Conducting shadow analysis is a necessary step while planning for a solar PV rooftop project. Solar PV modules on a rooftop can be shaded by nearby trees, nearby buildings, overhead tanks, AC outlets, parapets, mumty’s etc.
If a shadow falls over a solar PV module, it will cause lower generation output and may also damage the solar PV module
It is not always possible for small solar EPC players and startups to buy expensive simulation softwares to conduct shadow analysis and plan a small residential or commercial solar PV rooftop project.
In this article, we will discuss on how to conduct shadow analysis using mathematical formulas.
Basics of Shadow Analysis
Shadow length of an object depends on two major factors:
- Position of Sun in the sky
- Height of the object
For an object of height “H” as shown in figure, Shadow Length is calculated:
Shadow Length = H(m) / Tan (Altitude)
A taller object in the Eastern side of the proposed solar PV array location, will cast shadow during the Morning time in the West direction. The same is shown in the below images:
Similarly, a taller object in the Western side of the proposed solar PV array location, will cast shadow during the Evening time in East direction. The same is shown on the below images:
A taller object in the Southern side of the proposed solar PV array location, will cast shadow during both Morning and Evening time in East and West direction. The same is shown in the below images: