✔ Some residential panels can convert up to 23% of sunlight into electricity
✔ The most efficient panel is 47.1% – but residential systems aren’t quite there yet
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The future of solar energy is looking bright. Known as “the sun”, this piping-hot powerhouse in the sky has bags of potential – we just need to work out how to make the most of it. Solar panels are doing an excellent job, but scientists are always trying to make them more efficient.
Thinking of switching to solar? This article will tell you all about the most efficient solar panels on the market, as well as our top tips for maximising your solar panels’ efficiency.
To receive free quotes for solar panels from a local installer, simply fill in this short form. We'll pass on your details to our professional suppliers, who will be in touch with quotes for you to compare.
What's on this page?
06 | How to maximise efficiency
07 | Finding an installer
What is solar panel efficiency?
Solar panel efficiency is a measure of how much sunlight a solar panel can convert into usable electricity. The majority of residential solar panels typically have an efficiency of 15-18%, although premium models can reach over 21%. Canadian Solar currently produces the most efficient solar panel on the market, at 23.8%.
Generally speaking, the two most important factors to consider when choosing solar panels for your home are efficiency and maximum power output (measured in kilowatts).
If you're thinking about taking the money-saving option and buying cheap, low-efficiency panels, think again.
Unless they're flexible solar panels, which come with their own unique benefits, you should check out our page on why cheap solar panels aren't worth the risk (and why it's wise to buy reliable, premium models from top brands, and keep them clean).
The most efficient solar panels in 2021
These are the most efficient solar panels for residential properties in 2021, complete with some bafflingly complicated names:
Solar panel manufacturer
LG NeON® R ACe
78-cell MBB Half-cell Module
PANDA Bifacial 60CL
Information updated in June 2021.
Here’s a bit more detail about the most efficient solar panels on the market, including maximum power, cell material, and warranties:
Canadian Solar’s BiKu CS3U-365PB-FG
BiKu CS3U-365PB-FG is a real mouthful, but it can reach up to 23.80% efficiency and a maximum power of 380 watts. Made of polycrystalline cells, the panel has a ten-year product warranty and a 30-year performance warranty (i.e. after 30 years, the panel’s power output will be no less than 83% of its original output).
SunPower’s X22-370 DC
This is the company’s most efficient residential panel, with 22.7% efficiency and up to 370 watts of power. It’s composed of monocrystalline cells, and comes with a superb 25-year combined power, product and service warranty. SunPower does have a solar panel with 25% efficiency, but it’s small and built for seafaring (e.g. on boats).
LG’s NeON® R ACe
The NeON® R ACe launched in September 2019, and will look sleek, black and stylish on your roof. It offers 22% efficiency and a maximum power of 380 watts. Made of monocrystalline cells, the NeON® R ACe has a 25-year combined product and performance warranty.
JA Solar’s 78-cell MBB Half-cell Module
With a 21.7% efficiency rating, JA Solar’s 78-cell MBB Half-cell module offers higher power output than many other panels, better temperature-dependent performance, reduced shading effect on energy generation, and lower risk of hot spot.
Panasonic’s HIT® N340
This panel offers an efficiency of 20.4% and a maximum power of 340 watts, coming with a water drainage system at its corners that helps with self-cleaning. The panel is made from amorphous thin-film silicon layers, not monocrystalline or polycrystalline cells, and has a 25-year combined product and performance warranty.
Yingli Solar’s PANDA Bifacial 60CL
This solar panel certainly comes with the cutest name, and is capable of 20.1% efficiency and 330 watts of power. Comprising monocrystalline cells, the PANDA panel has a ten-year product warranty and a 25-year performance warranty.
Sharp’s NQ-R Series 258W
Launched earlier this year, the NU-JD440 solar panel is a half-cut monocrystalline product that offers a 19.9% efficiency rate and 440 watts of power output. You’ll also be able to rid your mind of any worries about damage, since it comes with a 25 year linear power output warranty and 15 years product warranty.
Who makes the most efficient solar panels?
Every solar panel manufacturer is constantly tweaking their technology, trying to get the most out of the sun to fuel this renewable energy source. There’s nothing like a bit of healthy competition, and it just means better solar panels for homeowners.
Here are the highest, lowest, and average efficiencies for the solar industry’s top manufacturers:
Solar panel manufacturer
To find out more about the leading solar companies and their range of solar panels, visit our guide to the best solar panels.
How do you calculate solar module efficiency?
To calculate a solar panel’s efficiency, scientists test it in a lab. People in white coats measure how much sunlight a panel can convert into electricity, before releasing it onto the market.
The Standard Test Conditions (STC) for calculating solar panel efficiency aim to simulate a clear 25°C summer’s day, which means an irradiance of 1000 W/m2.
Obviously, not every day is a 25°C summer’s day (especially not in the UK), so most ‘maximum efficiencies’ are rarely achieved in the real world.
