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The Sun. What a majestic star that we on Earth revolve around. Its power gives us light, gives us warmth – it gives us life. And its energy is one of the few resources that no human being may own or control. We, as citizens of the Earth, have a responsibility to promote solar energy use, and we should do so immediately! In heeding this call, we find ourselves researching, experimenting, and striving towards optimum power outputs, to sustain our power needs. The ultimate objective is finding the means to maximum, optimum yields. An emerging, effective trend is in the use of bifacial solar panels, over traditional mono facial panels.

The more the merrier! Bifacial solar panels? A dynamic duo, more like “greater-yield” solar panels!

The prefix “bi” denotes something having “two”. Hence, bifacial solar panels are simply two-faced/two-sided. In the more technical sense of the word, bifacial solar panels have components (solar cells) on both sides of the panel, to harness solar power. Whilst, traditionally, panels have opaque backs, hence, mono facial.

Understanding basic solar harvesting concepts

It is important to note that double-faced does not necessarily imply double yield. That’s impossible. We must understand concepts of solar motion and shading. The motion of the sun changes the angle at which light strikes the earth and consequently, the solar panel’s face. The principle of solar energy harvesting from solar cells are as such:

  • Picture the angled surface of a traditional photovoltaic (PV) panel.
  • As the sun’s rays strike the absorbing surface in a perpendicular fashion – the power density and solar intensity is at its peak.
  • Now, as the sun “moves”, the angle at which the rays hit the surface, changes – reducing the solar intensity on the panel.

Reflectivity plays a big role in solar cell absorption. Lighter colors (white, silver, etc.) on surfaces below panels reflect way more than darker colors and grassy surfaces.

The end goal – greater solar yields!

Now, what happens when another surface is utilized in the panel? For example, in the case where bifacial solar panels are fixated onto well reflective facades – an increase of 15 – 30% in solar power yields has been reported. And this is due to the additional energy harnessed from the rear side of the panel.

This shows a major solar design factor in this technology: the type of substrate (i.e., layer or material) found behind the panel. This directly influences the solar reflectivity that the rear side of the panel needs for energy harvesting. As a result, when the vehicle is lighter and more reflective, the amount of solar power harvested from the vehicle’s rear side increases by 20%, increasing overall efficiency.

Bifacial solar panels – solutions to a brighter future!

The solar industry thrives on the development of high-efficiency technology. The use of bidirectional solar panels is therefore highly desirable. The priority on utilizing quality materials for increased energy yields is great. It already possesses the advantages and operation of a single-faced panel. Now it serves as an upgrade, allowing for increased yields through improved low light performance coupled with a lower temperature coefficient.

Mounting and installation – a critical factor

Bifacial solar panels either utilize dual-glass or clear back sheets. In using transparent rear sheets – their solar cells facilitate rear-side energy harvesting. Tilt angle is very critical when installing bifacial solar panels. The greater the tilt of the panel, the greater the yield generated. Light reflection will be limited and will not penetrate the rear-side cells if installed parallel to a rooftop’s natural sloped surface. As a result, ideal mounting conditions include tilting on flat rooftops and ground-mounted systems. This allows for greater tilt potential and plenty of space for the reflected light to hit the backside of the panels. Panel junction boxes have also been reduced in size or relocated to avoid shading.

Why choose bifacially?

  1. With an additional surface in this titled system – there is a greater surface area for solar energy harvesting. Solar reflection is a phenomenon that occurs in any system – why not capture it and use it for our benefit!
  • You get to sing “I’ve got sunshine on a cloudy day”. That’s not entirely a joke. Due to solar reflection, the rear-side cells may still be able to harness power and thus be productive. Bifacial panels are more durable when left to the elements and have longer warranties than traditional panels.
  • It is possible to produce two energy peaks during the day with optimal mounting and installation. In order to harvest morning rays, half of the panels in an array system are tilted towards easterly directions. This is an example of innovative thinking. The other half – tilted west for afternoon, sunset rays. Even when installed vertically, panels can produce energy!

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