Evaluation of module performance after extended accelerated ageing tests

In the current study, we present the evaluation of solar PV modules made with the Borealis encapsulant after various accelerated ageing tests, like damp heat, thermal cycling, humidity freeze test and PID test.

Lamination process

The typical lamination cycle time with Quentys™ BPO is described below.

Parameters Typical value
Temperature 145 - 160 °C
Pressure 800 mbar
Total cycle time 8 - 15 min
Being thermoplastic in nature, Quentys™ BPO provides high flexibility while fine tuning the detailed set up of the lamination process by module producers.
Extended damp heat (DH) test

The 60 cell modules, produced with Quentys™ BPO, were exposed to damp heat testing (85% relative humidity and 85°C) following IEC61215 for up to 4000 hours, at an interval every 1000 hours. The power output change with damp heat exposure time is shown in the following figure:
Extended thermal cycling test (TCT)

The modules produced with Quentys™ BPO, when tested for 600 cycles of TCT following the IEC61215 test conditions, show no significant change in power output. Other parameters, like current output, fill factor, etc. are also not affected significantly. The electroluminescence study shows no cell breakage after such a long test.
Extended humidity freeze (HF) test

Modules made with Quentys™ BPO encapsulant were tested under humidity freeze test conditions according to the IEC61215 test conditions i.e. UV preconditioning followed by 50 cycles of TCT and then the humidity freeze test. According to the IEC procedure, it is required to do only 10 HF cycles, while we tested up to 30 HF cycles. From the results shown below, it is apparent that modules made with Quentys™ BPO can easily survive such an extended ageing test without any significant change in the power output. The EL study of the modules afterwards also show no significant changes in cells and connectivity.
Conclusions

Quentys™ BPO is a new kind of polyolefin based thermoplastic encapsulant film offered by Borealis based on its proprietary polymer technology, it offers not only a fast lamination process cycle but also a very robust performance according to all the industry known accelerated ageing tests. It is obvious that this encapsulant film will contribute to improved economics and the long term stability of solar modules used in actual applications.

Evaluation of module performance after extended thermal and UV ageing

In the current study, we present the evaluation of solar PV modules made with the Borealis encapsulant after thermal and UV ageing.

Lamination process

The typical lamination cycle time with Quentys™ BPO is described below.

Parameters Typical value
Temperature 145 - 160 °C
Pressure 800 mbar
Total cycle time 8 - 15 min
Being thermoplastic in nature, Quentys™ BPO provides high flexibility while fine tuning the detailed set up of the lamination process by module producers.
UV ageing test

One cell mini modules made with UV transparent Quentys™ BPO and state of the art EVA encapsulant was tested up to 300 kwh/m², which is much higher than the dose of 15kwh/m² used in IEC61215. The degradation of the modules after UV ageing was investigated by electroluminescence (EL), performance measurements and peel testing. For each UV dose, three identical modules were tested.

Short circuit current and power output after UV ageing

Even after 300 kWh/m² UV dose, there was not more than a 2.0% decrease in power output and short circuit current. These results show the high stability of the Quentys™ encapsulant against UV degradation.

Adhesion results after UV ageing

The mechanical characterisation of the tested material and the characterisation of the adhesion of the encapsulant to the glass and to the back sheet can be investigated by peel testing at a 90° angle according to the standard DIN EN 28510-1.

Electroluminescence study after UV ageing
Thermal ageing

Thermal ageing of the glass-encapsulant-backsheet laminates was carried out in a standard heat ageing oven at 125 °C for 6 weeks. The changes in colour after 6 weeks are shown below, where the Borealis encapsulant shows much less discoloration.
Conclusion

Borealis’ UV transparent Quentys™ shows a robust stability against UV and thermal ageing. In spite of having no UV absorber in Borealis’ UV transparent Quentys™ encapsulant, no risk on module performances in real application is anticipated.

Evaluation of module performance after multiple combined stress test cycles

In the current study, we present the evaluation of solar PV modules made with Quentys™ BPO and reference EVA encapsulants after a combined stress test sequence developed by Fraunhofer ISE, Freiburg, Germany.

Lamination process

The typical lamination cycle time with Quentys™ BPO is described below.

