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Shading solar panels calculations

Shading solar panels calculations

In order to have a good performance of the solar panels, we must calculate the shading as accurately as possible to avoid a decrease in the conversion of sunlight into electricity.

Shading solar panels calculations

Did you know that it is very important to make good calculations and analysis of shadows so that our photovoltaic modules are not shaded by the effect of the sun? shading solar panels calculations

The importance of making a good shadow calculation

There are times when the sun makes the shadows longer, this can cause the photovoltaic modules to be shaded if we do not do a good calculation and analysis of the shadow.

If we refer to the northern hemisphere of our planet, the solstices are the times of the year when the sun reaches its lowest height (inclines to the south) and its greatest height (inclines to the north).

The winter solstice occurs on December 21 and the summer solstice on June 21.

Calculation and analysis of shadows  for solar panels in Winter and Summer

Calculation and analysis of shadows  for solar panels in Winter and Summer
The winter solstice is the date when the sun tilts further south and  the shadows are longer  than on other dates.

When the summer solstice occurs, the sun reaches its highest point in the northern hemisphere and  the shadows are reduced .

Due to these events, care must be taken that the photovoltaic modules are not shaded and not guided by a specific date. The technique that we must follow is to  take care of the shadows that occur during the winter solstice , once this shadow is avoided, the solar panels will not be shaded at any time of the year.

How to predict the shadows on our solar panels through an App or online?

An App that I personally recommend is the  Sun Seeker . In this application you can observe the trajectories of the sun in the solstices, even on any date and at any time in a certain place. Working with the cell phone camera we see the path of the sun in real time, on the screen some lines are shown which represent the solstices.

By positioning the camera with reference to the solar panel to be installed, we can see the path of the sun at the winter solstice, the most critical shadow throughout the year. If a building, tree or structure casts a shadow, it can be predicted before installation.

Another way to do solar shadow calculation

One way to  calculate the shadows of the solar panels  manually is by using a mathematical formula, which gives you the minimum distance ( dmin ) that the photovoltaic modules can have apart. The only data you need is the latitude angle of the place and the degrees that the sun tilts with respect to the equator at the winter solstice (since at that solstice we have the most critical shadow), this inclination is 23.5 degrees.

To perform an exercise of this calculation of shadows we can follow these three steps:

  1. Calculate the angle θz based on the latitude angle of the location.
  2. Calculate the angle ɣs. this angle will give you the most critical shadow you will have all year when the winter solstice strikes on December 21st.
  3. Apply the formula of minimum distance between modules (ddim) which is shown in the figure, where:
    β=  the angle of inclination of the module.
    b=  the length of the photovoltaic module
    ɣs=  is the critical angle at the winter solstice

In one way or another, we must avoid  shadows on the photovoltaic modules , since these can generate very large losses in the photovoltaic array and even cause a fire. The tools for a photovoltaic installer are accessible, it’s just a matter of applying them.