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What are bifacial solar panels, and why are they awesome?

Avatar for Hatham Al-Shabibi
Published on 07/09/2019 in
Updated 11/08/2019
bifacial solar panels viewed from underneath

In short: In short: Bifacial solar panels are a smart, efficient way to harness even more of the sun’s energy; typically 11-20% more energy is captured than energy from traditional PV panels. Bifacial solar panels are in the spotlight these days because they recently became exempt from President Trump’s Section 201 solar panel tariffs. Bifacial solar panels are a young niche in the solar market poised for mass-scale adoption.

Bifacial might sound like something you’d get done at the salon, but we’re not talking about avocado paste. Bifacial solar panels are a newer entry into the solar panel market, and while they won’t improve your complexion, they can power your stylist’s ceramic hair dryer.

What are bifacial solar panels?

When you think of solar panels, you imagine slabs of metal and giant panels made of monocrystalline or polycrystalline silicon attached to roofs, typically angled with the roof and south-facing. Their purpose is to absorb the sun’s energy from one side – the side facing up towards that giant fireball of life.

But what about all that sunlight that hits the ground and reflects back up? When we look down at the ground, we don’t see the ground itself emitting light – we see the ground reflecting the sun’s light back up to our eyes. Obvious when explained, but not something we often think about.

Bifacial solar panels take advantage of that overlooked illusion – and the energy contained within it. They are essentially double-sided solar panels: the top side does what normal solar panels do and capture the sun’s light directly; the bottom side captures the light reflecting back up from the ground – resulting in more energy absorbed and higher efficiency! Both sides are covered with glass, which helps encapsulate the silicon on the front and rear of the panels.

How are bifacial solar panels different from regular solar panels?

Aside from the 2-for-1 special described above, bifacial solar panel systems are ideal for utility-scale, commercial installations. They usually cost more than a traditional solar system, and the extra space inherent in a large-scale system is preferred (so more light reflects from the ground).

They’re typically thinner in profile than traditional panels due to framing, and the need to have as few materials as possible (like racks, support, etc.) covering the rear. Their junction boxes (housings that protect the panel’s electrical components – and help prevent power from returning to the panel with the use of diodes) are modified into smaller units to prevent shading on the back of the panel.

Some bifacial panels have a studded aluminum rear contact, which creates channels for light to pass through the front of the panel then straight through to the rear (instead of just reflecting that light away in the front).

What makes bifacial panels better than traditional solar panels?

The clearest advantage is the extra power generated by added sunlight reflected from the ground, while keeping more or less the same footprint and aesthetic of a traditional solar system. The added energy claims run a wide spectrum, from 8% increased solar energy all the way to 30% extra power.

Bifacial solar panels are considered more efficient than traditional panels, mostly because they produce more energy with about the same number of parts, and have the same footprint as a traditional panel.

Are there downsides to bifacial solar panels?

They might not be best for residential use, mostly because the panels need to be angled away from the mounting surface so the light underneath isn’t “squashed” by the small space between the panel and roof. They also perform better partnered with solar axis trackers, which are programmed to turn the panels as the sun moves across the sky.

Bifacials don’t have much penetration in the US solar market (yet), so there aren’t as many companies installing them and providing warranties/support. This is about to change though…see below. (ANCHOR)

Bifacial solar panels fare much better being ground-mounted rather than on your roof; that way, they can be angled away from the ground so more light can reach the back of the panels.

Pergolas are also a good option. Everyone loves those! What better way to cap off your garden or yard entrance than with a gorgeous structure – vines trailing up and all – outfitted with solar panels? Your pergola can help you save money!

Scrabble pieces spelling the word tariff

Our unofficial pick for Word of the Year.

I’ve seen the term ‘bifacial solar panels’ in the news lately. What’s happening?

The entire solar panel industry has been in the news a lot lately, thanks to our unofficial pick for Word of the Year: tariff.

This begins all the way back in January 2018. Winter fell upon the solar panel industry when President Trump levied a 30% tariff (basically, an extra fee) on all solar panel imports, officially called Section 201. This significantly affected the Chinese panel industry; in fact, 201 was designed to do just that. You can check out this fact sheet to read the fed’s rationale for the tariffs yourself. The tariff raised solar prices for consumers an average of 5.6 percent, which has steadily declined around 0.5% each month.

Section 201’s 30% tariff decreased to 25% in 2019. In 2020, it’ll drop to 20% and so forth until it reaches zero (unless it’s renewed – we don’t want that).

Fast forward to June 2019, and the Trump Administration announced that bifacial solar panels are exempt from the Section 201 tariffs. Naturally, this made pretty big headlines in the energy industry, despite the low 1% penetration bifacial panels currently enjoy.

How and why did this happen? Against all odds, the Solar Energy Industries Association (SEIA) successfully convinced the administration to consider the exemption in order to increase production and adoption in the US. By excluding bifacial panels from Section 201, developers arguably save money by switching to them from traditional panels, which are more expensive with the tariff applied.

To put the Chinest imports into perspective, that country exported 2,868MW of solar panels to the US in 2016. In 2018, only 46MW were imported. That’s a massive drop in power, and that drop was also influenced by new anti-dumping (AD) and anti-subsidy (AS) laws in China.

Despite the bad news on imports, the US saw only a 2% decline in installations last year, suggesting that the industry is now so healthy and robust that tariffs and bad policies can no longer kill it. The projections for residential installations go in the right direction (up) through at least 2024.

bifacial solar panel on top of a building at dusk

A large bifacial solar panel installation. Notice how the panels are angled and raised away from the roof surface, allowing light to bounce up from underneath. Photo: Biel Morro

Bifacial Future

Just as traditional solar systems continue to decrease in price, the cost of bifacial solar panel systems will also drop the more popular they become. In fact, due to the increased efficiency a bifacial panel provides, their price isn’t that much different versus a traditional panel: an average increase of just $0.02 to $0.03 per watt.

Developers will also figure out ways to make them more appropriate for residential use, such as thinner panel cells and smaller frames/racks so more light can pass through in a home setting. More manufacturers are already entering the residential market, such as Longi and Prism.

The National Renewable Energy Laboratory (NREL), considered a leader in solar energy resources and innovation and the overall governing solar body in the US, is working hard to develop the first standard module rating system for bifacial solar panels.

How awesome is it that humans have reached the point where we capture energy from light hitting the ground and reflecting back? That’s mind-boggling. Despite the usual cynical news cycle, groundbreaking innovations are happening around the world from smart people who care deeply about reducing our impact on the planet.

We exist today in the midst of a historical, world-changing shift away from polluting, earth-depleting resources like gas and coal to a renewable world with solar and wind – a shift our ancestors will read about in textbooks (well, by then textbooks will be holograms). Bifacial solar panels are a microcosm of a greater human urgency and ingenuity, and you can be a part of it!

Last modified: November 8, 2019

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