Which Is Better Bifacial Or Perc Solar Panels?

Solar panels have undergone rapid innovation in recent years, with two major new technologies – bifacial and passivated emitter rear cell (PERC) – promising increased efficiency and lower costs. But which of these new solar panel designs is better?

Bifacial solar panels were first developed in the 1980s, but have only become commercially viable in the last decade. They contain photovoltaic cells that can absorb light from both the front and back of the panel. This allows them to generate more electricity per panel.

PERC solar panels were also first created in the 1980s, but started widespread production in 2006. They contain an additional layer on the rear of the cell that reflects photons back to the front, increasing absorption and efficiency. PERC has become one of the most popular solar panel technologies.

How Bifacial Panels Work

Bifacial solar panels are able to generate electricity from both sides of the panel by utilizing light reflected from the ground and surroundings. Traditional solar panels only absorb light from the sun hitting the front side. Bifacial panels have solar cells encased in transparent material on both sides of the panel, allowing sunlight to hit the backside as well.

When sunlight hits the ground around the solar array, a portion of that light reflects back up onto the back of the bifacial panels. This allows the panels to absorb additional sunlight that normally would have been wasted in a traditional single-sided panel installation. By leveraging both direct and reflected light, bifacial solar panels can produce up to 25% more energy than monofacial panels.

How PERC Panels Work

PERC stands for passivated emitter rear cell. This technology increases the efficiency of solar panels by allowing the rear side of a solar cell to capture more sunlight.

In a traditional solar cell, the rear side is generally unpassivated and reflective. This means any sunlight that passes through the cell is simply reflected and wasted. With PERC technology, the rear side of the cell is passivated with a dielectric material. This reduces electron recombination at the rear surface, allowing the rear side to generate additional current.

PERC solar cells also have a patterned rear contact grid that further increases the active rear cell area. By enabling the rear side to capture more sunlight that would otherwise be wasted, PERC boosts the overall efficiency of a solar panel.

Efficiency

When it comes to efficiency, bifacial solar panels tend to outperform PERC panels. Bifacial panels are capable of producing 5-30% more energy over the course of a day than PERC panels of the same size. This efficiency advantage comes from the fact that bifacial panels can generate electricity from both sides of the panel – the front side facing the sun directly, and the rear side facing the ground. The ground reflects additional sunlight onto the rear of bifacial panels, resulting in extra energy production.

Bifacial panels have higher efficiency ratings from manufacturers, often around 19-21% compared to 18-20% for PERC panels. In real-world conditions, the bifacial gain can be lower or higher than the manufacturer ratings depending on factors like albedo (ground reflectivity). But overall, bifacial technology delivers superior efficiency and energy yields per square foot of solar panel.

Cost

When it comes to upfront costs, bifacial panels are generally more expensive than PERC panels. Bifacial solar panels cost approximately 10-15% more than comparable PERC panels with the same power output.

This is because producing bifacial panels requires some additional materials and manufacturing steps compared to PERC panels. The transparent backing that allows sunlight to reach the rear of bifacial panels adds cost over the opaque backing of PERC panels. There are also extra steps required during cell production and panel assembly for bifacial modules.

However, over the lifespan of the solar system, bifacial panels can potentially generate 10-20% more energy for only a slightly higher upfront cost. This can make them more cost-effective in terms of dollars per kWh produced over the long run.

When making a decision between bifacial and PERC, it’s important to consider total lifetime system costs and energy production, not just upfront panel costs. With their higher output, bifacial panels may justify their slightly higher initial price over the system lifetime of 25+ years.

Performance in Low Light

When it comes to low light conditions, bifacial solar panels tend to outperform PERC panels. Bifacial panels are able to generate electricity from both sides, capturing reflected light from the ground. This gives them an advantage over PERC panels which can only capture light from one side.

Various studies have shown that in low light conditions, such as early morning, evening, or cloudy days, bifacial panels can produce 10-30% more energy compared to monofacial panels like PERC. This performance advantage is most pronounced during the winter when the sun is lower in the sky.

So for locations that experience a lot of cloudy weather or have short winter days, bifacial panels are the better choice to maximize energy production year-round. The dual-side capture allows bifacial panels to take advantage of diffuse light conditions better than PERC panels can.

Performance in High Temperatures

When it comes to performance in high temperatures, bifacial solar panels typically outperform PERC panels. This is because bifacial panels can generate electricity from both sides, which allows them to run cooler. With PERC panels, the rear side of the panel heats up and reduces the efficiency of electricity generation. But with bifacial panels, the rear side also generates electricity, which draws heat away from the panel and keeps it running cool. This gives bifacial panels a clear advantage in hot climates where temperatures regularly exceed 25°C or 77°F.

Research has shown that bifacial panels can lose around 0.25% of rated power for every 1°C over 25°C. In comparison, monofacial PERC panels can lose 0.35-0.4% for every 1°C over 25°C. So in desert climates where temperatures frequently exceed 40°C, bifacial panels will typically maintain 5-10% better performance. Their dual-side electricity generation enables better cooling even in sweltering heat. For solar farms and systems in hot regions, bifacial is usually the superior option over PERC when it comes to high temperature operation.

Aesthetics

When it comes to aesthetics, bifacial panels tend to have the edge over PERC panels. Bifacial panels have a glass backing on both the front and back of the panel. This gives bifacial panels a very sleek, uniform look from all angles since both sides are covered in glass with solar cells sandwiched in between.

In contrast, the backside of a PERC panel is often just the plain white plastic backsheet material. Some people find this less visually appealing when compared to the smooth glass on both sides of bifacial panels. For some homeowners, bifacial panels are preferred for their symmetrical appearance on rooftops.

Additionally, bifacial panels come in either full black or transparent backsheet options. The transparent backsheet shows off the look of the solar cells on the underside, providing a high-tech aesthetic. PERC panels are limited to just the front side cell appearance.

When optimizing purely for visual appeal, bifacial panels tend to be the more attractive choice due to their sleek glass on both sides and greater customization options.

Lifespan

When it comes to lifespan, bifacial solar panels may have a slight advantage over PERC panels. Bifacial panels can potentially last 1-2 years longer in the field than mono PERC panels. This is because the dual-sided design allows bifacial panels to operate at lower temperatures, reducing thermal stress on the components. The slightly lower operating temperature can extend the lifespan of the encapsulant, backsheet, and solder joints. However, real-world longevity will depend on many factors like manufacturing quality, climate conditions, and proper maintenance. With high-quality manufacturing, both PERC and bifacial panels should provide 20-25 years of reliable performance. But bifacial’s cooler operating temperature gives it a slight edge for maximizing lifespan.

Conclusion

When deciding between bifacial and PERC solar panels, there are a few key differences to consider:

Bifacial panels can generate more energy as they absorb light on both sides, making them a better choice for locations that receive reflected light. However, they are more expensive than PERC panels.

PERC panels are a proven technology that can achieve high efficiencies at a lower cost, but don’t benefit from reflected light. They tend to have lower temperature coefficients, making them suitable for hot climates.

For residential rooftop systems, PERC panels may be the better choice as they provide good performance for less cost. For large utility-scale projects in locations with high reflectivity, bifacial panels can maximize energy generation.

In the end, consider the specific conditions of your installation and your budget. Bifacial panels will produce more energy in the right setting, but you’ll pay a premium. PERC panels offer reliable high efficiency at lower cost.