Growing dependencies promote the need for alternative energy sources, and the Sun is our primary source. Its potential is limitless. Every day, the Sun provides us with more than 10,000 times the energy we need.
A major concept of The B&W House is to maximize solar power. Therefore the surface of the roof is the maximum permitted in the Solar Decathlon 2009 Competition. The roof and all the fašades are cladded with photovoltaic (hereafter PV) modules.
The Roof is self-orientating along the day, following the sun. It is a solar tracking system connected to the automation system of the House. This maximizes its energy production. Moving the PV roof gives 10.3% extra power compared to a fix roof oriented to the south.
The PV roof contains high efficiency modules of 220 Watts peak each. The design of the structure of the movable roof is based on the dimension of the PV modules.
Parts of the photovoltaic system: the PV modules (11 kWpeak), wiring, electronic solar switches (AC and DC), bi-directional meters and PV panel box.
Three inverters (10.4 kWnominal) transform the Direct Current (DC) produced by the panels into Alternating Current (AC).
The PV modules of the roof are divided into six series connected to three inverters.
The annual solar production depends on the solar position and the total hours of Sun. See the diagram below: summer in red, autumn and spring in green, winter in blue.
See the diagram below: summer in red, autumn and spring in green, winter in blue.
Our roof has an inclination of 15 degrees to improve its behaviour according to the solar conditions.
The total energy produced by all the PV panels of the House will inject every year 19,345 kWh (16,247 kWh from the roof) into the electric grid.
We have calculated the PV roof production during a single day of the contest week in October depending on the weather based on the IESNA.
A cloudy day ( > 70% overcast and < 10.000 lux) 28.06 kWh.
A partially cloudy day (30-70% and 100,000-10,000 lux) 36.36 kwh.
A clear day ( < 30% a nd > 100,000 I ux) 53.18 kWh.
The PV roof is one of the patents that the B&W House introduces in the Solar Decathlon 2009.
The structure of the self-orientating roof is moved through cables controlled by the automation system, The roof consists of an inverted pyramid, this relies onto another pyramid In the center of the roof.
The junction of both pyramids, where the PV roof relies, is the so called ball-and-socket joint, and permits to rotate the PV roof.
It is the total photovoltaic energy delivered to the grid during one year per installed kw of power. Units are kWh per kW peak installed.