South VS East-West orientation

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.