PERC Solar Cells

One of the hurdles to very widespread use of solar energy is having enough space for photovoltaic solar panels. Some homes don’t have enough sunny roof area to generate all their own electricity. Utility-scale solar farms need a lot of land to generate enough solar electricity for thousands of homes and businesses, but most cities don’t have much vacant space.

Boosting solar panel efficiency would help advance the solar energy industry, but researchers are having trouble dramatically increasing solar panel efficiency. One effective technology is Passivated Emitter and Rear Contact (PERC) solar cells, which are sometimes referred to as Passivated Emitter and Rear Cell.

Thanks to researchers, PERC solar technology has been steadily advancing in recent years and is now widely used by most solar panel manufacturers. Today, PERC solar panels are reaching efficiencies 12% higher than panels with standard solar cells, plus they work better in low-light and high-temperature applications.

What Are PERC Solar Cells?

PERC cells offer improved solar efficiency so they can generate more electricity from the same amount of space. This can also reduce solar system costs because if high-efficiency solar panels can generate the same amount of solar energy, then this system will have lower labor, wiring and racking costs.

First introduced in 1989, PERC cells are modified versions of the conventional monocrystalline solar cells that are widely used in the solar energy industry today. The cost of PERC solar modules is slightly more than conventional crystalline modules because additional steps are needed in the production process. However, manufacturers are able to use the same equipment and do not need to retool factories to produce these panels, which is why production costs are only modestly greater, and manufacturers have so readily adopted PERC cells.

The increased costs are easily justified by greater energy production, and PERC solar cells have pretty much become the industry standard.

How Do PERC Solar Panels Work?

The conventional solar cell structure contains two layers of silicon, called “p-type” and “n-type” for their positive and negative charges. The solar module produces an electric current when the sunlight hits the solar cells and knocks electrons loose from the n-type layer, and the p-type layer takes them.

PERC solar panels have modified silicon solar cells. The difference between PERC solar cells and conventional crystalline solar cells is a reflective passivation layer on the back surface field that reflects unused light back across the solar cell like a mirror. This gives the light a second chance to be absorbed by the solar cell, boosting electricity production, even in low-light applications.

When solar panels become too hot, their efficiency decreases. The passivation layer on PERC technology also reflects longer wavelengths of light that the silicon wafers cannot absorb. This boosts performance because it reduces heat absorption.

Also, electrons tend to recombine in conventional solar cells, which blocks the free flow of electrons, reducing electricity generation. Another benefit of PERC solar technology is that electron recombination is reduced, which boosts conversion efficiency.

Although researchers encountered some issues of increased light-induced degradation of PERC solar cells, they have since made significant progress in efficiency. This technology is likely to continue to improve with further research.

Types Of PERC Solar Cells

Solar cells and other electronics have semiconductors, which have specific electrical properties. Both monocrystalline and polycrystalline solar cells have silicon as a semiconductor, but they each use a different type. Because of this, mono-PERC and poly-PERC cells have different performance characteristics and visual appearances.

Mono-PERC Cells

Monocrystalline solar panels are made with pure silicon and have a black appearance (not a blue hue). As the name indicates, they have a single silicon crystal, and they have some advantages over polycrystalline solar cells. Mono-PERC cells are typically more efficient in converting sunlight into solar electricity and perform better in hot weather. However, they also usually cost a bit more due to a complex manufacturing process. 

Poly-PERC Cells

The first solar modules developed used polycrystalline silicon solar cells, and the manufacturing process entails melting fragments of silicon to form a wafer. Unlike monocrystalline cells, which have a black appearance, these solar cells have a blue hue which can make these panels stand out more on a roof.

They are usually several percentage points less efficient than monocrystalline solar panels, but utilizing PERC technology can help increase their ability to convert sunlight into electricity, especially in hot weather.

How Efficient Are PERC Solar Panels?

The maximum efficiency of mono-PERC cells is about 23%, compared to 21% for conventional monocrystalline solar cells.

PERC technology can also be applied to polycrystalline solar panels, but they will be less efficient than mono-PERC in generating solar energy. Although thin-film solar is usually less efficient than both mono and poly panels, it is also commonly less expensive, so it is appealing for projects with limited budgets.

Who Makes PERC Solar Cells?

Today, PERC panels are widely used in new solar installations, and they have an estimated 75% market share, according to the International Energy Agency. These solar panels are widely available to solar installers because most manufacturers use PERC technology in at least some of their modules. For example, Canadian Solar, JA Solar, Jinko Solar, Hanwha QCELLS, Panasonic, REC Solar, Silfab, SunPower, Suntech, Trina and Vikram Solar all use this technology in their products.