Innovative concepts like bifacial solar panels allow for increased energy production and efficiency while taking up less space.
According to a high-quality IEA Photovoltaic Power Systems Programme (IEA PVPS) report, bifacial solar panels will account for around 30% of the world market share by 2030. If you’re considering installing solar panels, you should aim for a system that allows you to generate as much solar power as possible.
Bifacial solar panels offer better energy yields in small-scale and large-scale installations than traditional monofacial solar panels. But what are bifacial solar panels, and how do they work?
Quick Takeaways:
- Bifacial solar panels generate power from both sides
- They can offer 10% to 30% more energy than traditional panels
- Most bifacial panels are made using monocrystalline
- installation requires careful planning and consideration for reflectivity and mounting
What are Bifacial Solar Panels?
Bifacial solar panels have solar cells on both sides, allowing them to absorb sunlight from the front and the back. Traditional solar panels only capture sunlight on one side, hence the name monofacial.
Bifacial panels can capture reflected light, often called albedo light, which bounces off surfaces beneath the panel and the surrounding environment. The dual-sided energy collection makes bifacial panels more efficient than traditional panels, resulting in a higher energy output from each panel.
Traditional panels usually have opaque back sheets that block and reflect light away. With bifacial panels, the back sheet features a transparent or glass design that allows sunlight to pass through to the rear side, where solar cells capture the residual ambient light that bounces back.
How Do Bifacial Solar Panels Work?
Bifacial solar panels operate on the same photovoltaic principles as standard panels. Light hits the solar cells, activating electrons within the cell’s material. The activated electrons move through the cell, creating an electric direct current (DC) extracted through conductive material and converted to alternating current (AC) for use in your home.
The difference lies in the ability of bifacial panels to generate energy on both sides:
- Front Side: The front captures direct sunlight, just like conventional panels.
- Rear Side: The rear collects light that has reflected off surfaces below the panel.
The efficiency of the rear side depends heavily on the reflectivity of the surface beneath. Reflective materials like white sand, snow, or light-colored concrete significantly enhance energy collection. In contrast, dark or matte surfaces like soil or asphalt offer less reflectivity.
How Much More Energy Can Bifacial Solar Panels Generate?
Increased energy yield is one of the most significant selling points of bifacial solar panels. Studies show that bifacial panels can produce between 10% and 30% more energy than traditional panels.
Optimally tilted, standalone, bifacial panels can outperform traditional panels by at least 10% anywhere in the world. When you incorporate an elevated panel fixture, the back side sees a more significant portion of the ground and collects more reflected sunlight, increasing the energy gain to 30%.
The different positioning strategies allow the bifacial panels to capture more ambient and reflected light, particularly in environments with high albedo. The panels perform best when installed near highly reflective surfaces like water bodies, glass, stone, or sandy and snowy areas.
What Are Bifacial Panels Made Of?
Most bifacial solar panels are made from monocrystalline cells, which offer a higher efficiency to maximise energy output. Some manufacturers also use polycrystalline as a cost-effective alternative. Both sides of the panel use PV cells designed to absorb light effectively, with the rear side optimized to capture reflected or ambient light.
Other materials used include:
- Encapsulation layers – Encapsulation layers protect the solar cells and enhance their durability by shielding them from moisture, dirt, and mechanical damage. Manufacturers use ethylene vinyl acetate (EVA), a transparent, flexible material that bonds the cells to the surrounding structure.
- Front and Rear Covering – Instead of an opaque back sheet, bifacial panels use transparent materials like tempered dual glass for the front and rear. The dual-glass design is robust, providing structural strength, improving transparency, and enhancing the panel’s resistance to moisture, UV radiation, hail, and strong winds.
- Metal Frame – The frame provides structural support and is typically made of anodized aluminium, which is lightweight, corrosion-resistant, and durable. Some bifacial panels, especially those with a dual-glass design, are frameless to reduce shading and improve aesthetics.
- Anti-Reflective Coating – Manufacturers also apply an anti-reflective coating to the glass surfaces to increase light transmission and reduce glare. This coating ensures more sunlight reaches the cells, enhancing the panel’s efficiency.
- Busbars – Busbars are thin metal strips, usually made of silver or silver-coated copper, that conduct electricity within the panel. They connect the solar cells and transport the generated current to the electrical system. Multi-ribbon and multi-wire busbars enhance cell performance by lowering cell spacing and improving connections.
How Are Bifacial Panels Installed?
Installing bifacial solar panels requires careful planning and specific considerations to maximize their performance and ensure durability.
Site Assessment
A thorough site assessment helps determine the optimal conditions for maximizing energy output:
- Reflectivity (Albedo): The surface beneath the panels should have a high albedo for better rear-side performance. White gravel, concrete, or reflective coatings can offer good reflectivity.
- Shading Analysis: To ensure both sides of the panels receive sufficient light, avoid trees, buildings, or other obstructions.
- Ground Characteristics: The site should be stable and suitable for the mounting structure to prevent settling or shifting over time.
Mounting Structure Design
The mounting structure is crucial for bifacial panels, as their performance depends on elevation and exposure.
- Height: Bifacial panels are typically installed at a greater height than traditional panels (at least 1 meter off the ground) to allow more light to reach the rear side. This spacing also enhances airflow, reducing panel temperatures for improved efficiency.
- Tilt Angle: The tilt angle must be optimized to ensure maximum sunlight exposure to both the front and rear surfaces. It’s usually calculated based on the latitude, seasonal sun angles, and the reflective properties of the ground.
- Tracker Systems: Solar trackers, which move the panels to follow the sun’s path, are often paired with bifacial panels. The setup boosts energy output by optimizing sunlight capture throughout the day.
Framed bifacial panels are usually easier to install than frameless designs because traditional mounting systems are adapted to framed models. However, most manufacturers offer clamps to mount frameless panels. These typically feature rubber guards to protect the glass, and installers must ensure they don’t tighten the bolts excessively and damage the glass.
Orientation is also crucial since it ensures the panels face the optimal direction. Studies show that bifacial panels perform best at high altitudes when optimally elevated and facing the equator or mounted on a tracking system.
Vertical designs are more attractive and cost-effective at low altitudes due to advantages like a wider area for energy generation and low accumulation of debris or soil. They also leave more land available for other uses like farming or livestock.
What Are the Benefits of Bifacial Panels?
More Energy
By getting light on both sides, bifacial panels produce more energy than single-sided panels. They can offer 10% to 30% more energy than traditional panels, translating to quicker and more return on investment.
Durability and Longevity
Many bifacial panels are made with tempered glass on both sides, making them more durable. This robust construction protects against weathering and wear and tear and can extend its life beyond the 25-year industry standard.
Aesthetics
The modern design of bifacial panels makes them an excellent choice for architectural applications. Their transparent or dual glass design blends with any environment, whether used in canopies or building integrated photovoltaics (BIPV).
Flexibility
Bifacial panels are flexible and can work in any environment. Their dual-sided design captures energy in any condition, from residential rooftops to large-scale solar farms and even floating solar. They require less space than traditional panels and can even be installed vertically.
Environmental Benefits
More efficiency means fewer panels to generate the same amount of energy. This translates to less material mining or manufacturing processes that use fossil fuels. It also reduces the amount of waste from obsolete solar panels.
What are the Drawbacks of Bifacial Panels?
Higher Upfront Costs
Bifacial panels cost more upfront than traditional panels. However, the extra energy payback can be worth it over time, especially for larger installations.
Installation Complexity
Bifacial panels require more planning. Panel height, tilt, and ground surface need to be optimized so the back side gets enough reflected light. They may not be suitable for most residential rooftops, especially those with pitched roofs. Optimal performance is usually achieved on ground-mounted systems or flat roofs.
Weight
Dual glass construction is durable but adds up to 2kg to each bifacial panel’s weight. This can be a challenge for transportation and installation, especially for rooftop systems.
Variability in Efficiency Gains
The benefits of bifacial panels depend heavily on environmental conditions. Their performance may not exceed traditional panels in areas with low reflectivity or inconsistent sunlight.
Which are the Best Bifacial Solar Panels in the UK?
1. REA Fusion Energy Solar Panels
Efficiency: 22-24%
Cost per panel: £400 to £420
The REA Fusion solar panels are bifacial and can guarantee more power than single-sided panels. They’re double-glazed for maximum durability and made from high-efficiency N-type M10 Topcon solar cells.
The REA Fusion panels have a seamless, sleek design, and you can choose between black and silver. They’re also microinverter optimised, enabling them to work with enphase micro-inverters that allow electricity generation even in low-light conditions. This makes them ideal for the UK’s cloudy weather.
Thanks to the double-glazed design, you don’t have to worry about delamination, where the panel components detach from each other. You can also monitor the performance of each panel through a user-friendly application on your phone or computer, making it easier to determine how the weather will impact performance.
2. REC Alpha Pure-R
Efficiency: 22.3%
Cost per panel: £94 to £117
The REC Alpha Pure-R Series builds on the successes of previous REC Alpha products in uniting leading cell technology to create a revolutionary, robust, and reliable solar panel that hits the sweet spot in terms of power, weight, and size.
These bifacial solar panels come with a 25-year product warranty and a performance warranty that guarantees at least 92% of its original output after 25 years, which is superior to many other panels in the market.
The bifacial design enhances energy yield, and the panel’s design incorporates advanced cell technology and robust materials to withstand harsh environments. REC strongly focuses on sustainability and uses low-carbon manufacturing processes.
3. Yingli Solar Panda Bifacial 144 Cell
Efficiency: 22.5%
Cost: N/A
The Yingli Solar Panda Bifacial 144-cell solar panel is a strong contender if you want to balance efficiency and cost. It uses advanced N-type bifacial cell technology to generate electricity from both sides of the panel, increasing energy yield by up to 30% in optimal conditions.
The panel boasts a power output of around 415 watts and an efficiency of 22.5%, placing it among the more capable models in its category. Notable strengths include its durability and heat tolerance. While its temperature coefficient is slightly less favourable than some competitors, its overall build quality ensures reliable performance in diverse climates.
The panel comes with a 12-year product warranty and a 30-year performance warranty, which guarantees 82.5% of its initial output at the end of the period.
However, the shorter product warranty and modest heat resistance might be concerning compared to premium brands, especially if you live in a region with extreme temperatures.
4. LONGi Solar Hi-MO 5
Efficiency: 21.3%
Cost: £104.77
The LONGi Hi-MO 5 solar panels are designed with advanced N-type TOPCon technology and dual-glass construction, offering high efficiency and durability. It delivers power outputs ranging from 540 to 600 watts, with an efficiency rating above 21%.
Key features include its excellent performance in low-light conditions and superior temperature coefficient (-0.35% per °C), making it ideal for residential and utility-scale projects in various climates. LONGi claims that the Hi-MO 5’s bifacial nature can improve overall system output by 10-30%, depending on the albedo and installation conditions.
The Hi-MO 5 comes with a 12-year product warranty and a 30-year performance warranty, ensuring a minimum of 84% power output at the end of its lifespan. Its robust dual-glass design enhances resistance to environmental factors like humidity and temperature fluctuations, further extending its durability.
Final Thoughts
Bifacial solar panels allow you to harness solar energy from both sides and increase output. Combined with their durability and aesthetic appeal, they’re well-positioned to change the renewable energy landscape. While they come with some challenges, their benefits make them a compelling option if you’re looking to embrace solar power.
Sources and References
- https://iea-pvps.org/wp-content/uploads/2021/04/IEA-PVPS-T13-14_2021-Bifacial-Photovoltaic-Modules-and-Systems-report.pdf