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A Comprehensive Guide to Bifacial Solar Panels

Featured image for bifacial solar panel article

A great thing about solar panels is that they keep working all day. It doesn’t matter if the sun’s just risen, or just about to set — your panels will pick whatever light is reflected from the atmosphere or the ground. They even work when it’s cloudy.

But what would you say if I tell you there are solar panels that pick up sunlight from the underside too and deliver up to 30% more energy?

Bifacial solar panels use the technology of active solar cells on both sides, so they can pick the solar energy that is “coming” from below.

What Are Bifacial Solar Panels?

Bifacial solar panels are double-sided panels that use both the top and bottom sides to capture and transform the solar energy.

They’ve been around since they were first used in the Soviet space program in the 1970s but they were too expensive to produce for utility-scale projects.

what is a bifacial solar panel

Lumos Solar GSX bifacial modules

The good news is it’s much cheaper to manufacture them now, which means that ordinary people like you can already have access to them.

Bifacial panels are often much slimmer than their monofacial counterparts and often frameless. The top of each panel is covered with protective glass, while the flipside is either glass or a clear back sheet.

Why Use Bifacial Solar Panels?

Bifacial solar panels have many advantages to traditional single-sided panels.

For example, they are great if you are short on space. They offer more solar energy for the same solar panel size and for only a bit higher installation costs.

Bifacial solar systems are more effective at latitudes beyond 40°. At latitudes beyond 65°, bifacials can reach a whopping 71% increase in energy production.

As they are designed to collect sunlight from both sides, bifacial modules are typically raised from the surface. This means that there’s less chance of them overheating.

Another great thing is they’re also often more durable because both of their sides are UV-resistant.

For you, perhaps the most interesting benefit is that you can install bifacial panels in many different configurations. They can be tilted at different angles and used successfully as ground mounts or as raised mounts on flat roofs.

solar pergola

A 6.5 kW Solar Pergola Installation (Source: CED Greentech)

This means you can use bifacial panels for both commercial and residential sites.

Finally, since they are transparent and relatively slim, bifacial panels can be beautifully integrated into various aesthetic and architectural elements such as canopies, pergolas, and sun-breakers.

How Does A Bifacial Module Work?

The top solar cells of a bifacial solar panel face the sun so they can absorb the available sun rays directly. In this sense, it’s no different than a conventional solar panel.

The bottom cells, however, are designed to absorb reflected light. This means that unlike conventional one-sided panels, bifacial panels produce more energy when you angle them to a white roof or to the ground. [1]

Even more amazing, since bifacial panels are all about light reflection, they are even more productive on cloudy days when the light is already diffused.

You can take advantage of this and tilt half of your panels facing east and the second half facing west. This way you’re covered for the whole day, as your panels capture both morning rays and the afternoon peak.

two faced solar modules tilted at an angle

Source: Trace Software International

At the same time, the panels’ backsides are doing their part by soaking the solar energy that “comes” from the other side.

You can also place your bifacials vertically. This setup also gives you two energy peaks each day and during each bleak, while the rear side harvests the reflected light.

How Are Bifacial Solar Panels Installed?

Bifacial solar panels are installed depending on their type. You can install a framed bifacial solar panel much easier than a frameless one, just because traditional solar modules are already adapted for framed models.

installation

On the other hand, most bifacial panel manufacturers include their own clamps to mount their products, so the installation becomes pretty much straightforward.

As frameless solar panel models are concerned, the clamps often come with rubber guards that protect the glass.

When installing this type of panel, installers must take care not to over tighten the bolts and damage the glass.

The more a bifacial solar panel is tilted, the more energy it delivers. That’s why you should always use them on either a flat rooftop or ground-mounted arrays which offer a lot of room for tilting and for the reflected light to bounce to the rear end of the module.

As they are designed to collect sunlight from both sides, bifacial modules are typically raised from the surface. This means that there’s less chance of them overheating.

Finally, you need to know that the supporting structure can affect the performance of your bifacial panels.

Mounts with support rails that are covered by a single-facial module’s backplate will shade the bottom-side bifacial cells.

This is why you should go with mounting and racking systems that are especially designed for bifacial installation.

How Much Do Bifacial Solar Panels Cost?

Bifacial solar panels cost a little more than traditional single-sided panels. In a 2019 study by NREL (National Renewable Energy Laboratory), you can see that the cost difference between monofacial and bifacial panels goes between $0.01 to $0.05 per watt for larger utility-scale projects. [2]

For smaller commercial or residential projects, on the other hand, bifacials are going to be more expensive at $0.20 per watt.

Bifacial vs Monofacial: How Efficient Are Bifacial Solar Panels?

The efficiency of solar panels is the capability of a solar cell to convert the total amount of solar energy into electrical energy.

