Should You Use Bifacial Solar Panels?

Bifacial solar panels are among the oldest solar technologies dating back to the 1960s and 1970s. But the development of Passivated Emitter Rear Cell technology helped increase their efficiency.

They have an efficiency of between 20% to 40% as they can collect sunlight reflecting from the ground. That's not all. They do well in cloudy and snowy conditions.

In this article, we focus on bifacial solar panels, how they work, and much more.

What Are Bifacial Solar Panels?

Bifacial solar panels are a type of photovoltaic panel that can generate electricity from both sides, as they have solar cells on both the front and back sides.

These panels can capture sunlight that reflects off the ground, snow, or nearby surfaces, increasing their energy output compared to traditional solar panels.

The front side of bifacial panels typically has an anti-reflective coating to increase the amount of sunlight it can absorb, while the backside may have a reflective coating or be left uncoated to allow for maximum sunlight absorption from the rear.

Bifacial panels can also come in various designs, including glass-glass and glass-backsheet configurations.

Bifacial solar panels are becoming increasingly popular due to their higher energy output, especially in areas with a lot of snow, highly reflective surfaces, or where there are limited spaces for solar installations.

However, they tend to be more expensive than traditional solar panels and require specialized mounting systems that allow for light to reach both sides of the panels.

How Do Bifacial Solar Panels Work?

Bifacial solar panels are a type of photovoltaic panel that can generate electricity from both the front and back sides.

They work by utilizing solar cells on both sides of the panel to capture sunlight that reflects off the ground, nearby surfaces, or even clouds. This makes them more efficient than traditional solar panels, which only generate electricity from the front side of the panel.

When sunlight hits the front side of the bifacial solar panel, the solar cells absorb the light and convert it into electrical energy through the photovoltaic effect.

Meanwhile, the backside of the panel captures sunlight that passes through the panel or reflects off nearby surfaces. The backside of the panel may have a reflective coating or be left uncoated to maximize the amount of sunlight that can be absorbed.

To optimize the performance of bifacial panels, they are often mounted on specialized frames that allow light to pass through to the backside of the panel.

These frames can be elevated off the ground, tilted, or arranged in rows to allow for maximum exposure to reflected sunlight.

In addition, the front side of the bifacial panel is designed to have an anti-reflective coating that reduces the amount of reflected sunlight and maximizes the amount of direct sunlight absorbed by the solar cells.

This coating can also enhance the panel's durability and reduce the buildup of dirt or debris that may affect its performance.

Overall, the ability of bifacial solar panels to generate electricity from both sides makes them more efficient and effective in a wider range of environments than traditional solar panels.

While they tend to be more expensive and require specialized mounting systems, their higher energy output can make them a cost-effective option in certain situations, especially in areas with highly reflective surfaces, limited space, or a lot of snow.

How to Install Bifacial Solar Panels?

Framed bifacial panels are easier to install, and you can use traditional racking and mounting systems. Most manufacturers include their own clamps for mounting the bifacial solar panels.

The higher you tilt a bifacial module, the more the panel produces. When mounted flush to the rooftop, they block any reflected sunlight from reaching the solar cells' backsides.

To ensure they perform better, install the bifacial modules on flat commercial rooftops and ground. This provides more room for tilt and allows the sunlight to bounce to the rear of the bifacial modules.

The mounting system can affect the performance of bifacial modules. Normally, installers cover racking systems with support rails using a back sheet.

This helps to shade the back rows of the bifacial solar cells. But if you use racking and mounting systems specially formatted for bifacial modules, it takes out the need for backside shading.

Frameless bifacial modules require clamps with rubber guards. This protects the glass. During installation, do not over-tighten the bolts as this will damage the glass.

Here are the different ways of mounting bifacial modules.

Roof

The best roofs for mounting bifacial solar panels are highly reflective and flat. White or silver are among the best surfaces as they have the highest albedo light. Installing bifacial solar panels on the roof lying flat is not recommended.

This defeats the purpose of generating electricity using both sides of the bifacial module.

Roof-mounted bifacial panels should be tilted at an angle corresponding to the latitude. Since bifacial panels are much heavier, make sure the roof can handle their weight.

Ground

Ground-based bifacial solar panels take advantage of the ground's reflectance. This is true if installed over the ground with high albedo.

For example, if installed over white tile, brightly colored gravel, or white sand, it maximizes reflectance.

Bad choices for ground-based bifacial arrays are dark. Such a surface absorbs more light than it reflects. For example, grass, dark-colored grit, and rocks. They minimize albedo light and lower the efficiency of the bifacial solar panel.

If you live in snowy areas, ground-based arrays are best. This is because the snow has a high reflectance, unlike grass.

When snow is covering the ground, bifacial panels will still capture sunlight and generate electricity. This is essential as winter experiences fewer hours of sunlight.