Parameters Typical value
Temperature 145 - 160 °C
Pressure 800 mbar
Total cycle time 8 - 15 min
Being thermoplastic in nature, Quentys™ BPO provides high flexibility while fine tuning the detailed set up of the lamination process by module producers.
Combined stress test sequence

Test sequence 1:

One cell mini modules made with UV transparent Quentys™ BPO and two reference EVA encapsulants (one UV absorbing and the other UV transparent) were subjected to UV ageing under damp heat conditions for up to 2000 hours. After every 500th hour, modules were evaluated for performance, EL study and colour measurement.

Test sequence 2:

Full size modules (60 cells) were subjected to the following combined stress test sequence. 3 test cycles (x = 3) were conducted in total. The total UV dose during the initial and also each individual cycle was approximately 60-75 kWh/m².
Performance measurement after test sequence 1

In the combined UV DH test, even after 2000 hours of ageing modules, the Borealis Quentys™ encapsulant shows less than a 2% decrease in short circuit current and power output. The reference EVA encapsulant based modules show a drastic decrease in performance after 1500 hours of ageing. The EL picture shows that EVA based modules develop dark marks around bus bars which might be due to the corrosion of the silver grid fingers. Such degradation is not observed in the case of the Quentys™ BPO encapsulant.
Evaluations after test sequence 2

Performance measurement:

Wet insulation test results:
Conclusion

The combined stress test, as proposed by Fraunhofer, is extremely harsh, accelerated testing to check the long term stability of the solar module. The Borealis Quentys™ encapsulant shows robust stability in this test compared to the state of the art EVA reference encapsulant. These test results clearly demonstrate that in actual field applications, the Borealis Quentys™ encapsulant will significantly contribute to reduce the degradation of module performance with time.

Quentys™BPO8828F

Quentys™BPO8828F is a novel Polyolefin based encapsulant film especially designed for glass/flexible backsheets with E-layer and double glass modules.

Availability

Quentys™ BPO8828UV: back encapsulant with UV absorber available for testing in December 2016.
Quentys™ BPO8828WH: high reflective white back encapsulant available for testing in 2017**

* Only use with E-layer based backsheets
** Under development

Datasheet

Download Quentys™ BPO8828F datasheet

Processing guidelines

Processing of Quentys™BPO8828F on laminators with oil based heating system
Compared to laminators with electrical heating, the heat transfer of oil based laminators is somewhat slower

Recommended to modify the lamination cycle accordingly.

For lamination cycle optimisation use the following methodology:
1. Determine optimal evacuation time
2. Use optimal evacuation time from step 1 & determine optimal holding time

Lamination guideline for glass/flexible backsheet modules
Step 1: evacuation time

Step 1: determine optimal evacuation time

Start with cycle 1 - use 150 sec evacuation
Check with EL pictures for cell breaks
If there are no breaks: 150 sec evacuation is OK
In case of cell breaks, use cycle 2: increase evacuation by 30 sec
If there still are cell breaks, use cycle 3 increase again by 30 sec

Lamination temperature 145°C	Cycle 1	Cycle 2	Cycle 3
Evacuation	150 sec	180 sec	210 sec
Pressure build up to 200 mbar or -80 kPA	30 sec	30 sec	30 sec
Pressure build up to 800 mbar or -20 kPA	30 sec	30 sec	30 sec
Holding time @ 800 mbar or -20 kPA	210 sec	210 sec	210 sec
Total cycle time	420 sec	420 sec	420 sec

Lamination guideline for glass/flexible backsheet modules
Step 2: holding time

Step 2 : determine the holding time

Use the evacuation time* of step 1 and start with a holding time of 210 sec
Measure the adhesion strength against glass, wait minimum 2 hours for measuring
If the adhesion strength > 80 N/cm then a holding time of 210 sec is OK
In case of low adhesion strength or high variation, increase holding time by 60 sec
If adhesion strength is still < 80 N/cm: increase holding time again by 60 sec

Lamination temperature 145°C	Cycle 1	Cycle 2	Cycle 3
Evacuation	150 sec*	150 sec*	150 sec*
Pressure build up to 200 mbar or -80 kPA	30 sec	30 sec	30 sec
Pressure build up to 800 mbar or -20 kPA	30 sec	30 sec	30 sec
Holding time @ 800 mbar or -20 kPA	210 sec	270 sec	330 sec
Total cycle time	420 sec	480 sec	540 sec

