Yash
One of the important aspects of any solar power system is the efficiency of the solar panels.
It plays an important role in determining the overall profitability of the system.
So, looking for the efficiency of the solar panel is important when you are purchasing it for use.
The efficiency rating of any solar panel reflects its ability to produce electricity.
In this post, we’ll discuss the most efficient solar panels available in the world market in 2021.
But before this,
Let’s clear and understand some basics:
What is solar panel efficiency?
The ability of the solar panel to convert the proportion of sunlight into electricity
For instance, a solar panel with an efficiency of 15% will convert 15% of the sunlight into electricity for running our electrical appliances.
The efficiency of any solar panel is measured under Standard Test Conditions (STC):
- Temperature: 25 degree Celsius
- Sunlight: 1000 w/m^2
- Air Mass ratio: 1.5
(Air Mass is the path length that sunlight has to pass through the atmosphere).
When sunlight passes through the atmosphere, its power gets reduced due to absorption, reflection, and scattering by air, dust particles, and water molecules.
The Air Mass ratio is the ratio between the path length that sunlight has to cover to the path length when the sun is directly overhead).
The efficiency of the solar panel is calculated by measuring the maximum power rating of the given solar panel and dividing it by the product of its area and solar radiation of 1000 W/m2
It can be shown and written as:
In simple words, an efficient solar panel produces more current.
Factors affecting the efficiency of solar panels
Efficiency mainly depends on the following factors:
1) Purity of Silicon
Most photovoltaic cells are made from silicon crystalline wafers and these wafers are of 2 types:
(i) Mono-crystalline and (ii) Poly-crystalline.
Mono-crystalline silicon wafers are more efficient than poly-crystalline ones.
2) Type of silicon material (P-type or N-type)
- When silicon wafers are treated with traces of Boron, it becomes P-type silicon
Whereas,
In N-type silicon, the silicon wafers are doped with traces of Phosphorous.
When these are joined together, we get a P-N junction, the basic function of silicon solar cells.
This junction creates an electric field.
When light falls on this junction, the electrons get excited and get free and start moving in the opposite direction of the electric field, constituting the current.
When the underlying substance or base is P-type silicon and an ultra-thin layer of N-type silicon is pasted on it, it becomes a P-type silicon cell
And
when is done the opposite, we get N-type silicon cells.
The N-type silicon cells are more efficient than the P-type ones as they offer better temperature coefficient and low light-induced degradation but are costlier than P-type silicon cells.
Other important factors
- Interconnection of cells
- Color of the panels (Blue or Black): Black color absorbs more heat than other colors. Hence, decreases the performance of the solar panels.
- Corrosion and breaking of the connection between the cells
- Failure of by-pass diodes
- Metal-ion migration
- Aging of solar panels
5 years back, we use to see less efficient solar panels than what we have today.
The increase in the efficiency of the panels over time and decrease in the per-watt cost of the panels have further improved the profit margin of the solar power systems and have it is now financially rewarding like never before.
More and more people are now interested in installing solar on their rooftops.
Most solar panels that are available in the market have efficiencies in the range of 15% to a little over 20%.
7 most efficient solar panels are:
1) ) SunPower X series: (22.2%)
Sunpower is a USA-based solar company that has a rich solar experience of more than 35 years. It has headquarters in Silicon Valley.
SunPower’s X series 360 watts panels are top of the list with the maximum average efficiency of 22.2% which means that you’re going to get more current even in smaller spaces.
The solar panels are durable as these are based on a solid copper foundation, making them impervious to corrosion that attenuates panel degradation.
2) LG Neon 375 watts: 21.7%
This South Korean giant is second on the list with its 375 LG Neon solar panels with a maximum efficiency of 21.7%.
It is based on Mono-crystalline/N-Type solar technology that gives you enhanced performance on sunny days.
The LG solar panels will produce at least 90.8% of the Pmax in the 25th year.
Let us calculate the efficiency of the panel through the formula stated above:
The given parameters are:
- Pmax under STC: 375 watts
- Dimensions of 375-watt LG Neon Panel: 1700 mm x 1016 mm x 40 mm
We know that
Efficiency = {P max under STC/Area x 1000} x 100%
= {375 watts/(1.7 x 1.06 x 1000)} x 100%
= 21.7%
Wow!
we have found the right value, it tallies what is given on the LG company website.
Let’s see how the solar panel degrades over its lifetime.
