Nowadays, more and more solar module manufacturers are bringing bifacial modules to market and the price gap is closing. But is it worth installing them on the roof of your home?
What is a bifacial solar panel?
With traditional solar panels, sunlight hitting the front of the panel is converted into electricity and the back of the panel has an opaque backing film. With a bifacial module, the light can also be collected from the back of the panel. These modules are made of glass/glass, which means they have a glass panel on the front and back.
Under optimal conditions, the performance increase can be significant. Hold on to this thought.
Bifacial panels on residential roofs
In most residential complexes, the conditions for a bifacial increase are anything but optimal. The panels are usually installed flush with the roof, about 10 – 15 centimeters above it. Under these circumstances, even a light roof doesn’t produce much reflection – and a dark roof even less. Bifacial solar panels can also be more difficult to install if they are frameless. although many are available with standard frames.
In these scenarios, installing bifacial panels will provide little additional performance (perhaps a few percent at best), but will not cause any damage. It can be advantageous if the panels are installed on a flat roof with a tilt frame, especially if the roof material has reflective properties.
The Solar Reflectance Index (SRI) is a percentage that measures a material’s ability to reflect solar energy and emit absorbed energy, where black is 0 and white is 100. Let’s just look at a few Colorbond (classic finish) colors commonly used in roofing materials, Surfmist has an SRI of 81 and Monument has an SRI of 27 – a big difference.
Photo credit: BlueScope Steel Limited
In fact, these modules are best suited for utility-scale solar farms, where they come into their own, as well as some commercial applications. However, they could be used around the home for some carport and pergola projects where the panels are essentially the roofing material.
Are there any advantages?
Bifacial solar panels can be more durable because the two layers of glass provide increased protection. But you can also get single-sided double glass panes – for example in the Trina Vertex S+ series; which are very affordable. Bifacial modules also generally have a lower temperature coefficient, meaning they tend to perform better in hot conditions than equivalent monofacial modules – but this also depends on the installation conditions.
So why even consider bifacial?
Not only are more and more solar module manufacturers producing them, some also only produce bifacial modules. Winaico (which makes good gear) comes to mind – the current lineup is all bifacial. So if there’s a brand that you particularly like and that’s all they make; It’s not really a problem.
Note that most bifacial solar panels are rated based on their front-facing capacity. For example, a 440W panel means 440W of power on the front. Back production should be a separate number and an estimate rather than fixed numbers. You may also come across the term “bifacial factor,” or coefficient, which indicates how well the back of a bifacial solar cell can generate power compared to the front. Typically it is in the 70-90% range; However, keep in mind that this is the potential and not the real performance on your roof.
Related: Learn everything you need to know about choosing solar panels for your home.
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