Research
Photovoltaics (PV) is a widely known technology enabling the transition to a sustainable energy system. To ensure efficiency and reliability, EnergyVille investigates new materials and concepts for PV cell and module technology with a focus on PV power plants as well as the integration in BIPV, VIPV, and IIPV.
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Activities
Photovoltaics (PV) is a widely known technology enabling the transition to a sustainable energy system. To ensure efficiency and reliability, EnergyVille investigates new materials and concepts for PV cell and module technology. Next to deploying PV in PV power plants, the integration of PV in buildings, vehicles or other infrastructure is crucial for the integration of PV in an urban context and is hence at the core of EnergyVille’s PV research. As integrated applications require longevity and reliability, EnergyVille also studies PV module ageing and potential failure modes and develops solutions to increase PV module reliability. Our research on PV module level convertors combines the power generation with loads, storage and the grid in an adaptive fashion. Last but not least, we conduct research in energy yield metrology, and develop models for improved energy yield prediction and forecasting.
New silicon PV and thin film PV material and device developments
While the average user might only be acquainted with standard Silicon-based solar cell technology, the field of photovoltaics is in continuous evolution. Cells based on new thin-film absorber materials, like perovskites or CIGS, are approaching conversion efficiencies of Si cells at potentially lower cost and with more flexible sizing.
Understanding the material and device properties of these new perovskite solar cells is crucial to develop the processes that enable the realisation of devices with highest performance. This is why EnergyVille demonstrates these new materials and device architectures not only on small lab-scale devices but also on large area (30x30cm²) modules, and even full integration in final applications like buildings, vehicles and infrastructure.
High efficiency PV cell and module technology
To harvest as much energy as possible, EnergyVille is looking into various ways to improve the efficiency of PV-cells and module technologies. Bifacial crystalline silicon PV modules have recently gained a lot of interest because they can accept light from both sides in this way increasing the energy yield of the modules. EnergyVille takes these highly efficient bifacial cells as a starting point and combines them with optimised cell metallisation techniques and multi-wire interconnection technologies. This has resulted in a record-setting efficiency of 23.2% using bifacial n-PERT solar cells..
Building further on these evolutions, we have developed the concept of woven interconnection sheets by weaving encapsulant ribbons and metal wires into one fabric. This concept saves on materials and eliminates multiple process steps while it can still be run on industry-standard laminators, which are all significant advantages. Hence, this interconnection technology is a valuable new building block for our work in building and vehicle integrated PV.
Tandem cells
By combining two (or more) different solar cells with carefully selected material properties on top of each other in so-called tandem configuration, we can convert a wider part of the light spectrum into electrical energy. In this way we surpass the physical limitations of single solar cells. E.g. by combining a perovskite top cell on a silicon bottom cells, EnergyVille aim at reaching +30% tandem energy conversion efficiency which is larger than the theoretical maximum of about 28% of silicon solar cells.
At EnergyVille we explore different material combinations, processes and contacting configurations (2-terminal, 4-terminal tandems) towards realising large area (e.g. M2 size and up to 30cm x 30cm), stable and reliable tandem devices.
Integration of PV in building façades, vehicles and infrastructure
Bringing the energy source closer to the place of consumption and its integration into the built environment helps facilitating the sustainable energy transition by providing distributed generation. Doing so, EnergyVille explores the integration of PV into building façades, vehicles and other applications. This requires a close collaboration between experts on PV, architecture, building physics, and electrical engineering. Application-defined requirements drive the EnergyVille research in module converters and electronics, PV materials, PV cell and module technology, reliability testing, and energy yield simulation. Through large-scale demonstration projects we validate these technology and simulation results in real-life conditions.