To minimize any potential of shadows and shading, special mounting clamps made for the model are usually provided. These clamps and brackets are thinner and help to minimize the casting of shadows.

To get the maximum power output, you must ensure the right tilt orientation. This differs by latitude.

Horizontal and Vertical Setups

Horizontal setups are ideal for installing bifacial solar panels on the side of a building. They provide partial shade and add aesthetics. During the day, horizontal setups capture sunlight and still collect reflected light from the ground.

They are ideal over a pool, front porch, or deck. In fact, they can serve as a transparent roof on an open walkway or pergola.

Vertical setups are usually installed East to West. This allows the bifacial solar panels to capture sunlight early in the morning and late afternoon.

At midday, these panels capture reflected light off the ground and the surroundings. This setup cannot get direct sunlight, especially when the sun is overhead.

Bifacial solar panels perform better when installed high above the ground. This is because the ground-based setup minimizes shadow. Also, the panel captures more sunlight directly as well as albedo light from the ground.

Monofacial vs Biofacial

The market is currently dominated by monofacial photovoltaic modules. However, in the next 10 years, it's predicted that bifacial solar modules will gain 60% of the global market.

This is due to the ability of the bifacial solar panels to generate more power. By 2029, bifacial modules will make up 50% of the market share.

Monofacial modules are not similar to bifacial solar panels. For starters, monofacial PV systems are cost-effective at latitudes below 40 degrees.

Bifacial modules are more cost-effective at latitudes over 40 degrees. They also generate 12% more energy at latitudes below 65 degrees and up to 71% more energy above 65 degrees.

Monofacial solar panels collect sunlight from the top side of the solar cells only. They are usually placed in racks parallel to a surface such as a rooftop. The rooftop does not have to be flat or reflective.

However, to ensure maximum performance of a bifacial solar panel, the roof must be flat and highly reflective. This is because bifacial modules generate electricity from the front and rear sides.

The front side of a bifacial solar cell collects sunlight directly from the Sun. Some of the light passes through and reflects off the ground.

As such, the solar cells on the rear side use albedo light to generate electricity. A 2018 study discovered that bifacial solar systems increase efficiency by 11% compared to other panels.

Installing a bifacial solar panel vertically produces more power than a monofacial panel. A bifacial solar panel takes advantage of direct sunlight and albedo light.

That is why bifacial modules are ideal in snowy areas. They can collect sunlight directly from the Sun and reflective light from the ground, rooftop, snow, or surrounding areas.

Modern bifacial solar panels are using aviation-grade conductors for cell connections. This results in even greater gains. As such, the upgrades amount to about 32% more energy for the next 25 years.

Ground-based bifacial modules generate more power than conventional solar panels. But there is the added cost of having a reflective surface. If installing the bifacial modules on the ground, you have to paint them white or silver.

Alternatively, you can install tiles with a white surface but not grass. You also need a solar tracking system. By painting the ground, installing tiles, and using a solar tracking system, the cost increases.

Bifacial solar panels are more expensive than conventional monofacial panels. The price difference between bifacial and monofacial ranges from $0.01 to $0.10 per watt for large-scale projects.

For residential projects, bifacials are more expensive at $0.20 per watt. Installation and cost of equipment are around 5% higher than that of monofacial arrays.

In 2019, bifacial solar panels costs were 56% higher than traditional monofacial modules.

But in the coming years, prices will fall by more than 23% due to improvements in cell and wafer performances as well as advanced layouts.

Best Practices to Optimize your Bifacial Installation

We know solar panels work the best when they are facing the south. However, the sun moves along the day. To increase return on investment and lower the Levelized cost of electricity, follow these recommendations:

Use Single Axis Tracker

Bifacial solar panel installations with single-axis tracking increase electricity yield by 35%. While dual-axis trackers can achieve high energy yield, they are costly and not cost-effective.

A single-axis tracker means it has one axis of rotation. This axis can be vertical, titled, or horizontal. The most common axis of rotation is horizontal.

It’s usually oriented North-South with the bifacial modules facing the East in the morning and West in the afternoon. The tracker can rotate by section or panel while dual-axis trackers rotate on both the X and Y-axis. This makes the panels track the Sun directly.

Thanks to the use of single-axis tracking, bifacial panels outperform monofacial configurations significantly.

High Albedo

Bifacial solar panels generate electricity from the front and rear sides. To generate more energy from the rear side, the environment should have a high albedo.

One of the best options is a white or silver-colored roof. Another is white tile or driveway.

For large-scale projects, desert sand is a good option. Snow and ice also provide a high albedo. That is why bifacial solar panels are popular in snowy areas as they can generate energy from the limited exposure to the Sun.

As such, they can take advantage of albedo light to maximize performance even with little exposure to the Sun.

