One row of solar PV modules can cause a shadow over the other row if the adequate inter-row spacing is not considered while designing or planning the system. Inter-row shadow can cause lower generation output from the PV array and may also damage the PV modules by developing Hot Spots.

In this article we will discuss on how to determine module inter-row spacing for flat rooftop solar PV systems using mathematical formula.

To get familiar with the basics of shadow analysis, we recommend you to go through our previous article “How to conduct shadow analysis without using expensive simulation tools?”

Mathematical Formula: Inter-Row Distance Calculation

Since the rows are placed in North-South direction, the below formula should be used to calculate Inter-Row Distance:

Inter – Row Distance (m) = H (m) x [Cos (Azimuth) / Tan (Altitude) ]

To calculate height of the Module, below mentioned formula to be used:

Height of Module (m) = Module Length (m) x Sin (Module Tilt)

Note: Azimuth and Altitude angles for a particular location and time can be taken from freely available websites such as: or

To understand this better let’s have a look at an example on the next page

1 Comment

Divya Dhankhar · November 18, 2020 at 3:40 am

Great article! Easy to comprehend.

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