The company states that its output warranty for the 1st year is 98% of P max and then degrades at the rate of 0.3% every year till the 25th year.
In the 1st year, degradation (2%) is the maximum due to light-induced degradation (LID).
Let’s see how degradation happens over time:
You can see that in the 25th year the panel is going to produce 342 watts that are over 9o% of Pmax (375 watts).
3) REC alpha series: 21.7%
REC Solar is a Singapore-based company and its alpha series 380 watts solar panels are 21.7% efficient.
These panels are designed with Hetero Junction/ N-Type solar technology that has reduced the Light Induced Degradation (LID) to zero, making them produce at least 92% of Pmax in the 25th year which is an industry best.
4) Longi Solar: 20.9%
Longi Solar is a Chinese company and its 455 watts solar panels are 20.9% efficient and are based on bi-facial technology, enabling them to produce electricity from both sides.
5) Canadian Solar: 20.4%
It is a Canada-based company that is producing 420 watts of solar panels using high-density Mono-PERC (Passivated Emitter and Rear Contact) technology that maximizes the light absorption area of the panels that improves their efficiency.
6) Panasonic 340 N Hit: 20.3%
Panasonic (Japan) solar panels are 6th in place in terms of efficiency. Its solar panels are based on heterojunction technology (HJT) and are having the lowest temperature coefficient (-0.258%) in the world.
(The temperature coefficient is the percentage decrease in Pmax for every degree rise in the temperature beyond 25 Degree Celsius).
7) Solaria Power XT: 20.2%
Solaria is a USA (California) based company.
These monocrystalline solar panels have fewer gaps between the cells, increasing their efficiency and making them on the list of the top 7 most efficient solar panels in the world.
(Find out how much you can save with solar using my latest and comprehensive solar feasibility spreadsheet.)
Although these have higher efficiencies, they are costlier than other less efficient solar panels available in the market.
Why efficiency matters?
In technical terms, a more efficient solar panel will produce more current and you get your fans and lights running smoothly for decades.
In financial terms, a more efficient panel will save you more grid units and will pay back faster.
when you see high-efficiency solar panels the following features are generally common:
- High-grade solar cell design technology
- Better temperature coefficient
- Less degradation over time
- They require less space
(The efficient solar panel generates more current per square meter and therefore occupies less area on the rooftop compared to that of a less efficient one).
Therefore, highly efficient solar panels are a good option for people having limited shade-free rooftop areas.
External factors affecting the efficiency of solar panels
Let us discuss the important factors:
1) Amount of sunlight
You’ll get a different amount of sunlight during the day. It is minimum during sunrise and sunset and maximum at the noon. Also, cloudy weather and humidity obstruct the sunlight and your panels are going to produce less current.
2) Temperature
It is contrary to the belief that solar panels produce more current at high temperatures.
Rather
The opposite is true, panels perform better under low temperatures below 25 degrees Celsius.
3) Solar panel orientation
A wrong tilt can affect the output from the solar panels.
Therefore, the solar panels are placed in the right direction and angle to get maximum sunlight.
4) Location
The equator gets more sunlight than any other location. Therefore, the more you are away from the equator, the less current you’re going to get from your panels.
5) Time of the year
we know that earth is revolving around the sun in an elliptical orbit. During summers when the earth is near to the sun, we see summers and get more sunlight.
As earth starts receding away from the sun, we witness winters and we get less sunlight.
6) Dust and dirt
The dust and the dirt accumulated on the solar panels block the sunlight and affect their efficiency.
Therefore, the places with more dust and dirt, the reduced current output is the problem.
What should be your choice?
Although, efficiency is the major criterion when purchasing solar panels but the cost of the panels is also the point of concern.
How do decide which one to buy?
Simple!
Take 2 panels of your choice and write down their efficiencies and the cost on the piece of paper.
If the percentage increase in the efficiency is more than the percentage increase in their prices, then go ahead and buy the high-efficient panel.
While if the opposite happens,
Then the less efficient solar panel is a suitable option.
You can see that these top 7 solar panel producers are using innovative technologies for improving panel efficiency.
Now it is a matter of choice whether you prefer one over another.
Well,
It depends on several factors like your budget, energy needs, location, availability of shade-free areas, and after-sales service.
And
The panel that fulfills all the above requirements, giving you value for money, should be your choice.
Over to you,
What is your choice and why?
Please share your views in the comment section listed below.
