PERC solar cells: What you need to know

Solar cell technology is constantly evolving and improving. PERC solar cells are a relatively new innovation in the solar industry - in this article, we'll dive into what PERC solar cells are and how they impact solar panel technology.

PERC can stand for either Passivated Emitter and Rear Cell or Passivated Emitter and Rear Contact. At its core, a PERC solar cell is simply a more efficient solar cell, meaning solar panels built with PERC cells can convert sunlight into usable electricity more easily. Solar panels made from PERC solar cells typically perform better than traditional panels in both low-light conditions and high temperatures. PERC technology boosts efficiency through the addition of a layer to the back of a traditional solar cell, which provides several benefits to the cell's production.

PERC solar cells are an exciting technology because of the efficiency gains they provide over standard solar cells. Additionally, moving 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.

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 back through 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 electron 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 of 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.

One of the biggest reasons why PERC technology can be so powerful is 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:

1. Application of the back surface passivation layer

2. 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.

Solar panels built with PERC technology allow for more energy-dense solar installations. This means that you can generate the same amount of energy using fewer PERC solar panels than you would with more standard 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 added benefit of bringing down the balance-of-system (BOS) costs for your solar panel installation. 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.

PERC solar cells are an exciting technology in the solar industry and can be a solution for property owners looking to maximize energy production with high-efficiency panels. In order to find the best solar option for you at competitive prices, register your property on the EnergySage Solar Marketplace to begin receiving custom solar quotes from local installers. If you are specifically interested in solar panels made with PERC solar cells, you can leave a note on your profile. Not all solar panel manufacturers use PERC technology, but certain installers may carry PERC products.