A bifacial solar panel is a double-sided energy factory that transforms sunlight into electrical energy on both its top and bottom sides.
They are different from monofacial solar panels which only use one side for solar energy production. The word bifacial comes from the prefix “bi-” (meaning two), and “facial” (for face).
Bifacials are equipped with solar cells on both the top and the rear of the panel. They are usually monocrystalline, although polycrystalline can be used. Because they are slim, they resemble thin-film panels. Bifacial solar panels are frequently frameless, too.
The top of each solar module is covered in protective glass. The flipside may be glass or a clear backsheet. This is different from conventional solar panel systems with opaque backings.
Here is a diagram of a side view of a bifacial solar panel:
The hardware used to mount a bifacial solar array is designed to minimize shading. This means there are only very narrow support rails and corner-only vertical supports.
The typically backside-placed junction box─the electronic guts and brain of your solar panel system─is smaller than in traditional solar arrays. So, it takes up less space and casts less shade on the back solar cells. The result? More solar power for you.
How does a bifacial solar panel work?
The top solar cells of a bifacial solar panel system face the sun, so they capture incident sun rays directly, absorbing only certain wavelengths. The top solar cells function like those of a conventional solar panel array.
The bottom solar cells absorb light that is reflected off the ground. This light is called albedo light. White or light colors reflect better than dark colors. Painting a white or silver surface on a roof or concrete driveway under the panels provides the same effect, too. Studies show that a white surface reflects more than 80% of albedo light. (Grass, by comparison: 23%).
To optimize the operation of the underside cells, using superior silicon in monocrystalline cells is preferable.
Unlike monofacial solar panel systems that are placed in racks parallel to a surface such as a rooftop, bifacials produce more energy when they are angled off of the roof or ground at varying degrees.