If you’ve ever driven past a building with solar panels lining the roof, chances are, they were single-sided or monofacial solar panels. With this type of PV module, sunlight hits the top face of the panel and then turns that energy into electricity.
But those aren’t the only kinds of solar panels out there. There’s another type—bifacial solar panels. While traditional solar panels have just one side of energy-producing solar cells, bifacial or double-sided solar panels have cells on both sides.
Given their double-sided nature, bifacial panels can generate electricity from both direct sunlight and from the reflected light bouncing back from underneath the panel. Diffused light from clouds, buildings, or other objects can also hit the back and generate electricity.
Bifacial solar panels can produce more electricity with the same number of solar panels. But are they better than monofacial solar panels? In this blog, we’ll take a deeper look into this technology, going over the following topics:
If you’re familiar with how solar panels work, you’ll know that silicon cells capture photons from sunlight and convert them to energy. These cells are held together in a frame, sandwiched between a protective glass coating and an opaque back sheet.
However, when it comes to bifacial solar modules, the opaque back sheet is switched for a clear back sheet. This allows photons from reflected and diffused light to hit the back of the panel and generate power.
To optimize the amount of energy produced by the backside of the panel, shading caused by obstructions like the panels’ racking system needs to be minimized. In a traditional ground mount system, horizontal and vertical support bars are used to support the solar panels.
However, because this traditional racking takes up valuable electricity-producing real estate on the backs of bifacial panels, these systems often have different mounting systems. The support rails across the back are thinner, and there are fewer vertical support poles.
Bifacial panels can generate more electricity than monofacial panels with the same space. If you’re limited on space, opting for bifacial panels can help your system produce more electricity with fewer panels. However, bifacial panels aren’t for every solar-powered home and business. There are a few factors that impact how much your bifacial system will produce.
Bifacial panels installed on tilted roofs are often not ideal because they are flush against the roof, leaving little to no room for light to reach the rear side. As many homes have sloped roofs, bifacial solar panels are not commonly used on residential solar systems. However, if you want to install a ground-mount system, solar carport, or solar pergola, bifacial panels may make sense.
Another critical factor for the success of bifacial panels is the reflectivity or albedo of the surface below the panels. Albedo is how much light is reflected by a surface. An example of something with a high albedo is snow, whereas black asphalt would have a lower albedo.
If you’re considering a ground mount, grass, and soil often have a lower albedo than cool roofs but still offer some reflectivity. To increase the albedo of the land below, you can install high-albedo mats or light-colored stone or gravel.
However, snow is one of the most reflective, naturally occurring materials. If you live in an area that gets a lot of snow, bifacial panels will continue to produce even if the front of your system stays covered.
While solar panels are designed to shed accumulated snow, you will lose out on production while they’re covered. However, with bifacial panels, sunlight reflected off the snow on the ground means your panels will keep generating electricity from the backside as the snow above melts.
The main advantage of bifacial panels is the additional production. While most properly designed bifacial solar systems should produce more electricity than a monofacial system, don’t expect production to double. Because the backside uses reflected energy, it will inevitably produce less than the front side, which receives direct sunlight.
Because there are so many factors, like installation angle and surface albedo, it’s hard to give a solid estimate on how much extra electricity bifacial panels will generate. Most sources say you could see an increase in energy production between 5% and 30%.
Bifacial solar panels typically cost more than traditional monofacial panels. As of summer 2024, bifacial panels cost $0.30 - $0.40 per watt.
But can bifacial panels make up for their extra cost with extra production? If you’re trying to offset your home or business’s electricity, you’ll need fewer solar panels if you go with bifacial and install them in a way that maximizes their efficiency. Your solar installer will help guide you through the decision based on the characteristics of your property and your goals for the project.
Additional Resource: This is the price you can expect to pay for a solar energy installation.
So the question remains—should you install bifacial or monofacial solar panels? To wrap things up, we’ll look at the pros and cons of installing bifacial solar panels and how they compare to their single-sided counterparts.
One of the biggest benefits of bifacial solar panels is producing more solar energy with each panel. So if you’re looking to optimize the amount of electricity you can generate per square foot of space, bifacial panels have the edge.
However, bifacial solar panels have a few disadvantages that could hinder the amount of extra electricity they produce. They can’t be installed as a typical roof-mounted system that’s flat against your roof. There needs to be some space between the backside of the panels and the surface below to reach the reflected light.
In addition, the row spacing between the panels will have to be specifically configured to ensure the shadows the panels cast won’t block light from reaching the underside of the panels. The surface upon which they’re installed should have a high albedo to bring more light to the panels.
So, while monofacial or traditional panels may not be able to produce as much electricity as bifacial solar panels, they still have some advantages. Monofacial panels can be installed as conventional roof mounts or on a surface with low albedo.
Monofacial panels will likely be more affordable and available, as finding a solar company that installs bifacial panels can be tricky in some areas.
That said, both bifacial and monofacial solar panels can be a great investment. Most trusted panel manufacturers offer warranties that last 25 years to 30 years, and the panels could go on producing electricity long after the warranties expire. They'll provide you with a long-lasting way to produce cost-free and emissions-free electricity!
Let our team of solar experts help you select the best panels for your solar investment. Request a quote to get started.
In the meantime, visit our other educational blog post or download our solar buying guide.
Originally posted on 12/23/2019. Updated on 10/13/2021.