Types of Solar Panel Designs
Solar panel modules come in a variety of 'designs'. The untrained eyes may be befooled into thinking that they are for style, but for what they truly are, the variations in designs are often a matter of the technology used in their manufacture of the panels than of mere aesthetics. New trends and innovation in the solar module industry quickly follow the latest ones in rapid succession, often times displacing them. The reason being that manufacturers are constantly pushing back the limits of efficiency of their module offerings. In fact, all the top manufacturers have ceased offering panels manufactured from the traditional technologies. There is significant competition between manufacturers, especially the premium brands, in this respect. The efficiency of a solar panel is how well it performs its function of converting sunlight into electricity. The latest solar panel technologies - or designs -, though expectedly far more expensive, come with the highest efficiency ratings.
The traditional technology used in the manufacture are the polycrystalline and monocrystalline technologies. Between the two, monocrystalline is the superior cell technology. Monocrystalline cells are more efficient because they are cut from a single pure crystal ingot. However, because they cost more to manufacture, polycrystalline panels became more popular even though they are inferior to their monocrystalline counterpart. With the drop in manufacturing costs, many manufacturers now use the monocrystalline technology. In fact, even though poly cells are still widely used and very reliable, the top brands have altogether stopped issuing polycrystalline panels and many mid-grade manufacturers are following suit.
By and large, these new solar cell technologies are upgrades on the traditional monocrystalline module technologies. They are listed below in ascending order of efficiency:
PERC - Passivated Emitter Rear Cell
Multi Busbar Cells
Dual Glass Panels - Frameless Double Glass
HJT - Heterojunction Cells
IBC - Interdigitated Back Contact Cells
1. PERC - Passivated Emitter Rear Cell
This is the traditional solar cell technology. PERC stands for Passivated Emitter and Rear Cell or Passivated Emitter and Rear Contact. In PERC cells, a dielectric passivation layer is added to the rear of the cell. The extra layer is to allow more sunlight to be captured and turned into electricity with the goal of increasing the efficiency of PERC cells over traditional solar cells.
PERC technology was invented by a Canadian scientist, Martin Green.
PERC technology comes in two different types, the n-type and the p-type PERC cells. The main difference between p-type and n-type solar cells is the number of electrons. In a p-type cell, the silicon wafer is doped with boron, an element with one less electron than silicon. This makes the cell positively charged. In an n-type, the cell is doped with phosphorus which has one more electron than silicon, making the cell negatively charged.
N-type cells return higher efficiency values than their p-type counterparts. They are also not affected by light-induced degradation unlike their p-type cells.
The International Technology Roadmap for Photovoltaic (ITRPV) predicts that the market share of p-type monocrystalline solar cells will hold around 30% through 2028, while their n-type counterpart will increase to about 28% from barely 5% in 2017. This correlates to the industry demand for more high-efficiency modules so solar buyers can expect more n-type designs entering and disrupting the mainstream.
Trina Solar, Winaico, Q Cells, LONGi Solar, Risen and JA Solar all use advanced variations of the PERC technology in the manufacture of their panels.