Monofacial or bifacial solar panels - which one is right for you?

We recently added a new type of solar panel to our Robinsun Performance range, from top brand Aiko. This monofacial solar panel complements our bifacial solar panel from QN Solar. So which solar panel should you choose for your plug & play solar kit?

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What is the difference between monofacial and bifacial solar panels?

As the name indicates, the difference between monofacial and bifacial panels is the amount of sides the solar cells are exposed to the sunshine. In monofacial panels this is on one side only, for bifacial panels it is on both sides. In monofacial panels, the cells are fixed on a lightweight, non-transparent surface, making the panel relatively light (about 20 kg). For cells to be exposed on both sides in bifacial panels, a double layer of tempered glass is required, making panels a bit heavier (about 24 kg).

In the case of bifacial solar panels, there is a main side, that determines the declared maximum output power, that in the case of our current QN Solar panels is 420 Wp. If you were to use the same panel the other way around, it would produce about 85% of that. The advantage of bifacial solar panels is that they can produce electricity at the same time from both sides. This extra production is of a maximum of 30%, bringing the 420 Wp QN Solar panel to a theoretical maximum output of 546 Wp, significantly more than the Aiko&#;s 455 Wp.

Which panel type is best for what application?

If you reach this 30% extra production with a bifacial solar panel depends on how much irradiation the rear of the panel receives. To maximize it, the panel needs to be installed at ideally 1 m or more distance from a surface. This surface needs to reflect the sunlight very strongly. A white wall or a pool filled with water will reflect a lot, a lawn very little. Therefore, if you plan to install your kit on a pergola, a balcony with a transparent railing, or close to a pool, the bifacial panel is probably your better option.

If you plan to install the solar panel on a tile roof or on a lawn, you will probably not produce a lot with the rear of the panel, and the better choice is a more powerful monofacial panel for your plug & play solar kit.

Conclusions

To maximize the performance of your plug & play solar kit, choose the right panel for it. If you have a chance to get a lot of irradiation on the back, the bifacial panel is the better choice. If there is no irradiation on the back, you&#;re better off with a monofacial panel. Either way, installing a plug & play solar kit is the right thing to do, for our planet and for your wallet.

Looking into the economic and efficiency aspects of projects, more and more project owners requires bifacial modules to be installed instead of monofacials. But is this choice correct for all situations? Let's have a more detailed look on what are main differences between both types of modules and which projects requires which kind of panels.

Key differences between monofacial & bifacial PV modules

In monofacial photovoltaic modules sun's energy is absorbed from one photovoltaic side and bifacial modules capture solar light from both sides: front and back sides.

Figure 1 &#; Monofacial and bifacial modules' working principle scheme (Source: Internet)

As we can see from Fig.1 - standard monofacial module has 3 basic layers (plus EVE glue between layers): glass, solar cells and TPT back sheet. Panel is able to absorb only direct sunlight falling on its surface as back sheet is not transparent. While structural specifics of bifacial modules are: front cover glass, solar cells and rear cover glass, or may be also transparent back sheet in cheaper version

Nowadays, the majority of solar panels available in the market are still monofacial modules. But bifacials are a new solar product trend emerging recently in solar industry around the world.

In general, here are main advantages of monofacial and bifacial panels:

Monofacial

• Absorb the sun&#;s energy from one photovoltaic side and can work on all surfaces
• The majority of modules in the market, easier to find suitable power
• Less expensive
• Lighter than bifacial panels

Bifacial

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• Double-sided and absorb energy from both sides
• Higher energy output per square meter, up to 30%
• Can be set up at any angle
• Longer warranty up to 30 years

Solar installation design

Utility scale/C&I

The ideal conditions for bifacial solar panels is in utility scale PV installations or big commercial/industrial projects. Especially together with solar trackers for maximum power output. Such systems with trackers can increase final output up to 30%. When a bifacial solar panel is mounted on the ground or on special roof constructions, as it is done for most of big systems, sunlight that reflects from the ground or roof can be absorbed by back-facing solar cells. But surface should be reflective and clean, like sand, snow, reflective roof material, etc.

Figure 2 &#; Eco Green Energy solar panels Atlas 550W bifacial, Macedonia (Source: EGE)

So if your project has less requirements to budget, and more to efficiency, plus it's installation on reflective ground or roof - bifacial panels are the best choice. If you are looking for more "money save" solution and there are bad ground conditions or you have standard tile roof - probably better to take a look at monofacial PV.

Residential

Taking into consideration price range comparing with traditional monofacial panels, and requirements for installation conditions with reflected light. In most cases, bifacial solar panels are not the best choice for residential rooftop PV installations.

Figure 3 &#; Eco Green Energy solar panels Helios Plus 375W monofacial, Lithuania (Source: EGE)

Of course if your residential project has free-standing structures like pergolas, system can benefit from bifacial PV modules, which will be able to provide partial shade in addition to generating energy. Bifacial panels can also be used in any other case where there is nothing directly behind the solar panels to allow reflected light to reach the back of the modules. In all other cases - standard monofacial modules in silver, black frame or full black will be the best choice.

Conclusion: are bifacial solar panels worth it?

Bifacial PV modules may be worthwhile for commercial/industrial and utility solar projects, but they typically don&#;t make as much sense for residential rooftop installations. Additional costs for installation and surface management means that average homeowners would still probably be paying more to install bifacial panels comparing with monofacial. In addition, efficiency increase won't be that obvious for small residential households.

Also check our complete guide to bifacial solar panels and find more exiting facts about bifacial panels market.

Get in touch with Eco Green Energy's sales representative or contact us for more information.

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