BIPV (Building integrated photovoltaic)Modules

Photovoltaics (PV) Technologies

There are two basic commercial PV module technologies available on the market today:

  1. Thick crystal products include solar cells made from crystalline silicon either as single or poly-crystalline wafers and deliver about 10-12 watts per ft² of PV array (under full sun).

  2. Thin-film products typically incorporate very thin layers of photovoltaicly active material placed on a glass superstrate or a metal substrate using vacuum-deposition manufacturing techniques similar to those employed in the coating of architectural glass. Presently, commercial thin-film materials deliver about 4-5 watts per ft² of PV array area (under full sun). Thin-film technologies hold out the promise of lower costs due to much lower requirements for active materials and energy in their production when compared to thick-crystal products.

A photovoltaic system is constructed by assembling a number of individual collectors called modules electrically and mechanically into an array.

Building Integrated Photovoltaics (BIPV) System

Building Integrated Photovoltaics (BIPV) is the integration of photovoltaics (PV) into the building envelope. The PV modules serve the dual function of building skin—replacing conventional building envelope materials—and power generator. By avoiding the cost of conventional materials, the incremental cost of photovoltaics is reduced and its life-cycle cost is improved. That is, BIPV systems often have lower overall costs than PV systems requiring separate, dedicated, mounting systems.

A complete BIPV system includes:

  1. the PV modules (which might be thin-film or crystalline, transparent, semi-transparent, or opaque);
  2. a charge controller, to regulate the power into and out of the battery storage bank (in stand-alone systems);
  3. a power storage system, generally comprised of the utility grid in utility-interactive systems or, a number of batteries in stand-alone systems;
  4. power conversion equipment including an inverter to convert the PV modules' DC output to AC compatible with the utility grid;
  5. backup power supplies such as diesel generators (optional-typically employed in stand-alone systems); and
  6. appropriate support and mounting hardware, wiring, and safety disconnects.
 
 

Design of a Building Integrated Photovoltaics (BIPV) System

BIPV systems should be approached to where energy conscious design techniques have been employed, and equipment and systems have been carefully selected and specified. They should be viewed in terms of life-cycle cost, and not just initial, first-cost because the overall cost may be reduced by the avoided costs of the building materials and labor they replace. Design considerations for BIPV systems must include the building's use and electrical loads, its location and orientation, the appropriate building and safety codes, and the relevant utility issues and costs.

Steps in designing a BIPV system include:

  1. Carefully consider the application of energy-conscious design practices and/or energy-efficiency measures to reduce the energy requirements of the building. This will enhance comfort and save money while also enabling a given BIPV system to provide a greater percentage contribution to the load.

  2. Choose Between a Utility-Interactive PV System and a Stand-alone PV System:

    • The vast majority of BIPV systems will be tied to a utility grid, using the grid as storage and backup. The systems should be sized to meet the goals of the owner—typically defined by budget or space constraints; and, the inverter must be chosen with an understanding of the requirements of the utility.
    • For those 'stand-alone' systems powered by PV alone, the system, including storage, must be sized to meet the peak demand/lowest power production projections of the building. To avoid over sizing the PV/battery system for unusual or occasional peak loads, a backup generator is often used. This kind of system is sometimes referred to as a "PV-genset hybrid."
  3. Shift the Peak: If the peak building loads do not match the peak power output of the PV array, it may be economically appropriate to incorporate batteries into certain grid-tied systems to offset the most expensive power demand periods. This system could also act as an uninterruptible power system (UPS).

  4. Provide Adequate Ventilation: PV conversion efficiencies are reduced by elevated operating temperatures. This is truer with crystalline silicon PV cells than amorphous silicon thin-films. To improve conversion efficiency, allow appropriate ventilation behind the modules to dissipate heat.

  5. Evaluate Using Hybrid PV-Solar Thermal Systems: As an option to optimize system efficiency, a designer may choose to capture and utilize the solar thermal resource developed through the heating of the modules. This can be attractive in cold climates for the pre-heating of incoming ventilation make-up air.

  6. Consider Integrating Daylighting and Photovoltaic Collection: Using semi-transparent thin-film modules, or crystalline modules with custom-spaced cells between two layers of glass, designers may use PV to create unique daylighting features in facade, roofing, or skylight PV systems. The BIPV elements can also help to reduce unwanted cooling load and glare associated with large expanses of architectural glazing.

  7. Incorporate PV Modules into Shading Devices: PV arrays conceived as "eyebrows" or awnings over view glass areas of a building can provide appropriate passive solar shading. When sunshades are considered as part of an integrated design approach, chiller capacity can often be smaller and perimeter cooling distribution reduced or even eliminated.