Fortunately, some solar panels are starting to come with a Performance Test Conditions (PTC) rating, which is a more accurate measure of the efficiency you can expect from a panel on your roof.
Better still is the ‘system PTC rating’, which takes into account the efficiency of a solar panel as well as that of the inverter (the device that converts the solar panel’s electrical power into usable electricity for your home).
Even if your solar panel has a high efficiency, it won’t be able to spread its wings if there’s a low-efficiency inverter dragging it down.
Which type of solar panel is the most efficient?
The vast majority of residential solar panels are made from silicon cells, but there are three different types of cell: monocrystalline, polycrystalline, and thin-film. Each cell comes with a different level of efficiency:
Monocrystalline is the crème de la crème of solar panel materials, constructed from just one single piece of silicon. It’s a solid block with no imperfections, making it super efficient at converting sunlight into electricity. Monocrystalline is the most expensive option, but you certainly get what you pay for.
Polycrystalline is a small step down, created by using a poured mixture of multiple silicon crystals. If monocrystalline is like single malt whisky, polycrystalline is like blended whisky. In contrast to monocrystalline’s “solid block” state, polycrystalline comes with imperfections and spaces, and has a distinctly bluish, flaky appearance. You’ll get larger solar panels with lower efficiency, but you’ll pay less for them.
Thin-film (or amorphous) solar cells are the least efficient of the three, involving just a thin layer of silicon on top of the electrical components (as opposed to a whole block). Although thin-film rarely achieves efficiency levels over 15%, they are popular for their low weight and high flexibility. Thin-film panels can also be transparent.
If you’d like to learn more, head to our page on different types of solar panels.
There is an additional type of solar panel showing promise for the future: Perovskite solar cells. These are tandem solar cells which are created when a thin perovskite cell is placed on top of a standard silicon cell.
The perovskite cell is made of synthetic material that’s been modelled on the special crystal structure of a mineral called perovskite. This structure absorbs sunlight in a different, more effective way than silicon cells.
Although these aren't yet available for residential homes, they provide a glimpse of what might be in store for the future. In 2018, Oxford PV broke the world record by demonstrating its perovskite-silicon tandem cells could work at 28% efficiency – around one-third more than current standard PV panels.
What is the maximum efficiency of solar panels?
The only “maximum” in solar panel efficiency is 100%, and we’re nowhere near that level.
Back in 2014, a bunch of clever scientists reached a new world record with a remarkable 46%, but residential solar panels aren’t quite as good.
The highest efficiency you’ll find on the market at the moment is around the 25% mark, and the majority of ‘high-efficiency’ solar panels fall somewhere between 18% and 23%.
Do solar panels lose efficiency over time?
The unstoppable march of time leaves its mark on everything, solar panels included.
The efficiency of a solar panel tends to fall by about 0.5% each year (this is called the degradation rate), but most manufacturers provide a 25-year performance (or ‘linear output’) warranty.
This typically guarantees that the panel’s output won’t drop below about 85% of its original efficiency within the first 25 years, although this figure can vary.
Is it worth buying high-efficiency solar modules?
If you’re keen for a piece of the solar energy scene, but have limited space, high-efficiency solar panels are the answer. The models are often compact and small, allowing you to power your property without requiring a vast roof.
How to maximise efficiency
As we’ve already mentioned, your solar panel will rarely perform at maximum efficiency because of the influence of other factors – some of which you have control over, and some of which you don’t. Here are the four key factors:
1. The direction and angle of your panels. It would be great if you could make your solar panels follow the sun throughout the day (a bit like a sunflower), but unfortunately most are static.
Ideally, you should have your panels facing southwards (although east or west is still sufficient), and positioned at an angle between 10-60 degrees. If your roof is flat or bizarrely steep, you can use racks to ensure your solar panels are at an optimum angle.
2. The amount of shade on your roof. Huge trees are a wonderful thing to have growing by your house, until they start obstructing your new solar panels.
It’s a common misconception that solar panels need sunlight to function (daylight is enough), but it certainly helps. We’re not saying you should kill the trees, but pruning them back a bit will make a big difference.
3. The temperature. Once the weather gets too hot (over 25°C), solar panels become less efficient – not that this is a significant problem in the UK.
Surprisingly, solar panels actually perform better in colder temperatures (like most electrical equipment), so a clear, sunny day in winter is ideal for your home’s solar energy.
4. The amount of debris on your solar panels. As dust and dirt gradually build up on your solar panels, their efficiency will decrease. Rain will do some of the cleaning for you, but you’ll have to do the rest yourself (or hire the services of professional solar panel cleaners).
If your home is regularly prey to belligerent pigeons, you might want to get your house some sort of roof scarecrow.
Finding an installer
This is where we come in – the Eco Experts can help you find local, professional solar panel installers with the best prices. To start collecting quotes for your home’s new solar energy system, simply fill in this quick form, and our suppliers will get back to you shortly with quotes to compare.