Aesthetics and bespoke dimensions are a must in building-integrated PV (BIPV). EnergyVille works on the integration of PV in prefabricated elements, e.g. for curtain wall façades, and the implementation into planning tools to facilitate the design and manufacturing. We research aesthetic and reliable interconnection technology that enables mass customisation. We envisage a module assembly tool which, based on the input of architectural software, automatically assembles custom-made modules. Our multi-wire cell interconnection technology can flexibly adapt to module dimensions and will facilitate the implementation of Industry 4.0 principles.
PV cell and module analysis and performance optimisation
Since PV modules are applied in a variety of ways, assessment of their performance beyond testing under standard laboratory conditions is required. This has been largely recognised by the industry preparing novel IEC standards. We are closely involved in this process, and it is based on these insights that we have selected our tools.
Focused on exploration of new materials and technologies, we ensure that both industrial and small research samples can be measured in all our characterisation tools. Our cell and material and reliability characterisation research is supported by vast variety of opto-electrical characterisation tools (e.g. spectral response, reflectivity mapping, spectroscopy, high-resolution electroluminescence imaging) and material analysis tools (e.g. optical and electron microscopy, cross-section preparation tool, adhesion tester). Combining this broad set of characterisation capabilities together with the insights of our specialists enable us to understand the root causes of PV module performance reduction or failure and devise routes for performance optimisation.
PV module reliability
In reducing the levelised cost of electricity, lowering the degradation rate and preventing premature failures of PV modules are as equally important as efficiency. ‘Design for reliability’ is the foundation of various research activities performed at EnergyVille in the field of PV module reliability.
EnergyVille conducts in-depth reliability testing of the next generation of PV module materials and technologies. While we are applying standard accelerated test methods, our work goes beyond, establishing new tests and supporting the development of new standards. We design targeted reliability studies to investigate the weak points of the materials or technologies. By combining opto-electrical characterisation with destructive material analysis, we are able to uncover the underlying failure modes.
PV power converters (including modelling, testing and reliability)
In particular in building-integrated photovoltaics (BIPV), not all PV modules may generate the same power, voltage or current, owing to partial shading, reflections, and differences in sizing or orientation. To maximise the energy production in these circumstances, EnergyVille works on the development of customary electronic solutions that can adapt to a specific application. Novel module and converter technologies that enable efficient energy harvesting in non-uniform and dynamically varying conditions need to be optimised jointly. Therefore, we conduct research on power converters, which is linked to the work on DC buses and micro-/nanogrids.
Both for standard and reconfigurable PV modules, module level and intra-module converters must be compact for integration and must match the stringent reliability requirements. This asks for reliability testing and understanding of potential failures beyond the current standard metrics and measurements. We aim to not only measure failure rate but also degradation rates of such novel converter designs. For this we use accelerated synthetic mission profiles.
PV energy yield simulation & forecasting
EnergyVille’s energy yield simulation model is a scenario-based software which accurately simulates the expected daily energy yield of solar cells and solar modules under varying meteorological and irradiation conditions using available historic weather data. The model combines optical, thermal and electrical parameters to provide detailed insight on thermal variations in the solar module. The model integrates the effect of these variations, resulting in a significantly better accuracy than commercially available software packages for energy yield estimation. The simulation model is ideally suited to determine accurately the energy yield performance of new types of PV technology (e.g. bifacial PV plants) and in special conditions (e.g. floating PV, agri-PV, in BIPV, on trackers, on non-flat terrain, ...).
Simulation of the highly variable PV power generation in combination with battery storage and load management, taking into account grid conditions, is conducted in order to optimise system configurations for a range of applications, in order to obtain high degrees of self-sufficiency and self-consumption of the generated energy. This links the work on PV generation to the topics of battery system development, energy management and grid integration.
Projects
Labs
Photovoltaic Module Lab
Photovoltaic Module Lab
The PV Module Lab infrastructure is designed for fabrication and characterisation of PV modules with equipment that is state-of-the-art and/or beyond. As such, it is well-suited to evaluate and process both standard and new materials in the PV module value chain: cells, interconnect structures, encapsulants, backsheets and glass. Additionally, the versatility of the equipment allows for standard flat commodity PV as well as early-stage development of new interconnection and encapsulation technologies in an exploratory phase, while the same tools simultaneously accommodate scaling up to full-size panels (1m x 1.6m).
