BIPV - Building Integrated Photovoltaic

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CIEMAT office building

Opake Fassade
Zwischen 2013 und 2018
IEA PVPS Task 15
CIEMAT office renovation with BIPV cladding (© CIEMAT)
Avda. Complutense 40, 28040 Madrid, Spanien

This public building hosts the headquarters of the Renewable Energies Division of Ciemat. It was built in two stages between the years 1970-1980, and some decades after has suffered from a series of quite serious structural problems. This led to undertake an integral rehabilitation. Once solved the stability problems, rehabilitation of the roof was then undertaken, later the façades, and finally the interior spaces. The BIPV system was integrated in the new ventilated façades. Arch. Juan Carlos Gutiérrez (Architecture & Project Unit of Ciemat), met the PV researchers involved and the PV installer company Ehiso several times before the final project. The installer was responsible for the administrative formalities to legalize and register the photovoltaic system, a process that concluded in July 2015. The installation was legalized by the body in charge of the electrical installations in the Autonomous Community of Madrid.

Ästhetische Integration

The BIPV system is integrated into the ventilated façade of the three-story building. The building is located at the Ciudad Universitaria Campus in Madrid, and it is visible from the access road and the main avenue. The PV modules are combined with the polymer concrete panels used on the façades, achieving a good integration from an aesthetic point of view thanks to the similarity of colors and shapes. However, the integration has not sought to conceal the photovoltaic modules; rather it has been considered that making them visible has a positive effect and provides a modern, exemplary image. (Arch. Juan Carlos Gutiérrez - Architecture & Project Unit of Ciemat)

Energietechnische Integration

The rated energy of the BIPV system is 20 MWh/year. The PV modules are distributed over the south, east and west facades, to achieve a flatter generation curve throughout the day, contributing to feed the building’s baseline load along the year. All the energy generated is instantaneously self-consumed in the building, which means a self-consumption index of 100 %.

Technologische Integration

The BIPV system is made of large standard high efficiency PV modules, made of glass/EVA/PV cells/EVA/white PVF. The PV modules (SunPower E18-305W and E20-327W) form part of two photovoltaic installations: one of 27.2 kWp connected to the building’s local electric power grid, and another stand-alone of 4.8 kWp. They occupy a total surface area of about 172.9 m², replacing conventional construction elements on the upper areas of the east, south and west façades. They are back ventilated (not tight air chamber of about 100 mm). The east façade PV system is divided into three sub-systems to reduce losses due to partial shading caused by nearby trees. The PV modules are fixed to a galvanized steel support structure, in parallel to that of the rest of the façade.

The PV system was provided with the “zero injection” device that prevents PV energy from being dispatched to the electric power grid outside the building, in compliance with the Spanish legislation at the time of the renovation. The device monitors the electrical network and photovoltaic inverters at all times to modulate photovoltaic production in relation to electrical consumption in order not to send energy to the grid. (Javier Pérez, PV installer)


The decision of integrating PV into the building façade was led by the architect of the center, Juan Carlos Gutiérrez, in charge of the rehabilitation project, and supported by the General Director of CIEMAT, the Director of the Renewable Energies Division and the Photovoltaic Unit. The building had to be retrofitted after the technical municipal inspection, and the ventilated façade for the outer envelope of the building appeared as the most suitable option. The retrofit building would become a showcase of the inside i+D activities and, at the same time, demonstrate one easy to reproduce BIPV solution.

The type of material for the ventilated façade was defined on the basis of the PV modules’ characteristics, seeking a product that would allow for similar dimensions, such that someday, if necessary, the PV panels could be interchanged without detracting from the general appearance of the whole of the façade, and adapting the modulation and the general appearance to these elements such that the integration would be as effective as possible. (Arch. Juan Carlos Gutiérrez - Architecture & Project Unit of Ciemat)

Gesammelte Erfahrung

There are no subsidies or economic incentives, but the installation saves energy consumption from the grid: it is a 100 % self-consumption case. The total cost of the installation, including maintenance and reposition of the PV inverters (once in 30 years), is 2.7 €/Wp. Discounting the cost saved in conventional façade, the net cost of the BIPV installation becomes 1.84 €/Wp.

This is an example of a non-expensive, easy- to-implement good architectural solution for building retrofit with standard PV modules integrated in a new ventilated façade. The effect of shadowing caused by the nearby trees may be significant, so if not possible to avoid, at least divide the system in different parts to reduce energy losses.



Opake kalte Fassade


Modul Typologie: 
Standard Module
Monocrystalline Silicum
Nennleistung [kWp]: 
Systemgrösse [m²]: 
Modulgrösse [mm]: 
1046 x 1559
Osten, Süden, Westen
Neigung [°]: 


Gesamtkosten [€]: 
76 000




Avda. Complutense 40, 28040 Madrid, Spanien

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