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Orientation

The orientation of the surfaces chosen for photovoltaic integration is an important planning criterion. Even if planning is not geared to yield alone, module orientation should nevertheless be taken into account. Modules oriented south with an inclination of approx. 35° from horizontal allow maximum solar yield (in Central Europe) on the annual average. However, deviations from south-east to south-west only entail minor loss of yield. Even a vertical south-facing installation achieves almost 3/4 of the radiation compared with the ideal orientation (source: WM Baden-Württemberg).

The following diagram helps gauge the increase and decrease in insolation depending on orientation.

Figure 1: : Influence of orientation on annual insolation for Central Europe. 100% energy yield at approx. 35° inclination facing south.

Source: IEA, PVPS

Surfaces inclined more than 12% are self-cleaning with regard to snow, dust and leaves. Loss of yield due to soiling generally ranges between 1 and 5%. The self-cleaning effect increases the greater the inclination.

Last page update: 25.01.2011