Internal investigation: influence of short versus long holding time on adhesion strength & variation
Double glass production issues resulting into waste during lamination process
For crosslinking encapsulants – higher risk for failures during lamination
1. Material flow out: risk for contamination of laminator > cleaning required
2. “Swimming” of glass: risk for cell matrix movement or bad positioning of glass
3. Bubble formation: evacuation of reaction products (~POX) is difficult due to weight of glass
4. Edge pinching: results into bubbles at the module edge – wasting of PV module
Quentys™BPO8828F offers easy module production

Waste is lower compared to crosslinking encapsulant systems

Quentys™BPO8828F features shorter cycle time & can be relaminated
Other advantages of Quentys™ BPO8828F in double glass modules
Moisture sensitivity compared to EVA & PVB is significantly lower
1. Low WVTR
2. “Swimming” of glass: risk for cell matrix movement or bad positioning of glass
3. Beneficial for modules without edge seal
PO: preferred material for frameless double glass modules
Very high adhesion strength
1. Ball impact test: challenging for EVA & POE based modules
2. Ball impact test is also more critical if thinner glass is used (~2–2,5mm)
In both cases high adhesion strength benefits towards the impact test, glass is shattered into smaller pieces

Lamination guideline for 2mm double glass modules

Lamination temperature	145°C
Evacuation	390 sec
Pressure build up to 200 mbar or -80 kPA	30 sec
Pressure build up to 800 mbar or -20 kPA	120 sec
Holding time @ 800 mbar or -20 kPA	360 sec
Total cycle time	900 sec

Lamination guideline for 3,2mm double glass modules

Lamination temperature	155°C
Evacuation	390 sec
Pressure build up to 200 mbar or -80 kPA	30 sec
Pressure build up to 800 mbar or -20 kPA	120 sec
Holding time @ 800 mbar or -20 kPA	360 sec
Total cycle time	900 sec

For laminating at 145°C: increase evacuation time by 1–2 minutes (to be tested)

Photo: Borealis Quentys™ grades are used to encapsulate and protect the solar cells mounted on the racing car built by the Agoria Solar Team.
Photo: © Agoria Solar Team

Solar encapsulant film based on grades from Borealis’ pioneering Quentys™ portfolio will protect the roof-mounted solar panels on the team’s racing car and maximize their potential. Borealis and Borouge’s support reflects their aim to empower solar energy on an international scale, by making it more reliable, efficient and affordable.

Racing in the outback

as the ultimate test

Empowering Solar with Quentys

Empowering the racing team is a new way for Borealis and Borouge to cooperate with innovative partners along the value chain, to develop and implement novel and superior solar products based on Quentys. Like other teams participating in this race, the Agoria Solar Team is made up of university students – in this instance from the KU Leuven university in Belgium – who design, build, and race their own solar vehicles.

In June 2018, two new encapsulant film types were commercially launched. These are based on Borealis Quentys polyolefin (PO) grades and further improve long-term PV module performance, reliability and cost efficiency. The Agoria Solar Team is now using both films to encapsulate and protect the car's solar cells. This will increase their power output, making the car faster and expanding its range in a most efficient way.

”I would be hard pressed to find a better demonstration of the power of solar than this race," says Rudi Peters, Borealis Global Value Chain Manager Solar. "Our Quentys encapsulant films will enable this young and ambitious team to power their racing car better and more efficiently. What is more, by sponsoring the next generation, Borealis is fostering innovation which will ultimately benefit the entire solar industry."

"Our testing of the Quentys front and back encapsulant confirmed its stability and ease of use, and its great optical properties mean that losses will be kept to a minimum," explains Nelis Geurts, the Agoria Solar Team member responsible for producing the car's module. "It will enable us to exploit every last bit of energy from the sun. We are confident that this partnership with Borealis will help us to be the first solar car to cross the finish line in Australia."

Launch of 2019

BluePoint race car

Using solar encapsulant film based on Quentys™ grades

The solar race car called “BluePoint” is using solar encapsulant film based on grades from Borealis' pioneering Quentys™ portfolio and was officially presented by the engineering students of the University of Leuven, Belgium on July 3, 2019. Three layers of solar cells wrapped in a protective paper-thin encapsulant film based on Borealis Quentys material will ensure maximum light absorption capacity. The solar panel is 2.6 square metres in size and 1.5 millimetres thick. The total costs of the car amount to over EUR 1 million and it is expected to achieve a maximum speed of 130 kilometres per hour.