Advantages
Additional to the availability of advanced tools , the infrastructure is operated by experienced engineers and researchers for the development of next-generation PV module and interconnection technologies. The team members have an extensive background in PV materials, concept definition and proof, industrial (best) practices for standard and BIPV fabrication, characterisation and reliability, as well as in-depth knowledge of detailed solar cell (optical, electrical and thermal) behaviour and how this behaviour is translated into modules and systems (both in theory and in a practical implementation). In this way, we can carry out new technology development and offer objective technology advice taking into account the overall perspective as well as the slightest details.
Applications
Processing designed for the fabrication of wafer-based crystalline-Si PV modules (or similarly applied in thin-film or an even
broader technology context):
- Laser processing
- Placement
- Dispensing
- Soldering
- Lamination
In-depth testing of the optoelectronic performance of devices (fabricated in our labs or elsewhere):
- Optical inspection
- Light IV
- Dynamic illumination
- Electroluminescence (EL)
- External quantum efficiency (EQE)
- Reflection (R)
- (Cross-section) scanning electron microscopy (SEM)
- SunsVoc (dependency of Voc on irradiance intensity)
- Thermal and spectral dependencies in behaviour
- Pull testing
Most of the equipment offers the opportunity of automation for its designated processing/testing, though the loading and unloading (and in some cases mechanical movement) are done manually to ensure the highest versatility in operation. Manual
preparations, rework and inspection can be done offline with state-of-the-art lab tables and tools. Dry room storage (0.4%RH) is available for moisture sensitive materials (e.g. encapsulants).
Customers
- PV cell and module manufacturers
- Material suppliers
- Equipment vendors
- PV system builders and operators
Technical notes
- Laser processing: high-resolution (scanhead) laser at 1070 nm and 15kW peak power, designed for cutting of metal
- wires and scribing of silicon cells
- Placement: high-resolution (±0.2 mm) gantry for automated layup (pick and placement) of silicon cells and (interconnect) foils with Bernouilli and vacuum gripping
- Dispensing
- High-resolution (±0.2 mm) dispensing with Auger valve for highly accurate (0.001g) volumes designed for solder pastes
- State-of-the-art dispensing based on pulsed dosing with compressed air designed for solder pastes and sealants
- Soldering with high-temperature accuracy and flexible programming of soldering profiles (up to 400°C)
- Beyond state-of-the art hot-air soldering with programmable air flow and temperature
- State-of-the-art industrial tabbing-stringing-based contact soldering
- Lamination with flexible programming of lamination profiles
- Beyond state-of-the-art high-accuracy flat-plate lamination allowing standard as well as inverse lamination cycles for highly accurate temperature-time-pressure profiles (up to 180°C). Lamination on lightly curved surfaces is possible.
- Small-area lamination for quick testing (up to 250°C) up to 60x 60 cm2
- Optical inspection
- Large-area (1x1.6m²) high-resolution (<0.2 mm) inspection with optional automation and stitching
- Small-area microscopy for optical (and SEM) inspection of detailed areas or cross-sections
- Light IV for accurate IV-sweeping of devices (up to 15A and 200V)
- Large-area illumination with LED-based spectrum- and intensity-tunable light source (18 colours 0.1-1.2 suns), temperature control (10-80°C) and optional 2-side illumination (for bifacial modules), designed for large PV modules (up to 1.6m²)
- Small-area tool designed for detailed inspection of cells and mini-modules
- Dynamic illumination with angular control and intensity-tunable and time-programmable LED tubes
- Electroluminescence (EL) for high-quality defect imaging
- High-resolution automated inspection in fixed setup
- Mobile setup for “fast and anywhere” testing
- External quantum efficiency (EQE) scanning for accurately determining spectral electrical sensitivity of devices in 300-1200 nm range
- Reflection (R) scanning for accurately determining spectral reflective sensitivity of devices in 300-1200 nm range
- Pull testing of materials with highly accurate control and monitoring of location, speed, load and strain designed for determination of mechanical yield stress, adhesion strength and shear forces through peeling (possible at different angles) relevant for PV modules (e.g. encapsulant adhesion, solder joint strength...)
