In 1881, the American inventor Charles Fritts created the first commercial solar panel. As the solar industry evolves, new technologies are caring the solar panels to the most advanced stage. The latest technology is so called PERC. It stands for Passivated Emitter and Rear Cell or Passivated Emitter and Rear Contact. It was developed in Australia in the 1980s by scientist Martin Green and his team at University of New South Wales. PERC technology adds an extra layer to the rear-side of a crystalline cell.

Today, let's delve at PERC technology and find out what it makes a difference in solar cells.

From top to rear, the lamination is:

– screen printed silver paste to form the contacts

– Anti Reflective Coating

– phosphorous diffused, boron doped silicon wafers that form the

P-N junction

– aluminum Back Surface Field (Al-BSF)

– screen printed aluminum paste

With this additional passivation layer is laid, it essentially enables the crystalline cells to improve light capture near the rear surface and to optimize electrons capture.

The key difference between PERC solar cells and standard solar cells is the passivation layer integrated to the back surface of the crystalline silicon cell. Three main advantages are boosted because of this additional layer of material.

This additional back surface passivation layer reduces “electron recombination” in the solar cell. To be simple, electron recombination is the tendency of electrons to recombine, which causes a blockage in the free movement of electrons through the solar cell. This inhibition of free electron movement leads to less-than-optimal cell efficiencies. In a PERC solar cell, electron recombination will be reduced in order to bump up efficiency.

A back surface passivation layer reflects light that passes through the silicon cell without being absorbed back into the silicon, giving the solar cell a second absorption attempt. This reflection of light means that more incoming solar radiation will end up being absorbed by the silicon cell, thus the cell becomes more efficient.

The third benefit from a PERC solar cell is the reflection of certain wavelengths of light. A silicon wafer in a solar cell can only absorb light in wavelengths up to 1180 nanometers (nm), and higher-wavelength light waves pass through the silicon and are absorbed by the solar panel’s metal back sheet, creating heat. When solar cells are heated, they operate at lower efficiencies. The back surface passivation layer in PERC solar cells is specially designed to reflect light with a wavelength above 1180 nm, reducing the heat energy in the solar cell and consequently increasing efficiency.

PERC technology kicks photons back into the silicon layers, causing the cell to produce more power and preventing electron recombination. These two benefits result in increased energy conversion efficiency and decreased heat in solar modules. They also ensure the cells work better in low light by producing meaningful voltage with less light than standard solar cells.

Finally, PERC solar cells are relatively easy to make because manufacturers can use almost all of the same equipment and materials they use to make less-efficient traditional solar cells. PERC technology can be added to both mono crystalline and poly crystalline solar cells, and works well in bifacial applications too.

So, a solar panel manufacturer such as Solarpro is able to achieve higher efficiencies than with standard solar cells which are reaching their physical limits. With the current state of the technology, it is possible to achieve up to 1% absolute gain in efficiency. While there are more steps in the manufacturing process, the gain in efficiency enables costs decrease, also at the system level in mass production at Solarpro factory.