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What’s New in Solar Panel Efficiency

All Aboard the Efficiency Hype Train

Efficiency is key when it comes to solar panels. It defines just how much a solar photovoltaic system, can convert solar energy into electricity, how fast and for how long. Panel efficiency has generally been a limiting factor for solar panels historically, but with advances in technology, modern panels are becoming more and more efficient and also more affordable. This is good news for consumers trying to switch to solar energy, yet it can also be a source of information overload and lead to ‘paralysis through analysis.’ Constant updates to a technology mean that consumers may end up waiting for the next best thing to come out before making a decision on what to buy, leading to indecision and indecisiveness. So, as a prelude to this article, which will cover what is new in the exciting world of solar panel efficiency, we will first talk about why you need to make a decision sooner rather than later and why waiting to adopt the newest technology may end up costing more in the long run. But that said, solar energy in Australia and in the world over is going to be seeing some revolutionary changes in efficiency.

Why Switching Now is Better

It is something of a recurring trend with cell phones, cars and computers – modern manufacturers make things that can last a lifetime and then try to one-up themselves annually. The technology market has developed a trend where a piece of technology will be upended within a year by either rivals or its own manufacturer. This is done in order to reel in as many sales as possible. Every year, a new iteration of smartphone X will hit the market, and the versions of flagship devices keep on getting more and more obnoxious names. My-Phone Max Pro Plus Ultra will have more features and be more stuffed to the brim with tech than My-Phone Max Pro Plus. The same holds true for computers, their processors and graphics cards. Today’s king is tomorrow’s layman and today’s layman is tomorrow’s pauper. Automobiles have also followed a similar path. A new model of a high-end luxury sedan with incremental improvements is pushed out every year and demands that customers upgrade. This has had a wonderful effect on modern consumer items, making them more competitive and also improving technology at a pace not seen before. Yet it has also led to a lot of disposable gizmos that people pay a premium only to use for a year, before looking for the next best thing. Blatant consumerism comes to mind, and its effects on the environment cannot be ignored. Yet this is the undeniable side-effect of improvements in technology. As improvements occur faster and faster, people will look to purchase more and more, causing companies to try and make more improvements.

The solar industry is currently in the middle of a boom, both in terms of its scale of adoption and also in terms of its quality. Though advancements in solar modules are not taking place as rapidly as those in the smartphone world, consumer paralysis is very much a reality, when you look at technology that is just around the corner. It is not a foregone conclusion that a customer may choose to wait until so and so improvement hits the market or until so and so technology is up for sale. This becomes an even greater possibility when we consider the fact that solar panels are made to last 25-30 years. Unlike smartphones, you probably will not be considering a new solar panel next year, if you buy one now. For many a customer, this may end up being all the more reason to wait for the next best iteration before investing. This is a bad idea.

Solar technology is markedly improving in terms of efficiency and affordability. This is true, but new technology also comes with growing pains and no small amount of uncertainty. Even if newer technology is made available to the market, it will still be some time before all its shortcomings are realised. The same is not true for technology that has been around for 25 years. It is tried, tested and true. And in 25 years, when your solar energy system is up for replacement, you will be well placed to take advantage of the best technology of that time in all its glory. Another point to consider is the cost of waiting vs. the cost of adopting now. Let’s assume that an average consumer (we’ll call them A) is thrifty with expenses and not an ‘early adopter.’ Said customer (A) would want to wait for a piece of tech, say a new solar panel, to hit the market, and then wait for its reviews to come out before committing to a purchase. These are reasonable assumptions, but with solar panels, you would have to wait a few years to know how they’re going to fare over the long run. Let’s say our consumer (A) decides to wait two years to see how the new solar panels will play out before buying them. Well, your average 6-10kW solar panel in Australia will pay for itself in 3 – 5 years. Now Let’s say there is another customer (B) who was deciding whether to buy a panel alongside A, and unlike A, B decided to buy then and there after doing their due diligence. By the time A decides on whether the newer panels are worth purchasing or not, B’s panels will be halfway to paying for themselves. So, before we get into the future of solar panels, both near and distant, and how amazing they’re going to be, one thing to keep in mind is that if you or anyone you know is having trouble deciding whether to buy now or wait for the next incremental improvement, now is the answer. Buy now, and you can always upgrade later. But start saving today.

most efficient solar panelsThe Narrowing Gap Between Panel Efficiency.

