35th EU PVSEC, 24 - 28 September 2018
SQUARE - Brussels Meeting Centre, Brussels, Belgium

29 July 2017

Crystalline Silicon Research Highlights at the Upcoming 33rd EU PVSEC

While crystalline silicon continues to enjoy the lion’s share in PV manufacturing, it is impressive how much innovation and progress we are still seeing for this long-time incumbent solar cell technology. For the upcoming EU PVSEC in Amsterdam from 25-29 September, our Programme Committee has selected exciting research presentations for Topic 2 “Silicon Photovoltaics” (to be precise, 292 papers of which 84 are oral, 5 are plenary and 203 visual presentations).

A very good summary on hot topics in crystalline silicon R&D will be provided in the 5 presentations of the Silicon Photovoltaics Plenary Session (2 BP.1 on 26 Sept. at 10:30):

Kaneka will present a “Record-Breaking Efficiency Back-Contact Heterojunction Crystalline Si Solar Cell and Module”. So far, the Japanese company holds the world record crystalline silicon efficiency at 26.33% with its back-contact heterojunction (BCHJ) cell; for a module it has reached impressive 24.37%. Kaneka achieved its efficiency record using surface passivation technology employing amorphous silicon in combination with advanced metallization. Based on energy loss analysis, Kaneka emphasizes that its BCHJ technology has a potential to reach the 27% efficiency level.

The Energy Research Center of the Netherlands (ECN) will present “Pilot Line Results of n-Type IBC Cell Process in Mass Production Environment”. This cell production pilot line is based at Chinese integrated PV module manufacturer Yingli. The cells, based on an Interdigitated Back-Contact (IBC) design with a front floating emitter (FFE), have attained an efficiency of 21.1%. In pilot production, the cells are processed at a cost level of a p-PERC cells leading to efficiencies of 20.5% on 6-inch CZ substrates. The process was implemented in just 3 months, underscoring the compatibility of ECN’s process with a mass production environment. The presentation will also provide the path to improve efficiencies from 21.1% attained at ECN to 22% to be achieved at Yingli. Module interconnection is based on innovative conductive backsheets.

A key feature of a bifacial cell structure is having metallic contacts on both sides. That means, the metallization of such a bifacial cell is more complex as the parameters for the n-type and p-type surface are not the same. With an objective of simplifying metallization of bifacial cells in a cost effective way, Belgian research institute IMEC has developed a “Simultaneous Fabrication of n & p Contacts for Bi-Facial Cells by a Novel Co-Plating Process”. The process is based on electro-less and immersion plating. As only two thin metal layers are required, IMEC’s technology has a short cycle time during production and is based on a batch process, which is easily scalable and supports high throughputs. IMEC recommends multi-wire interconnection at module level for its approach.

PERC is the latest high-efficiency cell technology that has quickly gained large shares in mass production, however, this cell architecture is mainly implemented for monocrystalline substrates. The only bottleneck for adapting the technology to multicrystalline technology is the so called Light Induced Degradation (LID). While a few companies are producing multi PERC cell, the mechanism behind LID of multicrystalline cells has been a mystery to the solar community. The presentation “Understanding Light-Induced Degradation in Multicrystalline Silicon: Possible Complex Formation Mechanism” from Fraunhofer ISE will provide some explanations. The research work deduces possible candidates for underlying metallic impurity and proposes a model to explain LID for multicrystalline silicon cells.

Formation of high quality thin layers of multi-crystalline silicon on glass offers a way to reduce energy and material consumption – and thus also to decrease costs. Liquid phase crystallization using CW-diode lasers or electron beams has proven to form thin multicrystalline silicon layers on glass that exhibit wafer equivalent grain sizes and electronic quality. The Helmholz Zentrum Berlin (HZB), using an interdigitated back-contact system, has attained circuit voltages up to 642 mV and efficiencies up to 13.2 % for an a-Si:H(i/p+) / a-Si:H(n) hetero-junction device on a 13 µm thin absorber. In its talk “Understanding Light-Induced Degradation in Multicrystalline Silicon: Possible Complex Formation Mechanism”, HZB will discuss the results of further improvements, such as optimization of the interlayer absorber and the deposition process for the absorber.

Beyond this Plenary Session on Silicon Photovoltaics, EU PVSEC 2017 offers many more research results in this topic in the following sessions:

Silicon Photovoltaics Oral Sessions:

  • Characterization of Contacts and Doped Layers (25-09-2017, 13:30 – 15:00)
  • Characterization of Cells and Modules (25-09-2017, 15:15 – 16:45)
  • Industrial Production of Highly Efficient c-Si Solar Cells (25-09-2017, 17:00 – 18:30)
  • Silicon Crystallization (26-09-2017, 08:30 – 10:00)
  • LID and Defect Engineering (26-09-2017, 13:30 – 15:00)
  • New Wafering Technologies (26-09-2017, 15:15 – 16:45)
  • Novel Approaches for c-Si Solar Cells (26-09-2017, 17:00 – 18:30)
  • Production Technologies for Silicon Solar Cells (27-09-2017, 08:30 – 10:00)
  • c-Si Solar Cell Process Technology (27-09-2017, 13:30 – 15:00)
  • c-Si Homojunction Cells (27-09-2017, 15:15 – 16:45)
  • Thin Film and Foil-Based Silicon Solar Cells (27-09-2017, 17:00 – 18:30)
  • c-Si Heterojunction Solar Cells (28-09-2017, 13:30 – 15:00)
  • c-Si Solar Cells with Poly-Si Based pn-Junction (28-09-2017, 15:15 – 16:45)
  • Structures with Poly-Si based High / Low Junction (28-09-2017, 17:00 – 18:30)

Silicon Photovoltaics Poster Sessions:

  • Feedstock, Crystallisation, Wafering, Defect Engineering (25-09-2017, 13:30 – 15:00)
  • Homojunction Solar Cells (25-09-2017, 15:15 – 16:45)
  • Heterojunction Solar Cells (25-09-2017, 17:00 – 18:30)
  • Thin Film and Foil-Based Solar Cells / Characterization & Simulation Methods / Manufacturing & Production (27-09-2017, 13:30 – 15:00)