In order to get higher efficiency and quality but reduce manufacture cost, Solar cell technology is always evolving and improving. PERC solar cells nowadays is popular with the solar PV industry. PERC stands for Passivated Emitter and Rear Cell.
Introduction to PERC technology
A PERC solar cell is simply a more efficient solar cell, meaning that solar panels built with PERC cells can convert sunlight into electricity more efficiently. Solar panels encapsulated with PERC solar cells typically perform better than conventional panels in both low irradiance conditions and high temperatures conditions. PERC technology boosts efficiency through the addition of SiO2 or Al2O3 thin film layer to the back of a traditional solar cell, which provides several benefits to the cell’s efficiency.
Additionally, upgraded to PERC manufacturing doesn’t require a lot of modifications to existing cell manufacturing processes. It’s a relatively easy shift for manufacturers to start producing higher efficiency PERC cells at a low cost.
The difference between PERC solar cells and standard solar cells
A PERC solar cell is not much different in construction from a typical photovoltaic solar cell. Both types of solar technology use silicon wafers to generate a flow of electrons using incoming solar radiation, and the overall construction of the cell types is very similar. The main difference between PERC cells and typical monocrystalline photovoltaic cells is the integration of a back surface passivation layer, which is a layer of material on the back of the cells that provides three main benefits that boost cell efficiency.
How does a back surface passivation layer lead to gains in solar cell efficiency? Here are the three ways the passivation layer in a PERC solar cell increases overall efficiency:
1. Reflection of light from the back of the cell
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.
2. Reduced back surface recombination
The addition of a back surface passivation layer reduces “electron recombination” in the solar cell. Simply put, 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 is reduced in order to bump up efficiency.
3. Reduced heat absorption
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.
Additional steps of PERC solar cell
PERC technology can be so powerful is obvious efficiency gain but the minimal investment it takes to begin manufacturing PERC solar cells instead of standard monocrystalline solar cells. In order to produce a PERC cell, there are two additional manufacturing steps needed:
Application of the back surface passivation layer
Laser/chemical etching to open small pockets in the passivation layer
These two steps don’t add significant costs to the solar cell manufacturing process and result in a higher quality, more energy-dense solar cell. A classic barrier to new solar cell technology is the cost of new equipment production, and PERC solar cells require very little monetary investment to upgrade to a better product.
Process flow of PERC and Bifacial PERC solar cell
PERC and BiPERC(Bifacial PERC) process flow shows in the following picture.
Benefits of PERC technology for Solar PV investment
Solar panels built with PERC technology indicate more energy density solar installations. This implies that you can generate the same amount of power energy using fewer PERC solar panels than they would with more conventional solar panels. Consequently, by needing fewer solar panels for your installation, your costs can be reduced. Additionally, the fewer panels you need, the more flexibility you have on your roof to position your panels. If suitable roof space is limited, using PERC solar panels or any high-efficiency panel product can make a solar installation capable of the power you need a reality.
Reducing the number of solar panels you need has the benefit of lower the balance-of-system (BOS) costs for your solar power system. BOS costs are generally any costs involved in solar installation components that are not the solar modules themselves. Inverters, racking and wiring all factor into your BOS costs, and the fewer panels you need, the fewer complementary components you’ll need as well.