Building-integrated photovoltaic
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Building-integrated photovoltaics (BIPV) are increasingly incorporated into new domestic and industrial buildings as a principal or ancillary source of electrical power,[1] and are one of the fastest growing segments of the photovoltaic industry.[2]
Typically, a photovoltaic array is incorporated into the roof or walls of a building. Roof tiles with integrated PV cells can now be purchased. Arrays can also be retrofitted into existing buildings; in this case they are usually fitted on top of the existing roof structure. Alternatively, an array can be located separately from the building but connected by cable to supply power for the building.
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[edit] Grid-connected installations
The largest BIPV installations are grid-connected systems. These systems are connected to the utility grid through a direct current to alternating current (DC-AC) inverter. When the load required in the building is more than that supplied by the PV array then electricity will be drawn from the grid; conversely when the PV array is generating more power than is needed in the building then electricity will be exported to the grid. Batteries are not required and standard AC electrical equipment may be used.
[edit] Off-grid installations
Where a building is at a considerable distance from the public electricity supply (or grid) - in remote or mountainous areas – PV may be the only possibility for generating electricity, or PV may be used together with wind and/or hydroelectric power. In such off-grid circumstances batteries are usually used to store the electric power.
[edit] Costs and incentives
The average lowest retail cost of a large PV module declined from USD 7.50 to USD 4 per watt between 1990 and 2004. However, prices have gone up 15-20% in 2005-2006 due to increased demand (mainly due to increased incentives and subsidies) and silicon shortages. The silicon shortage is expected to persist until at least 2008. With many jurisdictions now giving tax and rebate incentives, and/or net metering solar electric power can now pay for itself in ten to twenty years in a few places.
[edit] Technology
BIPV panels are a sandwich element composed of two metallic corrugated and ribbing sheets and, inside, of high-density polyurethane foam. The panel has a profile specifically designed to insert a custom-made photovoltaic module, considering the indispensable ventilation requirement on the rear surface of the module. Through the interstice an optimal level of working temperature is ensured for the system and the different thermal expansions are respected.
[edit] National developments
[edit] United Kingdom
In August 2006 there was widespread news coverage in the United Kingdom of the major high street electrical retailers (Currys) decision to stock PV modules, manufactured by Sharp, at a cost of one thousand pounds sterling per module. The retailer also provides an installation service. The Energy Saving Trust that administers UK government grants for domestic solar power systems estimates that an installation for an average-sized house would cost between £8,000 and £18,000, and yield annual savings between £75 and £125.[3]
[edit] See also
[edit] External links
- Wisconsin Public Service Corporation: Building-Integrated Photovoltaics (buildingsolar.com)
- Building Integrated Photovoltaic system
- Kansas Solar Electric Co~operatives
- Book: ElectriCity - Beyond the curve of deregulation
[edit] References
- ^ buildingsolar.com: Building-Integrated Photovoltaics, Wisconsin Public Service Corporation, accessed: 2007-03-23.
- ^ Terrasolar, accessed: 2007-03-23.
- ^ High street solar panels on sale, BBC online news, published: 2006-08-01, accessed: 2007-03-23.
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