The Most Efficient Solar Panels

Overview: Which Solar Panels Are The Most Efficient?

Solar panel efficiency isn’t to be confused with ideal annual output. Ideal annual output for a roof facing due south and at a 30° is 100%. In contrast, performance from some of the most efficient solar panels is just over 20%.

High efficiency solar panel brands include the likes of LONGi, Jinko, Panasonic, Suntech, Yingli, REA and Sunpower. 

All of these brands produce units offering in excess of 20% efficiency.

One of the most efficient solar panels available in the UK is the LONGi Hi-MO 6, operating up to 23.2% efficiency. This is coupled with an excellent warranty which covers: 

• Degradation rate of up to 1.5% in year 1
• Degradation rate of up to 0.4% in years 2-25

Expect installation costs to be £5,893 for a 5kW solar panel system, increasing to £8,388 with a small solar storage battery.

Installing highly efficient solar panels such as these could save you as much as £73.92 per year extra in comparison to low quality and inefficient panels. 

Get your fixed price using our clickable solar panel tool here. Our tool will suggest the most suitable setup for your property, incorporating the most efficient solar panels possible!

Our Guide To Finding The Most Efficient Solar Panels

Understanding Solar Panel Efficiency

The first thing to understand is the difference between ideal annual output, and actual efficiency. 

If we take a look at this table from the Energy Saving Trust, this shows the ideal annual output. This is based on both the tilt angle of your roof, and the orientation. 

Typically, a 30° pitch on your roof and facing due south is going to produce 100% ideal annual output: 

This is not to be confused with efficiency. The most efficient solar panels in the UK work at just over 20% efficiency, not up to 100%!

As an example of how much electricity an efficient solar panel system is likely to produce, we’ll use this, a 5.13kWh system: 

If this was working at 100% efficiency for 365 days a year, it would produce 44,938.8kWh per year of electricity. 

However, due to solar panels working at just over 20% efficiency (much lower for lower quality panels) and only a few daylight hours per day, you’re likely to produce somewhere in the region of 4,500kWh per year. 

This is typically enough to cover a medium-high consumption household’s electricity demand. 

Our clickable solar panel tool here will determine exactly what system your property needs. 

We use some of the most efficient solar panels on the market, able to work at well over 20% efficiency. 

The Most Efficient Solar Panels

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One of the most efficient solar panels we install is the LONGi Hi-MO 6. The Hi-MO 6 from LONGi offers a great balance of being cost effective, yet highly efficient. 

Efficiency

If we take a look at the Hi-MO 6 Guardian range, we'll see it operates at 23.2% efficiency (590w panel), well above the industry standard. 

Typical efficiency ratings are just over 20% for leading brands, but below 20% for no-name brands and cheap DIY setups. 

Degradation Rate & Warranty

But it’s not just efficiency on day 1 that you need to focus on. Solar panels degrade over time and as they do, their efficiency drops considerably. 

Check out this graphic produced from 8 Billion Trees. Typical panels will degrade at 2-3% in year 1, and 0.7% thereafter: 

What you need is a solar panel that’s backed by a product and performance warranty, and offers cover specifically for degradation rates. And, this is exactly what you’ll get from the LONGi Hi-MO 6 range. 

The basic manufacturer's warranty is 15-years. However, you’ll also get a 25-year performance warranty, which covers: 

• Max degradation rate of 1.5% in year 1
• Max degradation rate of 0.4% in years 2-25

This warranty from LONGi beats what’s offered from many other manufacturers producing some of the most efficient solar panels available in the UK.

Other Features

Other important features of the LONGi Hi-MO 6, include full back welding. This helps to reduce the chance of modules cracking. Essentially, any modules that are cracked in a panel are going to drop your solar panel system's efficiency considerably. 

And remember, temperature also affects solar panel’s efficiency. The Hi-MO 6 is designed to work in temperatures ranging from 40℃ - +85℃ with minimal drops in efficiency. If you plan to buy cheaper no-name panels, you’ll want to check they work within this range too.

