Welcome to our annual guide on the most efficient solar cells and panels. As usual we will first present the cells that convert the highest amount of light into electricity in lab conditions and then we will reveal the most efficient solar panels available in the market.
We are bringing a new twist this year in that we will also add the price per watt so that you can make a more informed choice about buying the top rated panels. You will find that most of them come at a premium price because of their superior performance. …
The highest efficiency CIGS panel in the market is the Solar Frontier SFK185s. It has an efficiency rating of 15 percent. This may feel low but the panel outperforms all other panels in low light conditions. This is because thin film technology is known to perform better at low irradiance level.
How efficient are solar panels?
The year 2020 slowed down economic growth but the solar PV industry did show some resilience. Research and development in this sector, however, was a bit sluggish. The crystalline silicon technology is coming to a plateau where efficiency gains are diminishing, while other technology like perovskite and organic solar cells are seeing significant improvement year on year.
A couple of disclaimers have to be mentioned. Firstly, efficiency of solar panels or solar cells is not the best measure of the value you will gain out of them. It just means that they will produce more energy in the least amount of space.
Secondly, in our list we have excluded all the concentrated PV technologies, so without further ado here is a list of top 10 solar cells that have shown the highest efficiency in standard lab test conditions.
Video and transcript by kind permission Synergy Files
Which solar cells have the highest efficiency?
At number 10 we again have dye-sensitized solar cells but their efficiency over the last year has improved. They went from 12.3 percent to 13. The top rated ones have been produced in the Swiss institute EPFL.
At number nine we have the organic solar cells, which have a lot of investor interest as they could be game changing technology. They showed a very healthy improvement from 17.4 to 18.2 percent during the last year.
At number eight we have cadmium telluride thin-film cells, that remain stagnant at 22.1 percent. The research and interest in this technology has weakened, mainly due to the concern about the toxicity of the material, although the way it is encapsulated can prevent this hazard.
Next up at number seven we have the most widely sold solar cell, that is the polycrystalline silicon technology. It rose from 22.8 percent to 23.2 percent. It is Jinko solar that has produced these top rated poly cells.
At number six we have the thin film CIGS that remain at 23.4 percent, with no improvement in the last year.
Sitting at number 5 we have the perovskite, cells that have been dubbed as the next big thing in solar PV technology. They rose from 25.2 percent to 25.5 percent.
At number four we have the monocrystalline silicon. Another technology that is popular and in demand. The efficiency for them remained at 26.1 percent.
Gallium arsenide solar cells efficiency
The number three spot is occupied by gallium arsenide solar cells. They showed significant improvement last year and rose from 27.8 to 29.1 efficiency level.
The number two position goes to the tandem perovskite silicon cells that got up from 28 to reach 29.5 percent.
The number one spot is retained by the multi-junction cells that are commonly used for space application. They remain at 39.2 percent, a figure that is head and shoulders above any other PV technology …
The highest efficiency CIGS panel in the market is the Solar Frontier SFK185s. It has an efficiency rating of 15 percent. This may feel low but the panel outperforms all other panels in low light conditions. This is because thin film technology is known to perform better at low irradiance level. Its price per watt is $0.88.
Which is more efficient monocrystalline or polycrystalline?
The highest efficiency polycrystalline cell in the market is the Canadian Solar CS3W410P. It is 18.6 percent efficient and is very low in price, making it great value for money. The price per watt is only 0.62 dollars.
The heterojunction category, not to be confused with the multi-junction Panasonic, has now been taken over by REC and their panel the Alpha 380 watt has recorded a remarkable efficiency of 21.7 percent. It’s reasonably priced at 0.80 dollars per watt.
In the monocrystalline category Sun Power holds the crown. Its panel, the X22-370 holds the record for the highest efficiency of 22.7 per cent. It however comes at a premium and its price per watt is around 0.95 dollars.
How do bifacial solar cells work?
In the bi-facial category the LG395 N2T takes the cake. It has an outstanding efficiency of 24.3 percent when the bi-facial gain is included. Note that this solar panel needs to be installed on a stand and not flush against the roof to make use of its bi-facial feature. Its price per watt is 0.74 dollars. If it gets solar radiation only along one phase, then its efficiency value is 18.7 percent.
As for the multi-junction solar panels, Spectrolab has no close competitors. It still ranges supreme with its triple junction solar panel that is rated at 30.7 efficiency, namely the Spectrolab XJT Prime. Its estimated price per watt is 5 dollars.
Note that Ultra Devices that previously made gallium arsenide panels of up to 29.1 efficiency has ceased operations. So that was the list.
It has to be mentioned again that efficiency is not the best measure of the value you are going to get from a panel and it should be only considered when the space to install solar panels is limited.
How have solar panels cost and efficiency changed over time?
Video and transcript by kind permission Synergy Files
Which solar panels are the most efficient?
This is the first of a five part series in which we look at the technology advancement in the field of solar energy over the past 10 years. This will give you an idea of what technology we have at hand but also what we can expect in the future.
