BIPV - Building Integrated Photovoltaic

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Multi-family house in Appiano

Architectural system: 
Opaque roof
Tilted roof
Building use: 
residential
BIPV costruction year: 
From 2005 to 2012
Source: 
Eurac Research
Multi-family house BIPV roofing system (building owner)
Location: 
Appiano (BZ), Italy

The building’s owner was involved during all process phases, as responsible for the architectural and technical design of the BIPV system. After performing an overall economic assessment and a market survey, he selected the modules. PVEnergy Srl, already known to the client thanks to previous collaborations, was chosen to install the PV plant. Kaneka Corporation is the manufacturer of the modules. The installation was completed in 2007.

Aesthetic integration

The PV system is integrated on four dormers, on the western roof slope of a residential building built in 1977 in the historical town centre of Appiano. It represents an interesting retrofit installation where the dark surfaces of the photovoltaic modules are installed next to the traditional roof tiles. This contrast is not visible from the surrounding building or from the street (building owner)

Energy integration

With a nominal power of 1.92 kWp, the BIPV system covers almost the 70% of the top apartment’s electricity demand thanks to an annual energy production of around 1,900 kWh. The photovoltaic output is especially used for the building conditioning system (building owner).

Technology integration

The BIPV plant is composed of 32 thin-film amorphous silicon standard modules (Kaneka K60). The modules are installed on aluminium planks which are fixed on the dormers’ metal sheets through special grab connectors. This mounting system does not require drilling the metal sheets, ensuring the roofs weather tightness. The natural ventilation of the PV plant is guaranteed thanks to an air gap between the modules and the roof.

Decision making

The building owner decided to install a photovoltaic plant in order to balance the increase of the electricity demand following the installation of a new air-conditioning system. He designed the PV plant as a distinctive in-roofing system, using the existing dormers as support. The purpose was to hide the modules from view, covering the dormers with the same shape and size. In this way, the difference between the plant surfaces and the roof tiles is not noticeable (building owner).

Lesson learnt

The PV integration had good results concerning several aspects. Aesthetically, the designer met the objectives to keep the original homogeneous surface of the pitched roof by placing uniformly the modules on the dormers. A better aesthetic integration could have been performed by closing the air gaps, but the modules are hidden from view so it was not necessary to do so. Economically, the selected module technology (with low efficiency) allowed the photovoltaic plant to stay within the small plant’s category of the Italian energy service management body (GSE). Technically, after the construction work was finished, a minor intervention was required in order to avoid snow damage on the roof gutter (building owner). As a multifunctional technology, BIPV should be designed taking several targets into account (e.g. the ones mentioned above) which have to be balanced according to the main project purposes.

Data

PROJECT DATA

Project type: 
Retrofit
Building function: 
Residential
Integration system: 
Opaque tilted roof

BIPV SYSTEM DATA

Module type: 
Standard modules
Solar technology: 
Thin-film amorphous silicon
System capacity [kWp]: 
1.92
System size [m²]: 
30
Module size [mm]: 
960 x 990
Orientation: 
West
Tilt [°]: 
8

BIPV SYSTEM COSTS

Total cost [€]: 
10,000
€/m²: 
333
€/kWp: 
5,208

DATI PRODUTTORE

Producer: 
Kaneka Corporation
Address: 
Nakanoshima 2-3-18, Osaka, Japan
Contact: 
-

Map

Appiano (BZ), Italy

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