H Influence Of Alignment, Inclination And Shading - Viessmann Vitovolt 200 Technical Manual

1.3 Photovoltaic system
Influence of alignment, inclination and shading
North
West
South
Example:
30°; 45° south−west
Optimum alignment and inclination
In Germany, the solar generator provides
the highest solar yield over an annual
average when facing south with an
inclination of approx. 30 to 35 degrees to
the horizontal plane. The installation of a
solar power system is even viable when
the installation deviates quite significantly
from the above (south−westerly to south−
easterly alignment, 25 to 55 degrees
inclination).
The graph illustrates the yield reduction
resulting from an installation of the solar
generator which is less than perfect. A
lower inclination is more favourable if the
solar generator cannot be pointed south.
A photovoltaic system with a 30º slope
and a south−westerly orientation of 45º
still achieves 95% of its optimum yield.
Even with an easterly or westerly
alignment, you can still expect 85% with a
roof inclination between 25 and 40º.
A steeper orientation would be more
favourable in winter, however the system
achieves two thirds of its yield in the
summer months. With a roof inclination
of between 25 and 40º and deviations of
up to 45º from south, the reduction in
returns is negligible. On the other hand,
an angle of inclination less than 20º
should be avoided, otherwise the solar
generator will become contaminated.
6
Annual
irradiation
in %
East
Angle of
inclination
Because photovoltaic systems require
large roof areas, the generator surface
may have to be split over different roof
areas. If these surfaces have different
orientations and slopes, each solar
generator must be operated with its own
inverter to achieve an optimum match
and therefore yield.
However, this is not required if only the
inclination is different.
Shade reduces energy yield
Position and size the solar generator so
that the influence of structures, trees,
power lines, etc. which would shade the
panels, is minimised. Also consider how
neighbouring properties are likely to be
developed or planted up.
Large gaps should be retained between
the generator surface and chimneys or
other objects which throw shadows over
a roof. Aerials and similar movable
objects may be fitted to other parts of the
roof.
VITOVOLT