Generate up to 30% more power with bifacial modules
To reduce LCOE and improve ROI on commercial and utility projects, bifacial is a great choice
Bifacial (literally meaning ‘two faces’) solar modules can generate energy not only from the front side but from the rear side as well – reflecting the sunlight on the ground to the glass-covered back of the module to produce extra energy in a solar-powered system. Ultimately, reducing the solar system’s levelised cost of electricity (LCOE) significantly and producing a higher return on investment (ROI).
Using its industry-leading bifacial cell technology and extensive knowledge of double-glass module manufacturing, Canadian Solar has developed a new generation of high-efficiency Poly Bifacial BiKu modules, which are supplied by SegenSolar. From the front side, the modules have a power output of 300W and 355W, while the rear side generates up to 30% of additional power. When combining both sides together, the total power output of a 355W Bifacial BiKu module can reach as high as 461W.
Depending on the reflectivity of the roof or ground conditions, daily energy yield for projects with bifacial modules can be 5-30% higher than with conventional polymer backsheet modules. This improved yield can dramatically enhance the economics of solar system deployments. Ideally, bifacial modules should be installed at least 1m from the surface of white membrane roofing.
The performance of bifacial modules also depends on various conditions such as system design, installation methods, location and so forth. There are four main factors which affect the bifacial gain of the module:
- Module height above the ground
It is recommended that the modules are fitted at least 20cm off the surface; but the larger the distance from the surface, the higher the bifacial gain will be. However, it’s worth noting this rule is only valid up to heights of approximately 1m. Above 1m in height, the bifacial gain increase is minimal.
- Module tilt angle
IAs with standard PV installations, the higher the tilt angle the better the bifacial gain. Although even modules with as little as 10° tilt can benefit from bifacial technology.
- Space between the rows (the pitch)
Bigger row spacing allows more light to reach the ground and rebound back to the rear side of the modules.
- Surrounding ground Albedo
Potentially a new term for most installers, ‘Albedo’ relates to the reflectivity of the surface. In general, the brighter the surface is, the more the surface reflects light – and, therefore, the higher the albedo will be. A higher albedo value means a bigger bifacial gain, so more additional power can be extracted from the module. For that reason, the highest bifacial gain can be achieved on white covering or snow-covered ground. Slightly lower but still considerable gains can also be achieved on light grey or beige roof covering. The lowest bifacial gain will be achieved on Asphalt or black covering but, because of the potential for considerable yield boost at a minimal price increase, bifacial modules should be considered for any flat roof systems.
How do bifacial modules work?
Bifacial PV panels offer greater power output when compared to conventional PV panels due to their ability to harvest light that is reflected onto the rear side. The reflected light can come from a variety of sources such as reflection from the ground or from a neighbouring row of PV modules.
Using a transparent backsheet (or glass) rather than a white backsheet on the rear side makes these types of modules will be more durable, due to the fact that both sides are UV resistant. In addition, using a glass backsheet and frameless design (certain modules only) dramatically reduces the PID (potential induced degradation) effect.