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How to calculate the inclination of a solar panel?

How to calculate the tilt of a solar panel? The tilt is a very important factor in the efficiency of the solar panel, with an optimal tilt the panel will have its maximum production.

How to calculate the inclination of a solar panel?

The angle of a solar panel varies depending on which part of the world it is in since solar panels produce most of their power when the sun shines directly on them. We have to take into account that the sun moves across the planet from East to West, and it will be low or high depending on the time of day and the season of the year. For this reason, in order for the greatest amount of sun to fall on the panel throughout the day, the sun must be set in the direction in which the panels are oriented and an optimum angle of inclination must be calculated.

These conditions depend on the following characteristics:

  • Installation location.
  • Time of year in which the location is located.

1.- Calculation of the optimal angle of the solar panel

As a general rule, solar panels should be more vertical during the winter to get the most winter sun, and more inclined during the summer to maximize output from the solar array. Here are two simple methods to calculate the approximate angle of the solar panel according to your latitude.

1.1.- Calculation method 1

The optimum tilt angle is calculated by adding 15 degrees to latitude during winter and subtracting 15 degrees from latitude in summer. For example, if the latitude is 34⁰, the optimal tilt angle for solar panels on site during winter will be 34⁰ + 15⁰ = 49⁰. On the other hand, the optimal inclination angle for summer will be 34⁰ – 15⁰ = 19⁰.

1.2.- Calculation method 2

This method is an improvement on the first method shown above, therefore the results are more reliable than Method 1. In this method, the optimal tilt angle for solar panels during winter is calculated by multiplying the latitude by 0, 9 and then adding 29⁰. For example, choosing a latitude of 34⁰, the angle of inclination will be given by the result of the following equation:

34⁰ x 0.9 + 29⁰ = 59.6⁰

This angle is 10⁰ steeper than in the general method, but very effective for taking advantage of the midday sun, since it is when the sun hits the solar panels the most. However, for summer the angle of inclination is calculated by multiplying the latitude by 0.9 and subtracting 23.5⁰. For example, choosing an inclination of 34⁰ the following result is obtained:

34⁰ x 0.9 + 23.5⁰ = 7.1⁰

On the other hand, to get optimal tilt angles during spring and fall, 2.5⁰ is subtracted from the latitude.

1.3.- Inclination on the roofs

One of the peculiarities to take into account is that when a solar panel is installed on a roof that has a fixed slope, it is not necessary to change the angle of the roof to obtain optimal production since this will make the solar installation more expensive. Before carrying out the installation, it is advisable to carry out a study on whether the installation on a roof is profitable. In Spain, roofs usually have a slope between 5% and 10%, which is usually optimal for a solar installation.

2.- What inclination is optimal?

Although the optimum inclination of the solar panels varies according to the time of year, a photovoltaic solar installation cannot vary its inclination, unless it has a 1 or 2-axis steering system. These systems have very high prices and are only profitable in solar farms.

For everyday cases, for example, the installation of panels in our home; An optimal inclination is made for the time in which we are going to give the installation the most use. For example, if it is a vacation home, it will be sized so that the inclination is optimal in summer, assuming that it is the time when we will spend the most time there.

Likewise, the regulations of each country must be taken into account. In Spain, it is stated in the Technical Specifications for Grid-Connected Installations that the orientation and inclination of the photovoltaic generator and the possible shadows on the panels must be less than the threshold, which in general is 10% and including shadows, not may exceed 15%.

Read more: The Best Orientation For Your Solar Panels