The most efficient solar panels belong to American companies, and they have held the top spot for a long time. This is not to say that European and Chinese panels are slouches. On the contrary, some of the best, longest lasting and most durable panels are European and Chinese. There is more to solar panels than just efficiency, but this article will focus only and only on efficiency. Therefore, we will be looking at this singular aspect of solar panels. When shopping for solar panels, customers are best advised to keep efficiency, durability, lifespan and cost in mind. Just because a panel is efficient does not mean it will hold its efficiency for the duration of its life. Similarly, physical durability does not always translate into an increased lifespan. Though the former goes a long way in ensuring the latter, it is not the only deciding factor. One can make the argument that each of these factors is just as important as the others, and it will be difficult to choose one factor above the others. For instance, is it more important for a panel to be efficient, or is it more important for it to hold its efficiency over its 25+ year lifespan? Or vice versa? The answer is that panels must be a balance of all these factors, each more or less equally important. Nonetheless, we will look at each of them in turn in a series of articles, starting with efficiency.

Solar panel efficiency has been increasing steadily in the past few years, and is still on the rise. The gap between panel efficiency in 2021 is small now than ever before, with the maximum hovering around 22.80% at 425 W of output. As it stands, there are at least 10 tier 1 solar PV system manufacturers with panels rated at over 21% efficient. The competition for efficiency is now in decimal points. You will find that many of the top ten most efficient solar panels are represented by Integra Solar. But we don’t simply look out for efficiency. We look at all the key features that a solar PV system must possess before making a recommendation to our customers.

But while we’re harping on about efficiency, we might want to explain what we mean by the term efficiency and how it is measured. In this article, we will look at the following:

  1. How is Solar Efficiency Defined?
  2. How is Solar Efficiency Calculated?
  3. How do Different Solar Cell Types Compare in Efficiency?
  4. Where do Solar Panels Stand in Terms of Efficiency in 2021?
  5. How Does Spec Sheet Efficiency Translate into the Real World?
  6. Are High-Efficiency Solar Panels Cost-Effective?
  7. Which are the Best High Efficiency Panels on the Market?

Defining Solar Panel Efficiency

Solar panel efficiency is measured by calculating how much of the sunlight that touches every portion of a panel is successfully converted into electricity. The amount of sunlight that a solar panel can convert into electricity, from the amount it receives is called efficiency The less sunlight a panel wastes and the more it can successfully convert, the more efficient it is said to be. Conversion of sunlight into electricity is referred to as the photovoltaic effect. In this process, semiconductors are used to separate sunlight from photons.

Solar panel efficiency ratings are given on the percentage of light converted to electricity by the panel. So, our high-efficiency panels convert 22% of sunlight received into solar energy. This means they are 22% efficient i.e., they convert 22% of the sunlight that touches them into electricity.

Calculating Solar Efficiency

So how exactly is efficiency calculated? When you go to buy a solar panel, you’ll get a datasheet showing the efficiency rating of each panel. What this sheet will not tell you is how efficiency is calculated.

Solar efficiency is calculated by testing the panels at a constant temperature of 25 degrees centigrade and with 1000 watts of solar irradiance. Solar irradiance refers to the amount of sunlight hitting the solar panel at a given time. These conditions are called STC or Standard Test Conditions.

The formula used to determine solar panel efficiency is as follows:

Efficiency = Power rating of panel / (Area of panel x 1000W/m2) x 100

So, we divide the power rating of the panel by the area of the panel times the irradiance, times 100.

One thing to keep in mind is that solar panels on a rooftop will not operate under standard test conditions. Environmental factors will affect the solar irradiance that reaches your panels and also the temperature at which your panels operate. This will indefinitely affect the efficiency of a solar panel systems.

