The AIKO Neostar 3 and the LONGi S10 are two of the most advanced home solar panels sold in the UK, and at 495W there is very little between them. AIKO is slightly more efficient per square metre (24.8% against 24.3%), while LONGi loses less output in heat and offers an identical 30-year performance guarantee. On most UK roofs, either panel gives you the same system size, so the better choice depends on your roof's heat, shading and layout rather than the brand.
| AIKO Neostar 3 | LONGi S10 | |
|---|---|---|
| Rated power | 495W | 495W |
| Dimensions | 1,762 x 1,134 mm | 1,800 x 1,134 mm |
| Module efficiency | 24.8% | 24.3% |
| Power per square metre | About 248W | About 243W |
| Temperature coefficient | -0.26% per °C | -0.24% per °C |
| Construction | Mono glass | Dual glass, bifacial |
| Weight | 21.1 kg | 23.5 kg |
| Performance warranty | 30 years, 88.85% at year 30 | 30 years, 88.85% at year 30 |
For the last couple of years, a homeowner who wanted the most efficient panel available had one real option, and it was AIKO. No other manufacturer could match its technology, so AIKO set the price and installers quoted it as the obvious premium choice.
That is no longer true. LONGi now matches AIKO on most of the datasheet, and beats it on some lines.
LONGi was founded in Xi'an, China, in 2000 and is one of the largest solar manufacturers in the world. It is listed on the Shanghai Stock Exchange. In 2012 it committed heavily to monocrystalline silicon and pushed its cost down far enough that the rest of the industry followed. The blue, speckled polycrystalline panels you still see on older UK roofs were largely replaced as a result.
AIKO was founded in 2009 and spent most of its history making solar cells, not panels. It sold those cells to other manufacturers, who put their own badge on the finished module. AIKO developed its all back contact cell in 2021 and opened its own module factory in Zhejiang province in 2023.
So LONGi has 25 years of manufacturing behind it. AIKO has around 15 years making cells and around five making complete panels. Both are large, publicly listed and rated Tier 1, which matters when you are relying on a 30-year warranty.
Each brand also makes more than one range. AIKO offers the Neostar for homes, Comet and Stellar for large commercial roofs, and Nebula, a lightweight glass-free panel for roofs that cannot carry a standard module. LONGi offers the S10 and X10 for homes and the Hi-MO 9 for large commercial roofs. If your roof suits an oversized panel or needs a lightweight one, those other ranges are worth asking about.
On a conventional panel, thin metal lines run across the front of each cell to collect the electricity. Those lines block light and generate nothing.
AIKO and LONGi both move every electrical contact to the back of the cell. AIKO calls its version ABC (all back contact). LONGi calls its version HIBC. Either way, the whole front face of the cell is free to generate.
Panel efficiency is measured by shining 1,000W of light per square metre onto the panel and measuring the output. Less wasted area on the front means more output from the same roof.
At 495W, the AIKO is 24.8% efficient, or about 248W per square metre. The LONGi is 38 mm longer, which brings it to 24.3%, or about 243W per square metre.
Because both panels have the same wattage and almost the same footprint, you will almost always fit the same number of either on a roof. Same panel count means the same total kWp.
The AIKO's smaller footprint only matters on a roof where the layout is a few centimetres short of fitting an extra row.
Every solar panel loses output as it heats up. The temperature coefficient tells you how much it loses for each degree the cells rise above 25°C, which is the standard test temperature. This is the temperature of the cells, not the air. On a UK roof in July, cells can reach 60 to 70°C.
The LONGi loses 0.24% per degree and the AIKO loses 0.26%. At a cell temperature of 70°C, the LONGi holds about 89.2% of its rated output (around 441W). The AIKO holds about 88.3% (around 437W).
That gap counts for most on hot days and on in-roof systems, where less air flows behind the panel to cool it. Across a full UK year, most generation happens in mild conditions, so the annual difference is a fraction of a percent.
When part of a conventional panel is shaded, a bypass diode switches in to protect it, and you lose the third of the panel that sits behind that diode.
Back contact cells handle shade differently. A shaded cell can effectively bypass itself through a controlled reverse breakdown, so the rest of the panel keeps producing.
In our own side-by-side demonstration, a standard TOPCon panel from another manufacturer stopped generating as soon as shade covered it. The LONGi back contact cells next to it kept running almost as if nothing had happened.
If your roof has chimneys, dormers or nearby trees, this is the most valuable feature either panel offers. A proper shade analysis will show whether it saves you from paying for optimisers or micro-inverters you may not need.
The AIKO is mono glass and weighs 21.1 kg. The LONGi has glass on both front and back and weighs 23.5 kg. On a roof with limited structural capacity, the extra 2.4 kg per panel adds up across a full array.
Dual glass construction also makes the LONGi bifacial, meaning it can generate from light reaching its underside. On a pitched roof, very little light gets underneath the panel, and our installation experience is that bifacial gain there is minimal. Flat roofs are different: light reflects off the roof surface and off neighbouring rows onto the back of each panel, so bifacial panels are worth considering there.
A product warranty covers manufacturing defects and material failures, such as faults in the frame, glass or electrical connections. A performance warranty guarantees that the panel will keep producing a set percentage of its original output as it ages.
Both panels guarantee no more than a 1% loss in year one. After that, the guarantee is no more than 0.35% per year, which leaves 90.6% of output at year 25 and 88.85% at year 30.
Product warranty terms can vary between variants of the same panel range. Check the exact model code and product warranty length on any quote you receive.
The two panels are priced similarly, and both cost a little more than mainstream panels. Panels are a modest share of a total system cost, though, so the premium is usually worth paying.
As an illustration, paying around £10 more per panel for roughly 10% more output pays back many times over across 25 to 30 years of generation.
The AIKO suits roofs where space is tight or where weight is a concern. The LONGi has the edge on hot roofs, in-roof systems and flat roofs with multiple rows. Both carry the same warranty, the same degradation curve and the same shade tolerance.
The bigger question is how much power you can get from your roof space. That depends on layout, shading and how you use electricity, and not on which badge is on the panel. Spirit Energy runs a full technical survey and shade analysis before recommending a panel, because the right panel is the one that gets the most from the roof you have.
Neither is clearly better. AIKO is about 0.5 percentage points more efficient, while LONGi handles heat slightly better and is bifacial. On most UK roofs, both give the same system size and almost identical annual generation.
Yes, better than conventional panels. A shaded back contact cell can bypass itself, so the rest of the panel keeps generating. A conventional panel typically loses a third of its output when one section is shaded.
Usually not by much, because very little light reaches the underside of a panel mounted close to a pitched roof. Bifacial panels earn their keep on flat roofs, where light reflects off the roof surface and neighbouring rows.