of the overall benefits of each type.

Pros and Cons of Mixing Mono and Poly Solar Panels

Pros

You enjoy the benefits of both types of solar panels.

You don’t have to acquire expensive solar panels to meet your energy needs.

Cons

Possible output power loss if incompatible solar panels are wired together.

Many considerations go into determining the mixing compatibility, so installation can be time-consuming.

Wrapping up

While it’s recommended to use solar panels of the same electrical characteristics, you can mix mono and poly solar panels, following some guidelines.

If you want to mix mono and poly solar panels, do it in different strings and ensure each has its own MTTP charge controller.

You can still do mono and poly solar panels in one string, but check for mixing compatibility through the methods shown in this guide.

Mixing mono and poly solar panels can increase the overall performance of the system when done right.