You can read more about these units over at our LONGi solar panel review here. 

Or, you can use our solar panel configuration tool to build your system, using some of the most efficient solar panels available in the UK. 

Installation Costs For High Efficiency Solar Panels

A typical household in the UK is going to need a 5.16kW 12-panel system. The cost including installation for a setup using highly efficient solar panels from Dwellow starts at £5,893.

We’ll pick the most suitable panels for your property, so you should expect efficiency of these panels to be in the 22-23% range. 

Typically, we’d also suggest using a small 5.3kW battery as a bare minimum: 

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Whilst you will see the cost spike to £8,388, you’ll see some huge benefits. 

Savings on your electricity bill will increase from £632 to £730 annually. Any excess electricity your solar panels produce will be stored in your solar battery. 

Self-sufficiency for your property will jump from 24% to 54%. And let’s face it, the less you can rely on the grid (and not be at the mercy of rising electricity prices), the better. 

You can play around with our clickable solar panel tool here, and see how the different battery sizes affect price, electricity bill savings and self-sufficiency levels. 

Or for further reading, check out our guide to solar panel costs here. 

The Most Efficient Solar Panel Brands

There are 100s of solar panel brands available in the UK, not all of which offer a long warranty or are highly efficient.

Whether you’re planning to build a system on a DIY basis, or, have a MCS registered installer fit them for you, you’ll want to stick to leading manufacturers. 

The most efficient solar panel brands available in the UK include the likes of:

All of the brands we mention above offer a long manufacturer’s warranty, long performance warranty (which covers a specific degradation rate) and have panels in their range operating well above 20% efficiency. 

Using our solar panel configuration tool, you’ll be able to get a free online roof scan, to determine the best setup for your property. 

The Best Type of Solar Panels For Efficiency

You'll see a huge difference in price between panels. Dozens of factors affect this price including: 

However, one of the biggest differences in price will come from exactly how the panel is constructed.

The two most common types of solar panel are monocrystalline and polycrystalline. Polycrystalline solar panels are rarely manufactured anymore, due to the fact the highest level of efficiency manufacturers could achieve sits in the region of 15-18%. 

Monocrystalline is the superior option. Not only are monocrystalline units the most efficient type of solar panel, they'll also: 

• Last longer
• Work more effectively in extreme temperatures
• Have lower degradation rates over time
• Improve your overall return on investment!

Get quotes on monocrystalline solar panels with high efficiency ratings using our clickable solar panel system tool here. 

Degradation & Electricity Bill Savings

Efficiency on day 1 is important, but efficiency over time is even more important. As you can see below, typical solar panels might see a drop to 82% of their original efficiency over a 25-year period. 

LONGi spec’s show that their panels work at up to 23.2% efficiency on day 1. With them still achieving 88.90% of their original efficiency after 25 years you’d see them operating at 20.62% in year 25. This makes them one of the most efficient solar panels out of the box, but over a long period too. 

Compare that to lesser known brands where potential efficiency over the same period drops to 82%: Starting at 23.2%, they’d see efficiency drop to around 19%. 

The problem is, solar panels with a degradation rate this high most likely aren’t going to have a 23.2% efficiency rating in the first place. Starting at 20% on year 1, they’d end up at 16.4% by year 25. 

Assuming your solar panel system is producing 4,000kWh per year from day one, you’d see the following drops in efficiency: 

• Total of 3,556kWh/yr of electricity produced by the most efficient solar panels (such as LONGi) in year 25
• Total of 3,220kWh/yr of electricity produced for lesser known brands that follow the trend shown in the above chart

This might not seem a lot, but at an average price of 22p per kWh of electricity, you’d be saving approximately £73.92 per year extra with high quality panels. And with solar panels lasting 40 years and beyond, that’s £1000s you won’t save by buying lower quality panels. 

Ready to get your system installed? Use our clickable solar panel tool here, which will suggest the most suitable and most efficient solar panels specifically for your property. 

And for further reading, we’ve got a guide covering solar panel efficiency here. 

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