DOCTORAL GRANT GAČR 103-03-H089 SUSTAINABLE CONSTRUCTION OF BUILDINGS AND SUSTAINABLE DEVELOPMENT OF URBAN SPACE
Ing. Kamil Staněk, CTU in Prague, Faculty of Civil Engineering, Department of Building Structures Thákurova 7, 166 29 Prague 6, Czech Republic || Email:
[email protected]
BIPV Systems and Solar Skins
WORKSHOP W2-510
ENERGY MODEL FOR OPAQUE VENTILATED BIPV FAÇADE
Building Integrated Photovoltaics (BIPV) is rapidly developing concept of integration of hi-tech renewable energy systems into building envelopes. BIPV systems can be designed in form of façades, roofs or PV glazing with accent put on full functional, structural and aesthetical integration and cooperation with the building. On-going research project at the Faculty of Civil Engineering, CTU in Prague is aimed at ventilated BIPV façades. Large-scale experimental PV installation will be raised on south-west façade of the faculty. At the same time simulation model is being developed to calculate and predict optimal structural, geometrical and technological parameters of ventilated BIPV façades. welded steel anchor
SURROUNDING SURFACES
Exterior
PV MODULES GLASS COVER
VENTILATED AIR GAP OUTER WALL THERMAL MASONRY INSUL.
BACKSHEET
ventilator
incident solar radiation
ventilated airgap
SOLAR CELLS
absorbed solar radiation
Interior
BUILDING INTEGRATED PHOTOVOLTAICS
thermal energy
wind airflow transmit. absorpt.
optical losses
vertical steel section
electrical energy
- network of solar energy conversion -
horizontal aluminium section
pressure plate
Incident solar radiation on PV modules is either reflected or absorbed by a glass cover and the rest is transmitted to solar cells. A portion of energy absorbed by the solar cells is directly converted into electricity with efficiency of about 15% and the remaining energy is turned into heat.
- vizualization of opaque ventilated BIPV façade designed for the Faculty of Civil Engineering, Building “B” -
Parameters of experimental façade installation Number of modules
176
Type of modules
monocrysralline 105 Wp
Number of PV arrays
3
Total area of PV arrays
150 m
Total output power (at STC*)
18.5 kWp
Number of sensors
90
Tsurr
thermal energy
radiation
radiation
2
forced convection
82 tempereture 6 airspeed | 2 solar radiation
forced convection
conduction
TFV,front
Tcell,1
Tcell,2
TFV,back
Twall
adiabatic boundary
PV panel
*) STC = Standard Testing Conditions
masonry
thermal insulation
- vertical section of BIPV system structure designed for south-west façade of the Faculty of Civil Engineering -
Advanced concept of BIPV systems is Solar Skin which unifies both opaque and semitransparent PV elements together with double-skin façades and ventilated roof systems into architecturally attractive energy generating building envelope.
PRELIMINARY CALCULATIONS OF OUTPUT POWER Calculations of meteorological inputs are based on METEONORM database data. Values of incident solar radiation are recalculated for south-west orientation and 90° tilted façade surface. Calculations of output electrical power are based on Photovoltaic Array Performance Model (Sandia National Labs).
Tair,gap
Tambient
airflow
- network of heat exchange with key nodal temperatures -
Heat, or thermal energy, generated at the cells is conducted simultaneously towards front and back surface of the PV modules. This energy is radiated and convected from the modules surfaces to surroundings or to a ventilated airgap, respectively. Thermal energy from the airgap can be collected and utilized for heating (preheated ventilation air) or cooling (desiccant cooling) of a buildig. q”out,rad
q”in,rad q”out
q”out,conv
q”in
q”in,conv
q”sol,therm
- nodal representation of heat fluxes of the 1D heat transfer model for PV modules -
- input meteorological data and computed electrical power output for the days from 1st to 3rd January -
From the nature of the airflow in the ventilated air gap follows that the speed of moving air can be determined independently of the air temperature, whereas there is strong dependency between solar cells temperature and their efficiency. The overall model then takes meteorological data and airspeed as input variables for computation of thermal and electrical energy output. meteorological model / measured meteorological data
thermal model
airflow model
electrical model
thermal energy output for heating/cooling st
rd
- input meteorological data and computed electrical power output for the days from 1 to 3 July -
www.substance.cz/grant
electrical energy output for grid supply - complex model scheme -
This poster is supported by grant of GAČR 103/03/H089 “Sustainable Buildings and Sustainable Urban Development”
