As our society?s power consumption is growing by the minute, the question of how much usable energy can actually be harvested from a solar project is something any potential investor will most definitely want to know. It should come as no surprise that manufacturers have their R&D teams rack their brains over how to increase PV panel efficiency. The math is pretty simple: the more energy your solar project is able to convert, the less time it will take before your initial investment pays off and you start seeing real savings.
Let’s not forget, of course, about other considerations, such as PV panel location, their orientation, maintenance quality, or unpredictable weather patterns. Efficiency remains, however, among the key elements that allow distinguishing between a Tier 1 panel and the rest.
Solar panel efficiency ? main facts
While solar panel efficiency is relatively easy to define as the amount of sunlight that gets converted into usable energy, the factors that determine it are a little less straightforward.
In order to measure the conversion efficiency of the whole solar panel, we need to know, first of all, the efficiency of the photovoltaic cells it is built from.
What influences PV cell efficiency?
- The material the cell is made of.
- Its structure and design.
Among the semiconductor solar cell materials, silicon is the most traditional and the most widely used. Why?
On one hand, it is easy and relatively cheap to produce, which plays a great commercial role in making solar panels commercially attractive.
On the other hand, its crystalline structure ? also called lattice ? is highly organized, which allows for a better conversion of light into electricity.
Difference between n-type and p-type silicon solar cells
Not all silicon solar wafers are the same, though. The two most common distinction is between the n-type and the p-type silicon cells. The ?N? and the ?P? letter refers to whether a given cell is built on a negatively or positively charged silicon base.
In the case of the p-type solar panels, the wafer base gets positively doped with boron while its top ? negatively doped with phosphorus.
The opposite technique is used for the n-type cells, and the negatively charged part is the cell?s base. Both methods allow for the formation of a p-n junction, which, in simple terms, means that the electricity can flow through the cell.
Now that we have the scientific part covered, let?s ask ourselves if there are any differences between the n-type and the p-type cells when it comes to their business potential.
Efficiency
The first one will definitely be their efficiency and the consequent yield. Speaking of solar panels in general, the buyer should expect their efficiency to be somewhere between 15 to 20+ range, n-type panels placing themselves on top of the ladder.
Why do n-type solar panels have higher efficiency?
It has to do mainly with the so-called boron-oxygen (BO) defect, which is responsible for the degradation of the carrier lifetime of B-doped silicon materials.
This problem, common in the p-type solar cells, fortunately, does not bother the phosphorus-doped n-type cells, making them more efficient in the long run.
The n-type cells are also immune to another negative effect called the Light Induced Degradation (LID). LID ? also referred to as ?thermal shock? ? can be defined as a difference between the STC-certified rating of a solar panel and its real performance and quality at the initial stages of exposition to the sun (the very first few hours).
Cost
Even though the first solar cells, manufactured back in the 1950s, were of the n-type, they were quickly overshadowed by a growing demand for p-type wafers. How come?
Let?s not forget that at the early stage of its development, solar technology found use principally in space applications which meant extended exposure of solar panels to different kinds of radiation. The p-type cells simply proved to be much more resistant to that radiation than the n-type ones.
As solar panels became more and more popular, the p-type silicon material found a constantly growing market. Not only were different versions of p-type panels developed but their massive production started to benefit from economies of scale. As the unit production cost of p-type wafers got progressively lower, their final price became much more attractive than that of the n-type wafers.
Today, however, the situation is changing. Solar technology has found new uses and panel efficiency is becoming more important than ever. Customers want to see real savings fast, which means there is a lot of market pressure for better conversion results.
In this new reality, n-type cell technology is gradually coming out from the shadows.
According to the ITRPV forecast, its market share is expected to grow substantially (to about 28%) before the end of this decade.
Source: International Technology Roadmap for Photovoltaic (ITRPV), Ninth Edition, 2018.
One of the companies participating in the race for higher efficiency is Jinko Solar (NYSE: JKS).
Jinko Solar ? company overview
Jinko Solar ? a Chinese manufacturer founded in Shanghai in 2006 ? is currently one of the world?s largest and the most innovative solar product suppliers, with a market share of about 14.3%.
It has 12 production plants, over 30 international sales and service offices, 25+ warehouses, and 25.000 employees that help to attend to the company?s 3000 customers in 160 different countries.
Jinko Solar?s integrated annual capacity is 20 GW for mono wafers, 11 GW for solar cells, and 25 GW for solar modules.
Based on the Q1 2021 financial highlights, this year has brought Jinko Solar the following commercial results so far:
- total revenues of US $1.21 bln,
- gross profit of US $207.3 mln,
- net income of US$33.7 mln,
- quarterly shipments of 5,354 MW (4,562 MW for a module, 792 MW for cell and wafer).
The company puts many of its stakes on innovation and R&D. It already prides itself on almost a thousand authorized patents, 94 of which are invention patents. With over 900 people employed in R&D and 1.124 billion yuans expenditure in that area, it is no wonder that so many great ideas are coming from their kitchen.
Jinko Solar?s product portfolio is well-diversified and based on several different technologies. According to the company?s claims, it is the n-type technology that is showing the most promising results in terms of panel efficiency.
Jinko n-type monocrystalline cell
Well aware of its potential advantage over the p-type solar cell, Jinko Solar has put great effort into optimizing the n-type monocrystalline cell and thus maximizing its efficiency.
The key solution has proved to be an increase in the bifacial factor along with optimizing the operating temperature.
The company has also been testing the behaviour of HOT 2.0 cells when applied the passivation contact technology. It has been found that such a technique ?updates the Micro-nano tunneling through the oxide layer and carrier selective lamination of microcrystalline silicon thin films on the rear side.
This advanced structure contributes to better passivation performance and electrical conductivity, increasing the cell efficiency and power generation performance?1.
The Jinko Solar N-type TOP HOT2.0 cell is obtaining record-breaking results in terms of conversion efficiency. When tested on a large-area project in January 202, it marked 24.9%, a number never seen in the solar industry before and an improvement from its previous record of 24.79% from July 2020.
Both results have received official and independent confirmation from the German Institute for Solar Energy Research (ISFH).
Thinking of purchasing a Jinko N-type solar module? They are being commercialized as TIGER N-Type Series. At the moment, two different panel sizes are available for the EU market, both of them manufactured with the use of Tiling Ribbon Technology:
- 120 cells (6×20), 1692×1029×30mm / 19kg / 60 TR
- 132 cells (6×22), 1855×1029×30mm / 20.8kg / 66 TR
The smaller panel promises energy conversion of 355-375 Watt, while the larger one, that of 390-410 Watt.
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The race for higher efficiency of solar panels is far from over. Quite recently (June 2nd, 2021) another top player in the industry ? LONGI ? broke the 25% barrier, claiming 25.21% for N-Type TOPCon, 25.02% for P-Type TOPCon, and 25.26% for HJT modules. It might not seem like a big jump from Jinko?s achievement but in our energy-dependent society, every Watt of clean power counts.
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