Borealis is proud to be a partner of this innovative and ambitious project and is looking forward to follow the race team during the upcoming Bridgestone World Solar Challenge in Australia. The race will take place from 13 – 20 October 2019, starting in Darwin and ending 3,000 kilometres later in Adelaide. Borealis is confident that the team will reach its ultimate goal of crossing the finish line 1^st and wishes the Agoria Solar Team the best of luck.

Nelis Geurts, Electrical Engineer, Agoria Solar Team and Rudi Peters, Value Chain Manager Solar, Borealis
© Agoria Solar Team

Key facts

about the project

The Bridgestone World Solar Challenge (BWSC) takes place every two years. Here are some key facts about the Punch Two, which the Agoria Solar Team entered in BWSC 2017:

Punch Two's solar panel is equivalent to 1,000 watts or 25 ordinary 40W lights bulbs. The panel has an efficiency of 34%, making it 2.3 time more efficient than standard roof solar panels.
Punch Two won the Innovation Award at BWSC 2017 with its four wheel steering system. The driver is able to rotate the wheels and use the body of the car as a sail to ride the wind.
Punch Two weights just 140kg without the driver, equal to the weight of two adult kangaroos.
During the race, the car's battery can only be charged with solar energy from 07:00 to 18:00 and cannot use power from the electrical grid.
The car's endurance and reliability are very important, with a distance of 3,021 kilometres to cover over four and a half days, in temperatures that can rise up to 50^oC.

The team's aims

The team's aims to act as a catalyst for making commercial solar-powered electric vehicles available to the masses. It looks to push the boundaries of technology, by developing a car that will shape the future of durable mobility.

In building the car, the team want to:

Promote renewable energy
Generate interest in science and technology among young people
Promote advanced technologies
Facilitate and encourage entrepreneurship

These aims align with Borealis' own sustainability goals.

Borealis Borouge

Empowering

solar

Watch trailer

Solid ownership

and global reach

Solid ownership and global reach

We are a bankable company and have proven our reliability as a partner for the energy sector worldwide.

Borealis is a leader in the global polyolefin industry, backed by a strong and strategic ownership foundation shared with our joint venture Borouge.

We have a strong track record of constant growth that enables us to advance innovative ideas all over the world in various industries, including automotive, piping, healthcare, packaging, and wire and cable.

Our experience partnering with the energy industry includes 45 years of innovating demanding cable applications for which reliability and performance are a must. Today, we continue to drive our international expansion, establishing local presences to keep pace with the growth of the global solar market.

Throughout the value chain we strive for effective cooperation with our business partners to ensure our products meet their expectations. And by actively collaborating with international standardisation bodies, we take responsibility for securing the long-term performance of solar modules and protecting the environment.

New Polyolefin based encapsulant from Borealis

Borealis has introduced new polyolefin based encapsulant film grades (Quentys™ BPO) for solar photovoltaic modules. The new encapsulant is thermoplastic in nature and is free of organic peroxide. The lamination cycle time with this encapsulant can be reduced significantly compared to conventional EVA and other polyolefin based encapsulants.

Making solar energy

more affordable

Our encapsulants increase the reliability, performance and cost efficiency of solar power modules.

Third-party comparative testing^* confirms that Borealis encapsulants extend the lifetime of solar modules and increase their power output over time because they offer industry-leading resistance against:

Moisture induced corrosion
UV induced degradation
Electrochemical failures

* Tüv Rheinland, Fraunhofer & imec

Borealis Quentys™ grades boost a solar racing team

Borealis and Borouge, leading providers of innovative, value-creating plastics solutions, are supporting a Belgium-based racing team taking part in the 2019 Bridgestone World Solar Challenge in Australia. Known as the world championship for solar cars, the 3,000-km race across the outback is the ultimate test for a solar-powered vehicle.

Discover more

Evaluation of module performance after extended accelerated ageing tests

Discover more

Evaluation of module performance after extended thermal and UV ageing

In the current study, we present the evaluation of solar PV modules made with the Borealis encapsulant after thermal and UV ageing.

Discover more

Evaluation of module performance after multiple combined stress test cycles

Discover more

Value creation

through innovation

Value creation through innovation

Through step change innovations, we can supply the solar industry with superior materials for the production of photovoltaic modules.

Lamination

Borealis encapsulants offer improved reliability and processing in the lamination process.

