SunPower X-Series Panels Set New Efficiency Record Of 24.1%

sunpower panel efficiency

Sunpower X series panels have breached 24% efficiency.

I have previously mentioned SunPower makes excellent solar panels. This definitely includes their uncanny X-Series, which are a high efficiency, high reliability, line of monocrystalline panels. In January they broke the record for most efficient solar panel with a figure of 22.8%. And now, less than six months later, they have increased that by an impressive 1.3 percentage points to 24.1%.

I can only marvel at the improvements in PV efficiency that have occurred so far in 2016. Just six months ago I would have said the chance of any panel exceeding 24% efficiency this year would have been a long shot, but lately improving efficiency has been smashing records like an unstoppable juggernaut.

The Efficiency Figure Does Not Include The Frame

But before I get too fulsome in my praise, I should point out the efficiency figure is not quite as good as it sounds. This is because it only takes into account the area of the panel’s glass and not the frame. Fortunately the fame takes up very little space so won’t lower its overall efficiency by much. It may only take up as little as 6% or so of the area and so lower its overall efficiency down to around 22.6%. It is a little disappointing the efficiency figure SunPower gave can’t be used as the overall efficiency of the panels per square meter and has to be adjusted downwards.

X-Series Panels

The X-Series is available in Australia as a 345 watt panel with an efficiency of 21.5%. It is an extremely high quality panel and carries the longest product warranty in the industry with a period of 25 years. The panels aren’t cheap, but they are definitely good.

Currently there is no word on when higher efficiency X-Series panel will become available in Australia, but I am certain SunPower will want to get increased performance panels onto the market as soon as possible.

However, because Australia is blessed with plenty of sunshine and large roofs, it is possible other countries that aren’t so fortunate might snap them up when they first start being produced, as they may place more value on getting the most power from a limited amount of space.

The Benefits Of Higher Efficiency Panels

Higher efficiency panels are great news for anyone with a limited amount of space to install them, as they will give you more bang per panel. Or rather, more kilowatt-hours, as solar panels never explode. And if you tell me you have made them explode, you are clearly doing something very wrong.

Making panels that are more efficient at turning sunlight energy into electricity creates a whole slew of beneficial knock on effects. More efficient panels create less waste heat which reduces operating temperatures and improves efficiency. A lower operating temperature means less extreme thermal expansion resulting in less deterioration in performance over time.

And higher efficiency means less material has to be used to produce and install panels, which lowers the environmental footprint of solar power even further.

Future Developments

SunPower is not content to rest on its laurels. And I can respect a company that doesn’t ruin a perfectly good set of laurels by sitting on them. While they face numerous challenges to further improving efficiency that can be a real beast to overcome, they are gnawing away at the problem with the tenacity of a wolverine.

The individual cells that made up their latest record breaking module apparently had efficiencies of over 25% and SunPower says new cell designs can take results in the lab over 26%, so we can expect to see solar panels that are more than 25% efficient in the future.  Or perhaps 23.5% once the frame is included.

About Ronald Brakels

Joining SolarQuotes in 2015, Ronald has a knack for reading those tediously long documents put out by solar manufacturers and translating their contents into something consumers might find interesting. Master of heavily researched deep-dive blog posts, his relentless consumer advocacy has ruffled more than a few manufacturer's feathers over the years. Read Ronald's full bio.


  1. Many thanks Ronald for keeping us abreast of the developments in solar cell/panel efficiencies … it is greatly appreciated!

    I have been meaning to ask, since your last expose’ on Sunpower, if the interconnection methodology employed between cells would essentially eliminate the need for DC optimisers in a central inverter configuration (i.e. to help reduce inefficiencies created from dirt, bird poo, leaves etc)?

    I would be interested on your take on this please mate.



    • Ronald Brakels says

      Peter, SunPower panels should reduce the benefit of using optimisers, but shouldn’t eliminate it. This is because while a SunPower panel should not have its performance drop as much from being partially shaded as a typical panel, if one panel does have its performance reduced it can still bring down the performance of other panels on a string. So optimisers should still help improve the overall output of a system. Whether or not they would help enough to be worthwhile would depend on how important the owner thinks it is to maximize the system’s output.

      • Ahhh … yes of course Ron. Thanks mate for helping me calibrate my thinking here. I am looking forward to Finn’s article about Tigo Optimisers, which he committed to writing about some time ago. No pressure Finn … but where is the article mate? 🙂 Cheers Peter

  2. Guys top site and thank you for all the info which help me design my own system.
    I have decided to use X21 345 sunpower panels with a solaredge 7300 to drive them. These panels are something else and my system is spit in 3 direction with a total of 7.5KW.
    My test and benchmark on similar products with different T1 panels have shown me clearly the diffrence on why the panels are an important choice.
    So far I am producing more power than any system up to 8 KWS I have compared in my area and especially during a bad day the system is producing 25 to 30% more than a fully north facing system with other panels total of 8KW
    However I am not focusing on the total power its producing but how its delivering the power during the day and that’s more impressive as my system can never run at 100% due to the positioning of the panels.

    The panels are rated 345W however I have seen production out of them at 385W which is amazing.
    money well spend in my view ..


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