Thin Film Photovoltaic Lab
Thin Film Photovoltaic Lab
Two types of photovoltaic materials are investigated: perovskites and CIGS (Cu-In-Ga-Se). In this lab the material properties are improved and the interfaces and the different layers in the thin film solar cell structure are studied and optimised. The size of solar cells can range from a few mm size (for the basic research) up to 35 cm x 35 cm thin film modules (to test applications). The thin film PV research is also embedded in the collaboration consortium Solliance*.
Advantages
CIGS RESEARCH:
There are two main R&D topics on CIGS studied:
- Passivation of CIGS absorber layers to achieve a thinner and simplified CIGS absorber material. The cost and reliability of CIGS solar cells can be improved substantially with this approach as has been shown already for silicon solar cells. The end goal is to realise high efficient CIGS solar cells with low cost and long reliability.
- New absorber materials are developed for future applications. For tandem cells, a high band gap version (above 1.6 eV) of CIGS with pure sulphur (Cu-In-Ga-S) or CGS (Cu-Ga-Se) is under development to be used as the cell on top of silicon bottom cell. Also, CIS (Cu-In-Se) is investigated as a potential for a bottom cell, when using e.g. a high band gap perovskite as the top cell. The CIS an also be used for applications whereby IR absorption is important. Besides CIGS compounds, also other sulphide and selenide compounds are possible to realise and study.
The lab has the capabilities to selenise and sulfurise precursor layers with elemental Se and S, as well as with H2Se and H2S gas. It allows to exploit the full potential of chemical reactions to create any sulphide or selenide compound and do in-depth investigations of the phase creation. The lab is equipped to finalise a complete solar cell device. All physical and optical-electrical analysis equipment for fast and advanced characterisation is present.
PEROVSKITE RESEARCH:
Over a relatively short development period, the initial efficiency of perovskite solar cells (PSCs) has rocketed from 3.8% in 2009 up to a certified record efficiency of 22.7% in 2017. So far these efficient PSCs are of small-scale (typically ≤1cm2). Despite this impressive initial performance, critical issues remain which hamper the industrial application of this material. Besides the instability, upscaling is another bottleneck for this PV technology. This upscaling is one of the key activities in the perovskite PV developments here.
The new assembly line allows to process full modules up to 35x35cm². A slot die coater can deposit solution-based materials while a vacuum thermal evaporation and sputtering system makes a combination of oxide and metallic coatings accessible for both passivation and electrode layers. Co-deposition of up to 4 materials is available, even to create quaternary photo-active layers like CIGS. In addition, a versatile 3-wavelength picosecond laser system is available for the creation of very narrow interconnections between adjacent cells in the modules. Dispenser and curing stations are available to complete the module packaging. All of these tools are integrated in or connected to controlled atmosphere gloveboxes.
The line allows versatility of carrier materials to be used, ranging from glass, plastic to metal sheets. This enables to create opaque or semi-transparent modules, either rigid or flexible. Variable interconnection schemes can be developed with the laser system to fabricate customised modules.
