The most popular photovoltaic panels are rectangular and cover more or less 1 m². The power delivered by each panel is between 250 and 300 watts-peak.
Depending on the space available on your roof, you can add to the number of panels to multiply the total power of your installation. Larger panels also exist which are fitted to the roof in a single frame.
You have already perhaps seen this on some buildings: photovoltaic panels can nowadays also be fitted on façades.
However, the output is lower: the sun's rays do not fall vertically on their surface and there is therefore less sunshine. This lower output can be compensated for slightly by operating a larger surface area.
Important clarification: this type of panel, which can be seen from public areas, requires planning permission . Planning permission is not required, however, for panels built into an existing roof or which cannot be seen from public areas.
As at 1 January 2014, there were 3,013 photovoltaic installations in service in the Brussels-Capital Region, including 2,551 belonging to private individuals.
The vast majority of these installations (2,353 out of 2,551) produce less than 5 kWp of power, i.e. less than 20 m2 for panels of 1 m2 and with a power of 250 Wp.
In Belgium, according to average sunshine and in optimum conditions (south, 35°), a 1 m2, 250 Wp panel produces 225 kWh a year. A total of 4500 kWh a year can be produced with 20 m2, which more than covers the average requirements of a household (about 3600 kWh a year).
In Wallonia and Flanders, most domestic installations exceed 5 kWp, mainly because homes are more extensive with larger roof areas available.
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