Building-Integrated Photovoltaics

Building-integrated photovoltaics (BIPV) are photovoltaic materials that replace conventional building materials in part of the building envelope, such as the roof covering, skylights or facades. Unlike ordinary solar panels mounted on racks above a finished roof, BIPV products act as the roof or wall itself, so part of their cost is offset by the materials and labour they replace.

Roof applications

Roofing holds a larger share of the BIPV market than facades and is generally more productive because of its orientation to the sun. Main roof products are:

• Solar shingles: units shaped and laid like conventional shingles.
• Solar roof tiles: tile-shaped modules, including ceramic tiles with integrated cells; a Dutch company patented a ceramic solar roof tile in 2013.
• Flexible thin-film laminates: adhered to low-slope membranes; copper indium gallium selenide (CIGS) cells have been fused into TPO single-ply membranes.

Roof-integrated PV can also protect the membranes beneath it from UV and water and help keep the dew point above the membrane, reducing condensation.

History

• 1970s: aluminium-framed PV modules were attached to buildings, mostly in remote areas without grid power.
• 1980s: roof add-on systems were demonstrated on grid-connected buildings.
• 1990s: purpose-designed BIPV construction products became commercially available.
• 2005 onward: solar shingles entered the market, followed by products from large roofing and energy companies.

BIPV versus BAPV

Building-applied photovoltaics (BAPV) are PV systems added to a building after construction, such as rack-mounted panels. Many installations described as building-integrated are in fact BAPV.

Challenges

• Heat: integrated modules lose heat less effectively than ventilated rack-mounted panels, so they run hotter, which reduces output and can degrade cells.
• Cost and complexity: higher upfront cost, more complex design and construction, and the need to meet both roofing and electrical codes.
• Awareness: limited familiarity among designers, installers and the public.

Incentives

Some governments have offered extra support for integrated PV. France, for example, paid an extra €0.25/kWh for roof-, wall- or window-integrated systems, and China's Golden Sun programme subsidised up to 50% of investment in eligible projects, including BIPV.