Comparing the Efficiency of Various Solar Cells

Solar panels are made of a number of silicon solar cells. These cells are wired together using copper wiring. Over the years, different companies have used different techniques to increase the efficiency of their solar panels. RECOM, for instance, uses a new and advanced shingle design to increase both the efficiency and the durability of their solar panels. Modern companies are extensively involved in solar research, finding newer bandcenter ways to break through the 22% ceiling. RECOM’s newer panels feature all-black designs. In designs like these, you can barely one cell apart from another. This is because the connecting wires between cells are hidden, giving the panel a distinctively clean look and also increasing efficiency. In addition to this, Chinese companies (many of which are represented by Integra) have also begun pioneering bifacial modules. This technology exposes both the front and rear ends of the solar panels, thereby increasing the combined surface area of a solar PV system. Bifacial modules absorb solar irradiation from both sides, increasing their efficiency in comparison to traditional panels.

The solar industry has seen a massive uptick in research, and newer and more advanced panels always seem to be just around the bend. Nonetheless, the most efficient panels all have something in common in 2021: they exclusively make use of monocrystalline silicon cell technology. Polycrystalline cells are cheaper, but less efficient, and for this reason alone, we cannot recommend them for long term use. The following advancements in monocrystalline technology have allowed companies to exceed 20% efficiency rating:

PERC Solar Cells

PERC, or Passive Emitter and Rear Contact were developed in Australia in 1983. PERC cells use a monocrystalline structure that has a reflective back layer. This layer allows photons that have been wasted to bounce back through the panel and be reabsorbed by the silicon wafer for electricity production. Generally speaking, PERC cells add 1% efficiency to the solar energy system. This may seem small, but when you take into account that they are very inexpensive to manufacture, they suddenly become worth the added effort. Today, companies compete for efficiency gains as incremental as 0.50%, so a 1% improvement provided by PERC panels is a must have. Especially in light of the low costs associated with it.

HIT Solar Cells

Heterojunction with Intrinsic Thin Layer cells, also referred to as HIT cells are made using monocrystalline solar cells sandwiched between amorphous thin-film silicon. Amorphous silicon uses different spectrum of light than the monocrystalline layer. This allows a solar cell to utilise as many spectrums of light as possible. This increases solar panel efficiency slightly, as more solar power can be extracted from it. HIT solar panels consistently rank among the highest rated solar panels in terms of efficiency, coming at around an impressive 21.9%.

Multi-busbar Technology

Some manufacturers use super thin wafers to collect electricity generated within solar cells. This reduces shading on adjacent solar cells, increasing overall efficiency.

Split Cell Technology

Some solar cells are split in half. This reduces heat resistance in the individual cells and results in small efficiency gains. Heat reduces efficiency, and since solar cells operate in mostly in high temperature areas, reducing temperature is a key aspect in improving efficiency. Split cell technology results in efficiency gains as much as 21%.

Solar Panel Efficiency in 2021

A survey conducted by the NREL (National Renewable Energy Laboratory) found that most solar panels on the market have an efficiency rating between 15 – 20%. This trend is slowly beginning to change, however, as more and more solar manufacturers are making panels with quoted efficiencies over 20%. Moreover, the gap between solar panel efficiency has been steadily narrowing, and over ten large manufacturers now have panels with efficiency ratings over 21%. The gap between the efficiency ratings of the world’s leading solar panels brands has reduced drastically over time. Today, over twenty brands have solar panels with a rating of over 20%.

Tier 1 Chinese Solar Panels: High Efficiency at Reduced Costs

While European and American companies have staked claims in the higher efficiency areas of the solar industry, Chinese companies like Jolywood have managed to marry both efficiency and affordability like few others in their solar energy systems. Premium panels tend to have higher efficiency ratings, but Chinese panels have competitive ratings, but at lower costs. Overall, these panels do not take a massive hit in terms of system efficiency, but they come in around 20% cheaper than the more premium panels.

Also, the negative connotations attached to Chinese products do not hold true for solar panel manufacturers. China has some of the most advanced and largest solar panel production facilities in the world. These facilities supply panels to countries all over the world, like Australia, America India and others in Europe, Africa and Asia. Jolywood and other Chinese manufacturers produce over 12 and in some cases 16 gigawatts (GW) of solar panels per annum, while companies producing the single most efficient panels only come to around 2.5 GW per year.

If anything, this should go to show just how much price factors into a consumer’s decision to purchase a particular panel. Sacrificing 0.5% of efficiency may be worth it if you can shave a few hundred dollars off your overall price. This begs the question if the topmost manufacturers will be able to hold onto their share of the market, as more and more affordable, if slightly less efficient, Chinese products find their way into the market. Some of the top tier manufacturers make the most expensive and most efficient panels in the world, but the question is, are they worth it? Will they hold onto their share of the market?

Solar Panel Efficiency in Real World Conditions

As we said before, there is a difference between solar panel efficiency in the real world and in the spec sheets. In the real world, solar panels seldom operate in conditions that match the standard test conditions. Inconsistencies in temperature, cloud cover, changes in solar irradiation and precipitation can alter the performance of a solar energy system. Let us take a look at what factors affect performance and how. Also, it is important to keep in mind that durability and resistance to microfractures is essential when considering purchasing solar PV systems. Durability is what will ensure that a solar PV system lasts and holds as much of its efficiency as possible over the course of its lifetime.


Solar panels, despite the fact that they make energy from the sun, operate better at cooler temperatures. The irony should not be lost on anyone. Nonetheless, it is a limitation of our technology that it operates better in cooler conditions. This is because as solar panels get hotter, current increases, but voltage decreases. This reduces the overall output of the panel as well. This means that solar panels are actually more efficient in the winters, even when they are getting less sunlight and making less power overall.

Something to keep in mind is that temperature here does not refer to atmospheric temperature that you might see on your weather app. It refers to the temperature of the solar panel, and more specifically the solar cells within the modules. Now this is directly related to atmospheric weather, as atmospheric conditions will determine what the temperature of your panels is by influencing how much sunlight and heat, they receive.

Temperature coefficient refers to the amount by which output of a solar panel reduces above 25oC. A lower temperature coefficient means that the output of the panel is less affected by extreme heat. A higher coefficient means that the panel is more affected by heat. More efficient panels tend to have a lower temperature coefficient.

Dirt, Dust, Debris and Precipitation

The more foreign particles that accumulate on your solar panel, the more they will be affected. Foreign particles block sunlight from reaching the panels and reduce efficiency. Similarly, snow, if allowed to build up, will drastically affect solar panel performance. Since panels are usually installed at inclined angles, snow and rain can slide off them for the most part. Even so, snow can build up and accumulated stress can cause panels to develop microfractures, unless cleaned off at regular intervals. The best way to avoid these is to clean your panels regularly. This will keep them safe from external stresses and also keep them operating at maximum efficiency. The good news is that panels do not need to be cleaned ever week or even every other month. In fact, if you do a thorough enough job, once in six months should be more than enough.

Is Efficiency Worth the Price?

Before answering this question, a customer has to consider the following two points:

  • Space constraints
  • Available budget.

If you can’t afford a premium solar panel, then you can’t afford it. You’re better off with something you can afford. Therefore, we’re going to assume that our theoretical customer can afford both the premium, top-of-the-line panels and also more bankable panels from Tier-1 companies.

Finances being equal, space constraints have to be considered when purchasing a panel. The rule of thumb is simple. If space is constrained, then a customer should opt for a high efficiency panel. A premium panel will give you more bang for your buck in limited spaces, as they will produce more output in a limited area. If space is not an issue, then you’re better off purchasing a Tier-1 panel from a reputed company. Not only are these panels more affordable, but they’re also almost as efficient as the premium and more expensive panels.

As time goes on, it is becoming more and more difficult to make the case for premium panels because of their price. As the gap between panel performance narrows, the decimal points of efficiency are becoming less and less meaningful when their costs are kept in mind. The most important part of purchasing any panel is to get quotes from multiple sources and suppliers. Be sure to compare as many suppliers as possible so that you can make the best choice for yourself. The beauty of doing business with Integra Solar is that we give you the best options all in one place. Integra Solar offers our customers every choice of supplier, from premium panels like RECOM’s to more affordable yet equally capable ones like Jolywood. Our staff can take a look at your specific needs and tailor make a solar energy system to meet them.

Which High-Efficiency Solar Panels You Should Consider

To help you with purchasing a solar panel, we recommend going with one of Integra Solar’s partners. Our partners include:

All are renowned and top tier solar manufacturers with successful projects all over the world. Panels offered by these companies are not limited to being efficient, but are a combination of the factors that make solar energy systems a good investment, i.e., durability, longevity and efficiency over lifetime. Also, Integra Solar’s partners provide the absolute best warranties in the market.