The fine art of cell connection with SmartWire Connection Technology (SWCT)

SmartWire Connection Technology is the most cost-effective method of connecting cells. It employs a foil-wire electrode instead of the conventional cell connectors (ribbons). This results in a significant improvement in efficiency while the negative effects of possible microcracks are reduced to a minimum.
In comparison to standard busbar technology, Meyer Burger’s SWCT delivers an increased performance yield of 3% for solar cells following encapsulation in the module. This is made possible by the dense contact matrix on the solar cell. The effective wire shading averages only 70% of the wire dia­meter through internal reflections in the SWCT design.
SmartWire Connection Technology

Figure 1: Main advantage is the use of busbarless cells bars assembled by wires to a front and back electrode (source: Meyer Burger)

In contrast to standard busbar technology where each finger routes the electrical currents to a busbar, SWCT connects all fingers together directly on the surface of the cell. The fingers are electrically connected in a close grid which even prevents the negative impact of micro cracks and cell breaks on the cell and results in an increased yield of around 1%. Eliminating busbars also reduces silver usage by up to 80%. SWCT is compatible to all silicon cell technologies and can also be used in the next generation of finger metalli­sation technology.

Using readily available materials, the straightforward HJT production process takes place at low temperatures and requires fewer production steps which is economically attractive as it results in significant energy cost savings for manufacturers.
 

Heterojunction technology (HJT) in a cell production line

Heterojunction cell technology is an appealing concept that combines the superior passivation characteristics of thin amorphous silicon (a-Si) layers with advantages of mono crystalline silicon (c-Si) wafers to realise cell efficiencies of over 22%. The simple structure of the HJT cells requires fewer processing steps compared to conventional cell designs. The excellent surface passivation of the a-Si layer results in a high cell efficiency potential. The superior temperature coefficient of TC = -0.2%/K for heterojunction cells results in higher energy yields during module operating conditions. Low temperature processing (< 250°C) saves energy during manufacturing and is compatible with the use of thin wafers.
Using readily available materials, the straightforward HJT production process takes place at low temperatures and requires fewer production steps which is economically attractive as it results in significant energy cost savings for manufacturers.
Heterojunction technology

Figure 2: Heterojunction cell technology: the thin intrinsic a-Si:H layers desposited between c-Si wafer and doped layers are the key to achieving maximum performance from the cell structure (source: Meyer Burger)
Metal Wrap Through (MWT) Technology

Unlike standard solar cells, Metal Wrap Through (MWT) solar cells are interconnected on the rear side. The front grid is contacted by metallized vias that lead the current onto the rear side. This reduces shading on the front side and ohmic losses due to cell interconnection. The MWT architecture thus achieves higher efficiencies while keeping the manufacturing costs low. The interconnection in the module can be realized by using either structured cell interconnectors or conductive back sheets.

In more than eight years of research and development in the field of MWT technologies, Fraunhofer ISE has cooperated with numerous industrial partners and achieved important milestones, such as:

  • Cell efficiency > 18 % for mc-Si and > 20 % for Cz-Si (p-type)
  • Cell-to-Module (CTM) performance loss < 1 % rel.
  • Production of MWT modules for a BIPV application
Metal Wrap Through
Figure 2: Metal Wrap Through (MWT) solar cells (source: Fraunhofer ISE)
Building Information Modeling (BIM)

BIM is an acronym that stands for “Building Information Modeling”. It is a new way of approaching the design and documentation of building projects.
BIM is a process by which digital representation of physical and functional characteristics of a facility are built, analyzed, documented, and assessed virtually, then revised iteratively until the optimal “model” is documented. The process then continues through construction and construction as-built documentation and again during the lifetime of the facility. As such, it serves as a shared knowledge resource for information about a facility forming a reliable basis for decisions during its lifecycle from inception onward. BIM is more than 3D modeling, although the 3D model is the geometric platform on which BIM operates. The ability to assign attributes and data to the objects in a 3D model is an important consideration in differentiating a 3D model from a building information model.

  • Building: the entire lifecycle of the building is considered (design/build/operations)
  • Information: all information about the building and its lifecycle is included
  • Modeling: defining and simulating the building, its delivery, and operation using integrated tools

BIM provides several major advantages over CAD (Computer Aided Design). BIM Models and manages not just graphics, but also information that allows the automatic generation of drawings and reports, design analysis, schedule simulation, facilities management, and more – ultimately enabling the building team to make better-informed decisions.

BIM supports a distributed team so that people, tools, and tasks can effectively share this information throughout the building lifecycle, thus eliminating data redundancy, data re-entry, data loss, miscommunication, and translation errors.
See the source (late accessed 01.13.2014)
 
This BIM environment requires a different business and thought process. The disciplines are brought together earlier to share information and work practices. Although this can create some disruption during initial adoption, the benefits (covered later), significantly outweigh this.

A basic premise of BIM is collaboration by different stakeholders at different phases of the life cycle of a facility to insert, extract, update or modify information in the BIM to support and reflect the roles of that stakeholder. BIM works on the basis of collaboration in construction. In this environment, all stakeholders in the construction process including Owner/Developer, Project Managers, Consultants, Contractors, Sub-contractors and Facilities Management, have access to the same design, cost and scheduling information at the same time.

Building Information Models (BIM) actually create facilities models within a computer. Because they are digital, computer-based models of building elements are infinitely more useful than hand or computer drafted drawings. Digital representation means that computers can be used to ‘build’ the capital facility project virtually, view and test it, revise it as necessary, and then output various reports and views for purchasing, fabrication, assembly, and operations. In many cases paper output may be avoided altogether when the finalized digital designs are directly sent to procurement systems and/or digital fabrication equipment.

Current facility information technologies and techniques function with little or no standard business process definitions. Relatively recent developments of standardized database schema have begun to standardize the packaging of information but standardized business process definitions are required in order for the functional pieces and process participants to work together efficiently.
See the source (late accessed 01.13.2014)
Building Information Modeling

Figure 3: Building Information Models (BIM) illustration (source: Buildipedia.com)