A shadow falling on a solar PV module blocks the flow of solar energy and eventually, the modules generate hotspots/gets damaged through rise in temperature. The shadow could be on the nearby trees, buildings or even the PV module array installed ahead. The efficiency of a PV module at any time reduces in direct proportion to the area of the shadowed part of the module, therefore it becomes highly important to conduct shadow analysis during the feasibility study and designing a rooftop solar power plant.
The shading experienced in solar PV plants can be identified as follows:
- Self-shading- the shadow that occurs on a PV module due to another PV module.
- Shading due to near objects – the shadow that occurs due to nearby objects which may be present within the vicinity or rooftop, around the installed PV modules. Some of these may affect the plant for a certain time of the day or for the entire day depending on their location, height, distance from the solar module.
The shadow that may occur due to far away obstructions like newly built highrise buildings, towers etc. that may cast shadows on the solar power plant. Such situations are rare and at times unpredictable for the future.
Identifying a PV array location
When designing a solar system there is often the need to understand how long a shadow will be so that row spacing between solar PV modules can be properly designed. Keeping in mind that the sun travels in an arch across the sky so both the sun’s altitude position and the azimuth must be accounted for when determining the length of a shadow.