How do bifacial solar panels generate electricity?

Bifacial solar panels generate electricity using photovoltaic cells on both sides of the panel. The front captures direct sunlight, while the rear absorbs reflected or diffuse light from surfaces like rooftops, snow, or light-coloured ground. This dual-sided design increases energy output compared to traditional single-sided panels.

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Key components and process

• Dual-sided cells: Both surfaces contain light-sensitive silicon layers to convert sunlight into electrical charges.
• Transparent backing: The rear panel uses glass or translucent material instead of an opaque layer, allowing light to pass through and reflect back.
• Reflective surfaces: Ground-mounted panels or those installed over light-coloured roofs benefit most, as materials like gravel, sand, or snow bounce light onto the rear.

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UK-specific considerations

Advantages

• Higher efficiency in variable weather: Performs better on cloudy days and during winter, as the rear captures diffuse light common in UK climates.
• Snow resilience: Rear cells help melt snow faster by generating heat from reflected light, reducing downtime in colder regions like Scotland.
• Space efficiency: Produces 8–30% more energy per square metre than traditional panels, ideal for small businesses with limited roof space.

Limitations

• Installation complexity: Requires elevated mounting (e.g., ground racks or tilted rooftops) to maximise rear light exposure.
• Higher upfront cost: Typically 10–20% more expensive than monofacial panels, though lifetime energy gains may offset this.
• Surface dependency: Darker rooftops or heavily shaded areas reduce rear-side efficiency.

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Practical advice for homeowners and businesses

1. Opt for light surfaces: Install panels over light-coloured roofs, gravel, or grass to boost rear-side output.
2. Consider tilt angles: A 30–45° tilt improves light reflection in the UK’s latitude.
3. Check local permits: Ground-mounted systems may require planning permission, especially in conservation areas.

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Recent UK developments

• Commercial adoption: Large-scale solar farms like the Cleve Hill project in Kent increasingly use bifacial designs.
• Inverter compatibility: Most modern inverters work with bifacial systems, but confirm with installers to avoid mismatches.
• Government incentives: While the Smart Export Guarantee (SEG) applies to all solar, bifacial panels may qualify for additional business energy grants due to higher efficiency.

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Common mistakes to avoid

• Overestimating output: Gains depend on installation and environment, not a flat 30% increase in all conditions.
• Poor maintenance: Keep the rear side clean, as dirt buildup reduces reflected light absorption.
• Ignoring warranties: Verify if warranties cover rear-side performance, as not all manufacturers include this.