Applications
CIGS RESEARCH:
- CIGS solar modules
- Tandem solar cells
- Solar cells with sulphide or selenide absorber layers
PEROVSKITE RESEARCH:
- Customised solar modules
- opaque or semi-transparent modules, either rigid or flexible
- Tandem solar cells
- IoT up to BIPV
Technical notes
Deposition and processing tools available (from 5cm x 5cm up to 35cm x 35cm)
- Atmospheric anneal furnaces
- Vacuum selenisation furnace with H2Se and H2S
- S and Se elemental reactor furnace
- CdS chemical bath deposition
- Spin, blade and slot die coating
- Vacuum thermal co-evaporation
- Linear sputtering
- Mechanical scribing
- 3-wavelength picosecond laser patterning
- UV-curing press, robot and dispenser
Analysis equipment
- Class A IV set-up
- EQE
- Indoor IV set-up
- Atmosphere, temperature and light controlled climatic chambers
- Reflection/transmission/absorption
- SEM-EDS
- Carrier recombination life time meter (< 100ps)
- Photoluminescence
- 4-point probe
- Profilometer
- Laser scanning microscope
Photovoltaic Reliability Lab
Photovoltaic Reliability Lab
Reliability in photovoltaic (PV) systems is gaining importance because of various reasons; cost and applications. The Levelised Cost of Energy (LCOE) depends strongly on lifetime, while in Building Integrated PV (BIPV) for example, people expect lifetimes of 40 years and more.
The strength of the collaboration in EnergyVille is that all levels and elements of the PV system are covered in custom sample production, modelling and indoor custom-developed testing up to full size outdoor testing. Testing facilities cover many of the standards that are applied but are also developed custom in collaboration with industrial partners.
EnergyVille assists in validating reliability of industry’s new materials, technologies, topologies or solutions in the lab and in the field.
Advantages
- All current PV cell technologies can be integrated in test samples; crystalline silicon, thin film PV, perovskite solar cells, etc.
- PV modules can be fabricated form single cell laminates up to full size PV modules, including of the shelf and/or custom materials.
- Power Electronics can be stressed and monitored from small scale to medium scale applications
- Custom building elements can be designed and/or tested in both in- and outdoor setups on the roof of EnergyVille
- Mission profiles can be applied in modelling and in lab tests in order to determine degradation of specific components
Applications
- Photovoltaic cells
- Photovoltaic modules
- PV power electronics
- BIPV and Infrastructure Integrated PV (IIPV)
Customers
- Companies that develop new cells and cell interconnection technologies
- Producers of module materials (encapsulant, sealant, glass, coatings)
- Development of new production technologies in module manufacturing
- Construction companies looking to validate BIPV solutions
- PV power plant owners, operators and energy providers looking for expertise in reliability and extended reliability testing and fault diagnostics
Technical notes
Damp Heat
- Multiple chamber sizes
- Max. sample size: 1.1 x 1.7 m²
- Chamber load: 100 kg or max. 10 modules
- Damp heat testing at 5-90 ° C at 10-90 %RH
Thermal storage
- Multiple chamber sizes
- Sample size: max. 40 x 40 cm²
- Chamber load: 50 kg
- Temperature range: 50 - 250 °C
Thermal Cycling
- Multiple chamber sizes
- Max. Sample size: 1.1 x 1.7 m²
- Chamber load: 100 kg or max. 10 modules
- Thermal cycling: -60 - 150 °C
Potential Induced Degradation testing
- Custom setup for small to large modules and up to 4000 V
Mechanical stress testing
- Static and dynamic loads on max. 40 x 40 cm² mini modules
Light soaking chambers
- Multiple chamber sizes
- Max. sample size: 1.1 x 1.7 m²
- Chamber load: 100 kg or max. 10 modules
- Thermal cycling -50 -120° C and damp heat 5-90 ° C at 10-90 %RH without illumination
- Thermal cycling -20 -85° and damp heat 5-90 ° C at 10-85 %RH with illumination
- Light intensity and wavelength: 150 W/m2 at 250- 400 nm wavelength
Infrared imaging equipment for high speed failure detection:
- Detector 640 x 512 pixels
- High spatial resolution: <3 μm with x5 objective
- High NETD <20 mK
- High sample rate up to 5000 samples/s
Contact
prof. dr. Bart Vermang
EnergyVille
Thor Park 8320, 3600 Genk, Belgium