Fewer failures reduces production losses
Compatible with different types of laminators

Cost reduction

In addition to processing benefits, our products also provide secondary advantages.

Significant electricity cost savings
Reduced maintenance

Higher output

The outstanding processability of our encapsulants ensures optimised productivity.

Significant reduction in lamination cycle time
Capacity increase without investment

Outstanding performance

Our materials are suitable for key market segments, enabling distinctive solar module capabilities.

Standard & double glass modules
Resistance to harsh climate conditions
Suitable for modules with higher system voltage

New Polypropylene based advanced compounds for production of backsheets

Polypropylene (PP) based advanced compounds designed specially for production of backsheet layers, providing clear advantages over PET backsheets. Borealis makes these PP compounds available to the market by partnering with selected backsheet producers.

Quentys SF700CL (core layer)
Quentys SF900WL (white outer layer)
Quentys SF900BK (black outer layer)

Borealis offers PP compounds that pass all test in the PV industry.

Tensile Modulus
Tensile Strength
Elongation at Break
Distance Through Insulation
Shrinkage
Thermal expansion
Thermal Cycle Test
Damp Heat Test
Relative Temperature Index
Hydrolytic Stability
UV resistance

Mechanical properties

Long term stability

Optical Properties

Electrical Properties

Processing behavior

Film appearance

Adhesion

Reflectiveness
Adhesion between layers
Adhesion to junction box
Water vapor transmission rate
Acetic acid permeability
Heat conductivity
Electrical Insulation

Standard PP grades will not pass all these tests for production of backsheet layers.

Coextruded PP based backsheets offer unmatched benefits for the backsheet and the module producer.

Backsheet producer

Reduced processing complexity

Coextrusion: a one-step production process
Fast and cost efficient process

Module producer

Improved module reliability

Extended module lifetime

No adhesives: reduced risk for delamination
Excellent hydrolitic stability
Low WVTR
High acetic acid permeability

The key strength of PP in comparison with PET and PA is the hydrolytic stability

Test	Conditions	Outcome
Damp Heat test	85°C, 85 % r.h. 10.000h	No delamination
HAST test	121°C, 100 % r.h. 250h	No delamination

The combination of humidity & UV is harsh for PET, therefore it needs protection by fluorinated outer layers.

The Borealis PP grades do not need this extra protection. It allows backsheet produces to replace the core PET layer by a core PP layer in laminated and coated backsheets and/ or using a 3 layer co-extrusion process with Borealis PP compounds to reduce the environmental footprint of the backsheets used in Solar PV.

Quentys™ SF700CL is a Polypropylene compound designed as a core layer backsheet offering clear advantages in backsheet production

Resin	Density	WVTR	Own co-extrusion possible
PET	1,38	<2g/M2.24h	NO
SF700CL	1,02	0,8g/M2.24h	YES

1. Density difference

Less kg SF700CL versus PET per SQM

2. WVTR

Reduce thickness of core layer with SF700CL versus PET

3. Co-Extrusion

Go in-house co-extrusion of SF700CL versus buying a PET layer film

QUENTYS^TM offers a step change in production cost efficiency for module makers while increasing power output, lifetime performance and reliability of PV modules.

Need more information?

Please contact us

Parameters	Typical value
Temperature	145 - 160 °C
Pressure	800 mbar
Total cycle time	8 - 15 min

Borealis

Very high adhesion strength

Borealis Borouge

Solid ownership

and global reach

Solid ownership and global reach

We are a bankable company and have proven our reliability as a partner for the energy sector worldwide.

New Polyolefin based encapsulant from Borealis

Making solar energy

more affordable

Our encapsulants increase the reliability, performance and cost efficiency of solar power modules.

Our encapsulants increase the reliability, performance and cost efficiency of solar power modules.

Borealis Quentys™ grades boost a solar racing team

Evaluation of module performance after extended accelerated ageing tests

Evaluation of module performance after extended thermal and UV ageing

Evaluation of module performance after multiple combined stress test cycles

Value creation

through innovation

Value creation through innovation

Through step change innovations, we can supply the solar industry with superior materials for the production of photovoltaic modules.

New Polypropylene based advanced compounds for production of backsheets

Borealis offers PP compounds that pass all test in the PV industry.

Coextruded PP based backsheets offer unmatched benefits for the backsheet and the module producer.

Backsheet producer

Module producer

Need more information?