  8. Design for the Local Climate and Environment: Designers should understand the impacts of the climate and environment on the array output. Cold, clear days will increase power production, while hot, overcast days will reduce array output;/p>

    • Surfaces reflecting light onto the array (e.g., snow) will increase the array output;
    • Arrays must be designed for potential snow- and wind-loading conditions;
    • Properly angled arrays will shed snow loads relatively quickly; and,
    • Arrays in dry, dusty environments or environments with heavy industrial or traffic (auto, airline) pollution will require washing to limit efficiency losses.
  9. Address Site Planning and Orientation Issues: Early in the design phase, ensure that your solar array will receive maximum exposure to the sun and will not be shaded by site obstructions such as nearby buildings or trees. It is particularly important that the system be completely unshaded during the peak solar collection period consisting of three hours on either side of solar noon. The impact of shading on a PV array has a much greater influence on the electrical harvest than the footprint of the shadow.

  10. Consider Array Orientation: Different array orientation can have a significant impact on the annual energy output of a system, with tilted arrays generating 50%–70% more electricity than a vertical facade.

  11. Reduce Building Envelope and Other On-site Loads: Minimize the loads experienced by the BIPV system. Employ daylighting, energy-efficient motors, and other peak reduction strategies whenever possible.

  12. Professionals: The use of BIPV is relatively new. Ensure that the design, installation, and maintenance professionals involved with the project are properly trained, licensed, certified, and experienced in PV systems work.

Application

Photovoltaics may be integrated into many different assemblies within a building envelope:

  • Solar cells can be incorporated into the facade of a building, complementing or replacing traditional view or spandrel glass. Often, these installations are vertical, reducing access to available solar resources, but the large surface area of buildings can help compensate for the reduced power.

  • Photovoltaics may be incorporated into awnings and saw-tooth designs on a building facade. These increase access to direct sunlight while providing additional architectural benefits such as passive shading.

  • The use of PV in roofing systems can provide a direct replacement for batten and seam metal roofing and traditional 3-tab asphalt shingles.

  • Using PV for skylight systems can be both an economical use of PV and an exciting design feature.

 

Kromatix™

Adding Colour to the Solar Industry

Colour treated glass for photovoltaic (PV) and thermal panel applications involves the application of highly efficient and environmentally friendly nanotechnology surface treatments optimized for solar energy (photovoltaic and thermal). This means our product has no paint or tint, but atomic deposition transforming the solar glass into colour. Kromatix™ technology offers vast new opportunities combining full architectural design flexibility and unparalleled panel aesthetics with optimum panel performance for solar building integration.

Application

Kromatix™ can be applied to a large variety of solar powered products and technologies. For facade applications we currently experience the highest demand in Glass/Glass solar (PV) panels (slideshow) because of their superior aesthetics. Kromatix™ is available in six colours, Grey, Blue, Blue Green, Orange, Bronze and Brass. Kromatix™ glass is the front glass layer of a solar (PV) panel and is laminated at the panel manufacturers factory. SwissINSO can deliver the glass stand alone or deliver complete coloured solar (PV) panels in various sizes and thicknesses.

Kromatix™ Technology

Kromatix™glass is obtained by combining two different surface treatments:

Kromatix™ can be applied to a large variety of solar powered products and technologies. For facade applications we currently experience the highest demand in Glass/Glass solar (PV) panels (slideshow) because of their superior aesthetics. Kromatix™ is available in six colours, Grey, Blue, Blue Green, Orange, Bronze and Brass. Kromatix™ glass is the front glass layer of a solar (PV) panel and is laminated at the panel manufacturers factory. SwissINSO can deliver the glass stand alone or deliver complete coloured solar (PV) panels in various sizes and thicknesses.

Colour Principle

The colours of nature all around us are produced by different aspects of the interaction of light with matter. The most common is light interacting with coloured pigments and dyes which absorb and reflect certain light wavelengths. Colour has however sometimes a purely physical origin as created by diffraction or interference of light. It is a known fact that many butterflies obtain their colour thanks to interference phenomena. Applying this technique to solar glass a good compromise has to be found, as the higher the reflectance, the lower the transmittance and the energetic performance of the solar device on which the coloured glass cover is installed. This is why the colour changes as the angle changes.

Kromatix™ and Solar Panel Performance

The IFT Certified Kromatix™ Solar Glass is available in various colours. There are no paints nor tints used to colour the glass therefore it remains stable with time and sun exposure and thanks to the unique Kromatix™ technology average transmittance is between 85% and 90% colour depended. The colored solar glass is produced in various dimensions and thicknesses, can be processed in the same way as standard solar glass in order to fit the customer production process.