As we all know, photovoltaic modules are made of silicon wafers.
Cell types depend on the transformation process: monocrystalline or polycrystalline wafers can be produced. Advances in the solar industry have developed technologies increasing panels’ efficiency. Today, you can get polycrystalline and monocrystalline panels in the market, cell types can be standard, PERC, half cut cell, BIPV, etc.
What are the differences between standard silicon wafers and PERC technology?
The features that we are used to with conventional cells are the following:
| Mono | Poly |
| The first technology developped Slow melting process Its manufacturing implies a high energy cost It is slightly more efficient Its overall manufacturing process is slower | Developped later Fast melting process Its manufacturing is cheaper It is slightly less efficient Its manufacturing is faster It is navy blue |
| They behave better in cold climates, with the presence of storms or fog, The cell absorbs more solar radiation but has a higher chance of overheating. | They have better behaviour in hot climates, the cell absorbs heat at a higher speed and is less prone to overheating. |
How does it work?
Light is an electromagnetic wave that can have different wavelengths. Depending on the wave length, the penetration range of the silicon wafer is different.
Short wavelength is easily absorbed by the atmosphere, so the remaining amount can only penetrate the emitting layer, generating electrons, that is, electric current.
If the wavelength is longer it will reach the cell with a high energy level, penetrating the emitting layer, the base layer and even reaching the lower layer. This generates a loss of energy that cannot be adsorbed by the cell.
What is PERC technology?
The word PERC is the acronym for Passivated Emitter Rear Cell. This technology can be summarized by the application of a reflective layer to maximize radiation and have a smaller margin of energy loss. This layer is made of passive dielectric material and is located between the lower aluminium layer and the silicon base layer.
How does this layer work?
This dielectric material blocks the passage of light through the lower layer, we can generate accumulation of electrons between the base layer and emitting layer. In other words, what PERC cells generate is a use of long wavelengths that are not used with standard cells.
The passivation of the dielectric material prevents electrons from penetrating into the aluminium layer, thus allowing better circulation between the base and silicon emitting layers only.
It is also important to note that PERC technology has a positive impact on the temperature coefficient, since there are longer wavelengths that cannot penetrate directly into the lower aluminium layer, but are reflected by sending them outside the panel and are therefore less vulnerable to overheating than with standard cells.
Currently, the manufacturer Longi holds the record of efficiency in PERC monocrystalline cells, which is why Eco Green buys its cells from this company to produce its panels, since quality is the most important thing for us.
Contact us if you want more information about our products, our international team can provide all the support you need.