Each video will cover a particular area of solar energy technology. The topics are PV (covered in this post). Part 2 will be on inverters. Part 3 on batteries. Part 4 on orientation and integration technology, and Part 5 will be on solar thermal.
Let’s look at how solar PV technology has progressed over the last decade. This will help you understand what technology is obsolete and what is forthcoming.
Increasing solar panel efficiency
During the last decade solar PV panels have evolved significantly. Over that time, polycrystalline panels have overtaken monocrystalline to become the dominant technology in the market. They jumped from around 30% market share in 2010 to now 60% share in 2020.
The price of PV in that period has gone down precipitously from two dollars per watt to just 32 cents per watt. PV panels are being manufactured all around the world, although china is still producing more than 50 percent of the panels in the market.
What is the largest solar panel available?
The efficiency of the panels over time has improved consistently at the rate of 0.5 percent per year for both mono and polycrystalline. 10 years ago panels with power rating of 80 to 120 watts were the most commonly found. Today, a single solar panel with a power rating of 410 watts can be purchased.
The technology has slid towards larger panels because it allows for more competitive pricing and more efficient generation per unit area. Overall, the performance has improved, not only because of cell efficiency enhancement but also with better internal electrical connections.
One of the problems that has been highlighted over the last decade is the potential induced degradation or PID in solar panels that can result in power loss of up to 30%. Let’s explain PID or potential induced degradation:
As the panels have become larger their internal voltage has increased. This has led to an increase in the voltage difference of the panels with respect to the ground and resulted in harmful stray currents. The latest panels are addressing this problem by taking into account the creepers and clearance.
They are improving the lamination process and are better at isolating the panel from the frame. Note that older panels that may not have been designed to higher isolating standards can be aided by the installation of an anti-PID device.
Another technology that has surfaced over the last decade is the cut-cell technology. As the name suggests, this means that the PV cells are cut in half.
This has multiple advantages, such as:
- the lowering of resistive currents
- improvement of cell power
- higher stress resistance
- lower hot spot temperatures
- decreased opportunity for cell cracking.
PERC solar cell efficiency
The manufacturer REC was a pioneer of this technology but it has since caught on. 2014 marked the arrival of PERC technology in photovoltaics that has gone mainstream in six years. PERC stands for passivated emitter rear cell or rear contact.
It is the addition of another dielectric layer at the back of the solar cell. As a result it reflects previously unabsorbed light back into the cell for a second chance to convert it into electricity. With PERC 23 cell efficiencies have been recorded .
Which solar panels work best in low light?
Bi-facial solar cells that are capable of absorbing sunlight from both sides and produce electricity have been around since the 60s. However, the arrival of Perth technology opened up the opportunity for bi-facial solar panels to be developed at a large scale. They are most suitable for use in solar farm and agrophotovoltaics.
They can also act as a perfect energy collector for floating PVs. The bi-facial gain that is the additional output compared with the mono-facial modules can range from 5 percent to 20 percent.
Solar cell size
Solar cell size has also kept increasing to lower the production cost per unit power. From around 2010 suppliers began to move to 156 millimeters as the standard size and the older 125 millimeter wafers were more or less eliminated from the market by 2014.
Wafer suppliers in china then adopted 156.75 millimeter as the standard and this became the M2 wafer format. According to the international technology roadmap for photovoltaics, M2 represents more than 90 percent of the market for both mono and multi-crystalline wafers in 2018.
In 2019 manufacturers again began to diverge from this standard as they looked to maximize the active space in the module. To meet the industry’s demand for consistently higher power ratings, several major manufacturers have launched modules based on wafers measuring 158.75 millimeters, while a handful of high efficiency suppliers are working with the M4 format measuring 161.75 millimeters and it doesn’t stop there.
Solar cell wafer thickness range
Lastly, the cell wafer thickness is also going down. To date, the silicon wafer thickness has more or less remain at 180 micron. Any more thinning has resulted in cracking but now through a special diamond cutting wire the thickness can be reduced resulting in material saving.
The cost impact is estimated to be 1.5 cents per watt for every 10 microns of wafer thickness. An issue that has come to the surface in recent years is with regard to the polyamide back sheet in the panels. This layer of plastic at the back is witnessing cracking due to weathering even in panels that are only 6 years old.
To counter this problem TPD films are being used by tier 1 PV manufacturers which cost more. The TPD is the short form of three sandwich layers that is Tedler, Polyester and Tedler film. This sandwich layer is UV resistant and also resistant to humidity and vapor penetration.
If you’re thinking of buying panels today then to get the most value for your money you should look at larger panels with cut-cell technology and with higher dielectric strength rating to avoid any leakage of currents, and ask for solar panel certifications like the UL certification or IEC certifications mentioned below. Panels that are made by tier 1 suppliers may feel costly at the beginning but in the long run they will help you avoid many potential problems.