Building-integrated photovoltaics (BIPV) uses photovoltaic panels in the place of traditional building materials in building structures such as roofs, windows, and facades. Photovoltaic panels generate solar power by converting sunlight to electricity. This renewable, non-polluting source of energy makes building-integrated photovoltaics an integral part of sustainable architecture. Photovoltaic panels are designed into many new construction projects, but they can also be fitted on pre-existing buildings. Many BIPV buildings in countries such as France, Germany, and the United States give energy back to the grid and receive financial incentives for doing so.
Photovoltaics (PV) is a fast growing field of technology due to the growing need and desire for clean energy alternative. A photovoltaic panel can be integrated into a building, or it can be mounted on the ground. These panels or modules house many packaged solar cells, which are made up of several photodiodes that convert natural light into electricity. In a grid-connected PV system, this electricity is then routed into an electricity grid. In a stand-alone system, the energy charges a battery where it can be stored for later use.
The term building-integrated photovoltaics usually implies that the building was planned with PV systems in mind. The photovoltaic industry has designed PV panels for several different purposes and styles, so an architect’s sense of creativity and aesthetics need not be stifled by his desire for sustainability. PV modules come in an array of colors, and may be framed or unframed, opaque, transparent, semi-transparent, flexible, or rigid thin film on metal substrate. Size, shape, and peak voltage can also be customized. The proper panel choice will largely depend on its purpose. Crystalline modules should not be used in areas with high temperatures, as it decreases their efficiency.
The most common type of panel installed is for flat roofs. They can come in the form of solar roof tiles or shingles, or solar modules, which are subdivided into flexible modules, transparent or semi-transparent modules, or thin film modules. Thin film modules have proved the most popular, placing one or more thin layers of solar cells over electrical insulator base called a substrate. Building-integrated photovoltaics also allows for the construction of pitched roofs with either mounted or integrated panels.
PV facades or PV curtain walls, the faces of a building, are built for purposes of energy saving, aesthetics, and weatherproofing. These can be made with traditional, transparent, or semi-transparent modules. Facades can also be equipped with shadowing systems, which tilt the modules to shade the building or to maximize the efficiency of energy harnessing. These modules can be tilted manually or automatically and are sometimes known as “Shadow-Voltaic” systems. Shadowing systems may be integrated into the original building or can be mounted later.
Transparent or semi-transparent PV panels are used to replace traditional building materials, such as glass, in glazing or laminates. In building-integrated photovoltaics, architects often use low-tempered iron glass to sandwich the solar cells. Glazing usually employs thin film cells, monocrystalline cells, or transparent cells between two layers of foil. Some panels allow visible light to pass through the window while using the ultraviolet light to produce energy. Other windows may be tinted for shade, equipped with shadowing systems, or colored.