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Impact of Shade on Solar Panels and how to reduce its impact on the power plant?

The performance of the solar PV Panel is significantly impacted by shading. A shadow cast on even just part of one solar panel in your solar array can potentially compromise the whole system's output. Here we discuss, the ways one can reduce the impact of shading.


Sun Path in Northern Hemisphere-

During the summer, the days are long, and the Sun is high in the sky. The figure at the top shows the path of the Sun through the sky on the longest day of the year, June 21. On June 21, the Sun rises to the north of east and sets to the north of west, allowing it to be in the sky for an extended period.


During winter, the days are short, and the Sun is low in the sky. The shortest day of the year falls on December 21 when the Sun is lowest in the sky, as shown in the diagram. Each day after December 21, the Sun's path becomes a little higher in the southern sky.


Solar photovoltaic modules must have a clear view of the sky during the solar window, from 9 AM to 3 PM, when the maximum solar radiation is captured.


If possible, one should try to keep the panels, shadow-free the entire day from 6 AM to 6 PM, to gain the maximum performance from the PV System.


If the long winter shadows on December 21 (when the Sun has its lowest altitude) do not shade the solar PV module, the solar PV panels will be free of shade for the rest of the year.

As you can observe, the shade from the objects along the west side of the array is cast on the panels post 3 PM.

This kind of setup can cause many losses, especially with a string inverter, where each panel is a single point of failure. Even though the impact of shadows during this time frame in a single day is low, these losses start accumulating over time.


So if possible, it's always recommended to keep the panels free from any shadows during any time of the day.


Preventive Measures-

1. Elevation-

An elevated structure can not only prevent the shade on the solar panels depending on the site, but it can also double up as a pergola.


2. Inverter Selection-

In Shadow prone sites where elevation is not possible due to site conditions, it's recommended to choose Inverters with DC Optimizers or Microinverters instead of String Inverters as these can still maintain optimum generation is such conditions.