Tilt

Bifacial solar panels perform at least 10% to 20% better than baseline monofacial panels at a 20-degree tilt angle. They also perform better by an additional 9.5% at a 30-degree tilt angle.

The more you tilt the bifacial panels, the more energy they deliver. That's why you should install bifacial panels on a flat roof or ground where there is more room for tilting.

This allows albedo to bounce to the rear side of the bifacial panels. Since the bifacial panels are usually raised from the surface, there is less chance of overheating.

The supporting structure can affect the performance of the bifacial panels. Do not use mounts with support rails covered with a single facial module's backplate. It will shade the bottom side of the bifacial solar cells.

Location

The efficiency of your bifacial solar panels is usually tied to your latitude. If you live below 65 degrees latitude, your bifacial panels will generate 12% more energy compared to conventional panels. At latitudes 65 degrees and above, they will produce 71% more energy.

This is because such regions have a high albedo light. Regions below latitude 40 degrees have a low albedo light.

With a solar tracking system, you can increase the bifacial panels' productivity by as high as 27%.

The tracking system tilts the solar cells towards the sky as the Sun makes its way across the sky. This system aims for maximum direct exposure by keeping the bifacial panels perpendicular to the Sun.

Weather

Monofacial and bifacial solar panels are usually affected by rainy and cloudy weather. But bifacial modules have the added benefit of having a rear side capable of generating electricity.

The rear side has more surface area allowing the bifacial solar panel to collect energy even in cloudy and rainy weather.

Thanks to this advantage, bifacial modules can pick up the slack during rainy and cloudy weather. They help to maintain the panel's overall power output. This is unlike monofacial panels whose power output gets affected.

Pros of Bifacial Solar Panels

High Energy Yield

Bifacial solar panels are more efficient than monofacial as they use the front and rear sides to generate more power. This increases the overall production efficiency of the system.

In fact, if you live in snowy areas, bifacial panels ensure that you've electricity thanks to the dual sides energy production of the panels.

Durable

The tempered glass on the front and rear sides of the bifacial panel gives the panels a sounding edge in terms of durability. As such, the panels are more resilient towards wind and other elements. The glass also increases the lighting absorbing capacity of the solar cells.

When front solar cells collect sunlight, some of the light passes through thanks to the tempered glass.

Since the bifacial panels are always mounted over a reflective surface, light bounces back to the rear solar cells. They collect the sunlight and generate more power.

Better Low Light Performance

In rainy and cloudy weather, bifacial panels continue to produce electricity. The Sun shines for a few hours during bad weather.

Thanks to the bifacial panels' ability to produce power on the front and rear sides, the batteries continue storing power for use.

Basically, bifacial modules perform better in low light than monofacial panels.

Even in snowy weather, bifacial panels will continue to produce electricity since the snow has a high reflectance.

Angle of Installation

There is no worry about the angle for installation when it comes to bifacial solar panels. They are suitable for horizontal and vertical setups.

If you use a single-axis tracking system, the panels will continue to produce energy as they will follow the Sun as it moves from East to West. If you install dual-axis tracking systems, they are capable of tracking the Sun in multiple directions.

Small Installation Space

If you don't have much space, you can still meet your energy requirements with bifacial solar panels. Whether you choose a horizontal, or vertical set, bifacial modules will enable you to meet your energy goals.

Cons of Bifacial Solar Panels

Slightly More Expensive

Bifacial panels are slightly more expensive than monofacial modules. The cost of equipment and installation is higher than that of monofacial panels. Painting your driveway or ground white or silver also increases the installation costs.

Despite this, bifacial modules are cost-effective as they offer enhanced energy production. Whether it's rainy, cloudy, or snowy, bifacial modules continue to produce energy.

Extremely Heavy

Since bifacial panels are extremely heavy, they require extra care when it comes to handling. Their heavyweight also compromises your roof's strength. Not only that. Mobility is usually limited.

This makes maintenance a bit challenging. Before installation, you need to hire a professional solar expert to assess the structural integrity of your roof.

Are Bifacial Solar Panels Worth It?

Yes, bifacial solar panels are worth every penny. They are more efficient than monofacial panels as they can use both sides to produce more electricity. This increases the overall system production efficiency.

Since both sides of a bifacial panel are usually covered with tempered glass, the panels are more resilient to wind and other elements. As such, the elements will not compromise the general efficiency of the panels and ensure the panels last long.

In bad weather, the production capacity of monofacial panels is always affected. However, things are usually different with bifacial panels. In snowy, rainy, or cloudy weather, bifacial modules continue to work.

While the front side cannot produce energy due to bad weather, the rear side continues to work thanks to albedo light.

If you're looking for the best solar panel for your home or business, look no further than bifacial solar panels.