As their name suggests, monofacial solar panels are panels that only work on one side, particularly the side directly exposed to the sun. These are the traditional type of solar panels, commonly used on residential roofs. On the other hand, bifacial solar panels are panels that have solar cells on two sides, the front and the back. This means that both sides capture energy when exposed to light.
The side facing the sun captures sunlight, while the back side – which is not directly exposed to the sun – absorbs light reflected from other surfaces, including water, light-colored roofs, and even snow.
It’s easy to think that the bifacial solar panel is the way to go since you’re essentially getting two panels for the size of one. But there is actually more than what meets the eye. To help you better decide which type is best for you, we’ll review the differences between monofacial and bifacial solar panels in terms of panel design, installation, efficiency, and practicality.
Differences in panel design and installation
At first glance, it can be difficult to distinguish a bifacial solar panel from a monofacial model. After all, both come with standard solar panel lines and look much like any other panel. But upon closer inspection, you will see that they differ in design.
Monofacial panels have a tempered glass front and a typically opaque black or white backsheet. Bifacial panels also have a layer of glass on top, but unlike monofacial models, their back side must be transparent to work. Some models use clear plastic on the back, while others install a layer of glass. This double-glass structure, however, makes bifacial panels heavier than their monofacial counterparts. However, they are generally thinner and, thanks to their often frameless design, fit better visually in many situations.
Since bifacial solar panels are double-sided, their assembly is more complex than the assembly of monofacial panels. For one thing, handaxes should be elevated at least three feet above the ground and tilted at a steeper angle for maximum back exposure. Support rails should also be narrow and junction boxes small. Besides the mounting system, the installation location is also crucial for bifacial solar panels. It is best to install them where reflection is high, such as on light-colored roofs, sand, and snow.
For example, with white sand and gravel, you can get up to 25% more than a monofacial, but on dark roofs, it’s only 5%. The installation of monofacial solar panels is not as strict. As long as the front of the panel is in direct sunlight with minimal shade, you’re pretty much good to go. This means the mounting system can be flexible, especially since monofacial panels are also lighter than bifacial models.
Differences in effectiveness and practicality
Bifacial and monofacial solar panels differ significantly in efficiency and practicality. Since bifacial panels have two functional sides, they are inherently more efficient than monofacial panels. In a 2018 report from solar manufacturer LONGi, bifacial solar panels produced 11% more than their monofacial counterparts when installed on a cement floor and 19.27% ​​on a solar tracking system. In terms of durability against the elements, bifacial panels generally fare better.
Their double-glass design reduces the risk of mechanical damage, wind exposure, and UV degradation. The fact that they can be installed vertically also helps reduce the accumulation of snow and debris on the panels.
But just because bifacial solar panels are more efficient and durable doesn’t mean they’re the better choice. Thanks to their panel design, complex installation, and hardware, bifacial solar panels can cost about 3 to 8 percent more than monofacial panels, or even more. Since they require raised mounting brackets, bifacial solar panels are also not the best choice for most rooftop installations.
Rooftop installation generally means laying the panels flush with the roof, which in turn minimizes light reflection backward and causes the rear cells to function poorly, if at all. You can still use bifacial solar panels for your home, but you need enough space for ground mounting. If you have pergolas or awnings in your yard, they can sometimes serve as mounting brackets, saving space and money.
When it comes to installation, monofacial solar panels perform well whether flush with the roof or mounted on the ground. They also tend to be more affordable for homeowners, allowing you more budget to install solar panel batteries.