In a 2018 study by LONGi Solar, it was discovered that bifacial solar systems can increase the efficiency by 11% of that of traditional solar panels.

The latest generation of SunPower Performance bifacial panels uses aviation-grade conductors for cell connections, resulting in even greater gains while maximizing the active area. These engineering upgrades amount to about 32% more energy over 25 years.

But can their efficiency be increased even more?

Yes, you can increase their productivity by as high as 27% if you go with a solar tracking system that keeps tilting solar cells toward the sun as it makes its way across the sky.

Such a system is constantly aiming for the maximum direct exposure by keeping the panels perpendicular to the sun at all times.

two sided solar modules raised from the surface

To achieve the same amount of solar power, you’d need more monofacial panels.

However, the real efficiency of different types of solar panels also depends on your latitude.

Monofacial solar systems are more cost-effective at latitudes below 40° because these regions have low reflected light, or albedo light.

Bifacial solar systems, on the other hand, are more effective at latitudes beyond 40°.

At latitudes beyond 65°, bifacials can reach a whopping 71% increase in energy production.

How to Know if Bifacial Solar Panels are Right for You

roof that is white

To decide whether you can benefit from bifacial solar, you need to consider your site’s surface reflectivity or albedo potential and the available tilt angle first.

Metal roofs and white roofs are great reflectors, so if you have one of these, you should definitely consider bifacials.

If you live in an area with a lot of snow, you should consider a bifacial ground mount, because snow is one of nature’s most reflective materials.

And you know what the best part is? Bifacials will keep producing electricity even when their top side is covered with snow!

The more vertical your bifacial panels are, the more light reaches the backside, and the more energy they can produce. This is why bifacial panels might be the best choice if you have a flat roof or enough room in your backyard for a ground mount.

If you’re still undecided here’s a quick questionnaire. If you answer at least two of these questions with “yes,” then a bifacial system is great for you.

  1. Do you have space for a ground-mount system on your property?
  2. Is there snow cover on your property for most of the year?
  3. Is there a sandy area on your property? (Would you create a mini-desert?)
  4. Would you like to create one or several pergolas or awnings?
  5. Is your roof white or silver or could you paint it or cover it with white or silver shingles?

Bifacial Solar Panel Manufacturers

Manufacturers are constantly looking to implement new technology and design solutions to make bifacials even more effective.

SunPower is one of the most well-known companies in the solar industry. Their new line of bifacial solar panels is protected by more than 144 patents and patent applications.

Their Performance 5 panels offer a conversion efficiency of over 21%. They’re also more tolerant to shade and more durable, meaning you’ll be able to save so much more in the long run compared to others.

performance 5 panels from sunpower

SunPower's Performance 5 panels (Source: SunPower)

And this is where it gets cooler: Their design is reinforced with aviation-grade conductive adhesives.

Why is that cool? Well, just the fact that it’s aviation-grade is already awesome in itself. But also, you want those extra cell connections because they keep your power output high, even if a few of those cells crack.

OK, this all sounds great, but you might be thinking, how much money can these hi-tech bifacial modules actually save me?

Well, I could tell you, but you better hear it from the experts.

Just enter your ZIP code in this SunPower free solar estimator and follow the next few steps to get a free estimate of how much you can save with bifacial modules.

What’s The Future for Bifacial Solar Modules?

Experts agree that bifacial solar modules may really take over the market in the next few years. 

According to the technical director of Chinese solar panel manufacturer LONGi Solar, the new era of solar will favor high-efficiency bifacial modules made with high-end materials.

Although bi-facial systems are slightly more expensive than monoracial modules, the power bonus you’ll be able to get from bifacial modules is more than enough to justify the cost.

The financing community is coming around on bifacial and the cost structure is coming down. We’ll be hearing more about that technology in the coming two or three years.


Vincent Ambrose, Canadian Solar’s General Manager for North America

A 2019 report by Wood Mackenzie Power & Renewables expects the costs of bifacial panels may drop by another 23% in five years.

Keep this in mind if you’re in the market for cheaper green energy.

Conclusion: Are Bifacial Solar Panels Worth It?

Yes, bifacial solar panels are worth it. With solar cells on the rear side as well, they increase the power you can gain by collecting sunlight that reflects from the roof or ground.

You can maximize bifacial modules’ output by installing them on a solar tracking system that keeps them tilted towards the sun all the time.

Another way to increase their productivity is to paint your roof white or use light-colored pavers in case of a ground-mount, as this directly boosts the amount of reflected sunlight.

If you’re considering bifacials, you will want to get a free detailed assessment of your future solar site now from SunPower to check how much money you can actually save with these modules.


References

  1. https://www.osti.gov/pages/servlets/purl/1423188
  2. https://www.nrel.gov/docs/fy19osti/74090.pdf


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