The sun as we know
rises in east and sets in west. Additionally, it also changes is position
(season wise) in sky with respect to a fixed point on earth. The orientation of
solar module may be defined by two parameters namely azimuth and tilt angle.
Tilt angle of solar module is defined as angle between the horizontal ground
and the solar module. Azimuth angle of solar module is an indicator of
alignment of the module with respect to (true) south. For modules facing (true)
south this angle is Degree and for module facing (true) north this angle is +/-
180 Degree.
The
most common methodology of module orientation and the most efficient one
wherein the module is oriented in southwards direction. With southwards
orientation, sun can be tracked to its maximum limit, thus generating maximum
energy. However, a major drawback with this type of orientation is that it
requires a larger area and also leads to shadow losses. To reduce shadow
losses, system needs to be designed in such a way that no solar plates in one
row cast a shadow on another at any point of time. With this orientation, the
tilt angle widens, increasing the pitch and reducing the available space. Modules
installed in southward orientation are favorable for places with high energy
demand.
East-
west orientation of modules is the best method to optimally utilize the
available space. On flat roofs, this orientation has the capability of
maximizing the number of PV modules in a way that they don’t cast a shadow on
each other. Through this method, solar PV systems can be installed on
East-West-oriented (E-W) or slanted roofs as well.
Advantages
of E-W Orientation
- More Installed Capacity
Over 20-30 percent more capacity can be
installed in the given area. This is because only walking space is left between
the arrays instead of shading elimination.
- Higher yield per sq. m
Since higher capacity installed in a
given area therefore there would be higher yield.
- Even distribution
The generation of east facing modules
would be a mirror image of modules facing west. This would form a bell curve,
distributing the generation evenly.
Advantages
|
Disadvantages
|
More Capacity
in specified area
|
High mismatch losses
|
Higher
generation per sq. meter
|
Lower specific production
|
Even
distribution of generation
|
Increase in number of inverter
|
Reduction in
Wind Load
|
Lower Return on Investment
|
Below
are the results of simulation run through PVsyst:
E-W Orientation
South Orientation
To
conclude it is important to check and verify the feasibility of the orientation
used in module installations. Before finalizing the orientation, it is critical
to understand the load profile calculations and building architecture. In case
of a challenging building architecture and energy demands/costs, East-West
orientation may fetch attractive results. It is true that E-W orientation
substantially increases the DC capacity of installations by nearly 33 percent
on the same size of roof than southward orientation and also results in
considerable amount of power generation. E-W orientation can definitely prove
to be a useful method in harvesting solar energy on challenging rooftop structures.
