Building-integrated photovoltaic (BIPV) electric power systems not only produce electricity, they are also part of the building. For example, a BIPV skylight is an integral component of the building envelope as well as a solar electric energy system that generates electricity for the building. These solar systems are thus multifunctional construction materials.
The standard element of a BIPV system is the PV module. Individual solar cells are interconnected and encapsulated on various materials to form a module. Modules are strung together in an electrical series with cables and wires to form a PV array. Direct or diffuse light (usually sunlight) shining on the solar cells induces the photovoltaic effect, generating unregulated DC electric power. This DC power can be used, stored in a battery system, or fed into an inverter that transforms and synchronizes the power into AC electricity. The electricity can be used in the building or exported to a utility company through a grid interconnection.
A wide variety of BIPV systems are available in today’s markets. Most of them can be grouped into two main categories: facade systems and roofing systems. Facade systems include curtain wall products, spandrel panels, and glazings. Roofing systems include tiles, shingles, standing seam products, and skylights. PV modules can be designed as aesthetically integrated building components (such as awnings) and as entire structures (such as bus shelters). BIPV is sometimes the optimal method of installing renewable energy systems in urban, built-up areas where undeveloped land is both scarce and expensive.
Building-Integrated Photovoltaic modules are available in several forms.
- Flat roofs:-The most widely installed to date is a thin film solar cell integrated to a flexible polymer roofing membrane
Pitched roofs :
- Modules shaped like multiple roof tiles.
- Solar shingles are modules designed to look and act like regular shingles, while incorporating a flexible thin film cell.
- It extends normal roof life by protecting insulation and membranes from ultraviolet rays and water degradation. It does this by eliminating condensation because the dew point is kept above the roofing membrane.
Facades can be installed on existing buildings, giving old buildings a whole new look. These modules are mounted on the facade of the building, over the existing structure, which can increase the appeal of the building and its resale value.
Glazing:-(Semi)transparent modules can be used to replace a number of architectural elements commonly made with glass or similar materials, such as windows and skylights.
The fundamental first step in any BIPV application is to maximize energy efficiency within the building’s energy demand or load. This way, the entire energy system can be optimized. Holistically designed BIPV systems will reduce a building’s energy demand from the electric utility grid while generating electricity on site and performing as the weathering skin of the building. Roof and wall systems can provide R-value to diminish undesired thermal transference. Windows, skylights, and facade shelves can be designed to increase daylighting opportunities in interior spaces. PV awnings can be designed to reduce unwanted glare and heat gain. This integrated approach, which brings together energy conservation, energy efficiency, building envelope design, and PV technology and placement, maximizes energy savings and makes the most of opportunities to use BIPV systems.
Transparent and translucent photovoltaics:
Transparent solar panels use a tin oxide coating on the inner surface of the glass panes to conduct current out of the cell. The cell contains titanium oxide that is coated with a photoelectric dye.as such organic PV as shown in the figure they can be matched according to building design.
Most conventional solar cells use visible and infrared light to generate electricity. In contrast, the innovative new solar cell also uses ultraviolet radiation. Used to replace conventional window glass, or placed over the glass, the installation surface area could be large, leading to potential uses that take advantage of the combined functions of power generation, lighting and temperature control.
Another name for transparent photovoltaics is “translucent photovoltaics” (they transmit half the light that falls on them). Similar to inorganic photovoltaics, organic photovoltaics are also capable of being translucent.
If PV is to become a well-accepted technology readily available for architects, the building industry, and property owners, integration concepts will have to meet regular building quality standards. This can be achieved by fully integrating the PV system into building materials and by integrating the construction process of BIPV systems into the building construction process. Building integration must include integration into the contractual framework and the organizational structure of building projects.
Architectural criteria for the review of PV buildings and integration products:-
• Natural integration and visually acceptable
• Architecturally pleasing and visually pleasing
• Good composition between materials and colors
• Fit the grid, harmony, composition
• Appropriately links with the context of the project
• Well-engineered and designed
• Innovative new design