“The new dual glass Hi-MO 5 is interesting for all who value top-notch reliability and increased warranty.”


April 2023 marks the production start of the new bifacial dual-glass Hi-MO5 54c. We talked to Sebastian Pannier, Product Manager in Germany, to learn more about its unbeatable benefits.

Nadine: The Hi-MO 5 received an upgrade recently. Before we speak about the new 54c module, can you recap the Hi-MO 5 for us? What is it technically based on?

Sebastian: In the Hi-MO 5 we adopted the bifacial PERC technology. By their nature, PERC modules increase the efficiency of photovoltaic modules by reflecting part of the light that reaches the back of the cell, without having generated electricity, back into the cell. This is done by a special layer applied to the back of the module, also called backside passivation.

Additionally, the Hi-MO 5 is based on the new market standard M10 182-mm-monocrystalline wafer. According to industry sources, the market share for 182 modules had seen a rapid increase during 2022, moving from 27% in 2021 to a high of 70%. The module can achieve a power output of 540W and an efficiency of over 21%. For customers, the crackless, smart soldering technology has become a crucial feature.

Not to forget, the modules won the prestigious Intersolar award in 2021, and also earned the “Top Performer” awards from RETC (Renewable Energy Test Center) and other independent labs.

And I ‘am personally proud of the stringent testing methods we apply to our modules. For example, in the hailing test the module delivered excellent results. A TÜV SÜD report also verified that the Hi-MO 5 was successful in passing a 35mm hail impact test.

I think this all shows the trust the market has in the Hi-MO 5 and its reliability. This is also supported by the impressive global shipments which have exceeded 50GW with cumulative shipments now approaching 100 million panels. 

Nadine: Indeed! And now LONGi even adds something on top. The Hi-MO 5 has already been available as bifacial. So, what is new about the Hi-MO 5 54cell? What are the most important technical features?

Yes, there has been a bifacial version of the Hi-MO 5. But it’s still an important feature, if for the residential or industrial field, as it’s an easy way to increase the efficiency of the modules.

What’s truly new and a game changer for customers aiming for very reliable, durable, and resilient modules is the dual glass technology. Since the performance deterioration is much slower than the mono-facial panels, their lifespan is much higher. This is because the solar cells are completely enclosed in glass and don’t have an opaque or white backside made of metal-plastic or foil. As a result, the cells lie on the neutral axis of the connection and therefore do not experience mechanical stress when the module is bent, for example, under snow loads, hail, etc. The double glass module is less sensitive to moisture or chemical penetration than conventional modules.

Nadine: Why does the simple material “glass” has such a huge impact on the modules’ performance?

Sebastian: As per its nature, glass is incredibly stable in its performance and almost does not age. It is completely impermeable and therefore moisture resistant – it is the best choice for regions with high humidity. Moisture and oxygen cannot penetrate the modules; therefore, the aging process of the modules practically does not occur.

Nadine: Does that mean there are no PID and DH performance losses?

Sebastian: Yes, the Potential Induced Degradation (PID) and the Damp Heat (HD) are close to zero. The level of isolation is simply really good and reduces the cell connector corrosion to a minimum. Parasitic currents are avoided because no moisture will enter the modules. Each module is a closed entity.

There are also important mechanical advantages. Since the front and the back glass have the same thermal expansion, less stress and deformation are caused in hot or cold environments. The dual-glass furthermore provides better cell protection for mechanical damages, even at installation.

And finally, there are important security aspects. As glass is less flammable than foil, a larger proportion of the roof area can be used with glass-glass modules due to current fire protection regulations.

Nadine: What about the power output gain of the modules?

Sebastian: The power gain is increased compared to mono-facial modules. Dual glass solar modules can produce additional yields of 5 to 30 percent depending on the situation and installation on site, according to Fraunhofer Institute.

To what extent that is the case depends, for example, on the Albedo value (among other factors). It indicates what proportion of the incident radiation is reflected. For example, the albedo is about 10 percent for high sun over deep water, 10 to 30 percent for meadows and up to 75 to 95 percent for fresh snow. Therefore, the albedo of the environment has a significant influence on any additional yield.

It is therefore recommended, to use bifacial modules in locations with snow, because the rear side yield gain will not be affected, and the module operating heat can melt the snow on the front side.

But though rooftop installation is not an ideal installation type due to the downgrade of the bifacial power gain, there are clear arguments for bifacial dual glass: the power gain is >2% even with small gap installations on dark roofs and there is a much better module reliability that also impacts the warranty. 

Nadine: Warranty is, next to reliability and resilience, one of the most important factors for our customers. What are the warranties for the new dual glass bifacial Hi-MO 5 54c?

Yes, customers who value a durable module will like the increased warranty from 12 to 15 years for materials and processing and from 25 to 30 years for extra linear power output. We guarantee that the nominal power output of the module will remain at 85% after 30 years!

Nadine: What customer groups has the new module been designed for?

Sebastian: The module can be used for residential and C&I installations, in demanding and less demanding regions of the planet, as it is able to cope with a variety of extremes. Therefore, I would not assign a special customer group to the module. It is suitable for everyone who values a truly reliable, long-lasting, resilient solar panel and would like to benefit from an increased warranty of 30 years.

Nadine: I heard that at LONGi Europe, you are in general a big fan of the Hi-MO 5.

Sebastian: Yes, that is true. In the past and in my previous roles, I have been heavily involved in testing and long-term testing of bifacial and dual glass modules. They constantly achieved top marks. In terms of resistance and longevity, you simply cannot go wrong with this choice. For those who are fond of beautiful aesthetics – the module is also available in full black!

Thank you very much for this conversation and for taking the time, Sebastian!

The interview was conducted by Nadine Bütow, Head of Communications Europe of LONGi Solar DG.