What is the Best Angle for Solar Panels

solar windWhat is the Best Angle for Solar Panels

Best Angle for Solar Panels

Welcome to this information page of MPPT Solar. Do you want to make a solar PV system very efficient but do not know how to evaluate the proper orientation of the solar panels and how to calculate the correct degree of inclination? No problem, on this page you will find all the information and advice that will enable you to learn step by step the correct orientation (azimuth angle) and the optimum angle of your panels (tilt angle) according to the season in which you have more energy requirements and the geographic location where you want to install the solar PV system. In fact, thanks to a practical mathematical formula and our map of Italy latitudes You will learn to calculate the optimum angle in both the summer and in the winter in your town, without wasting time and all for free.

In what direction should be oriented panels?

When designing the PV system is essential to choose the side of the roof on which to mount the panels. We therefore need to know which side is more sunlight throughout the day in order to have the maximum possible energy production. Because the solar panels are more productive when the sun's rays are perpendicular to their surfaces, the best orientation is directly to south (azimuth angle = 0 °).

Optimum Tilt of Solar Panels

In the case that in a southerly direction is not possible to install or have problems of shading (like for example a tree very high) it is possible to slightly vary the orientation of the panels. And 'in fact useful to know that if we orient the panels to the outside of the south, up to a maximum of 45° (south-east and south-west), the annual output is reduced quite low (1-3%). The solar radiation that photovoltaic panels receive is in fact almost the same. However, if the panels are turned at an angle greater than 45 ° with respect to the south, the production starts to decrease considerably. 90 ° from the south (ie directly east and west), the decline in production can reach up to 30%. This decrease is due to the fact that the photovoltaic panels, during most of the day, are affected by sunlight weak and not perpendicular. These panels produce solar energy but certainly to a lesser extent than panels facing directly south.

How many degrees must be tilted panels for maximum energy production?

Well, now that we know that the optimal orientation is south, we find the optimum angle. First, it is good to say that the choice of the inclination of the photovoltaic panels on the roof of a house we are bound to meet two basic needs: the need for energy production and the need for an end result aesthetically pleasing and durable. The roof of a house already has a tilt and inclination for which we must find a compromise between these two needs. Knowing the optimal angle for production will allow us to choose the best compromise for our installation. If you wish to build the structure for a canopy shading with solar panels or a photovoltaic plant on land or for an innovative carport from a string of panels connected in series or parallel, this guide will be very useful in the design phase the structure as it will provide the optimum inclination of the structure with respect to the horizontal plane.

The best angle that will have our solar panels is influenced primarily by two factors:

1)   the latitude of the geographical location where we want to mount them
2)   the time of year we need to have more energy

How does the latitude affect the inclination?

As we mentioned above, plus a photovoltaic panel is tilted perpendicular to the sun and produces more electricity. The maximum production of energy we get at noon, when the sun reaches its maximum height above the horizon. We therefore need to know, throughout the year, the maximum and minimum height of the sun at noon to find out how many degrees tilt our panels. This is why we come to the aid of the special two days.

The Sun's path in the sky

As many already know, there is one day of the year when there is less daylight hours and one day of the year when we have more daylight hours. These are the days of the winter solstice and summer solstice. The summer solstice, when we have more daylight hours, is between 20 and 22 June 21 in the Northern Hemisphere, and the sun at noon is at its maximum annual height (see figure), while the winter solstice, where we have fewer hours light is on 21 or 22 December and the midday sun is at its lowest annual height (see figure). Even according to the latitude in which we find ourselves, change the annual maximum and minimum height of the sun at noon. The latitude of the United States varies by several degrees. To find the height of the sun during the summer solstice and the winter one must identify, by the figure below, how many degrees is the latitude where we want to install the photovoltaic system. For example, if we are in Chicago, the latitude is about 42°.

United States Latitude

Latitude of United States

Calculating maximum height of the sun at midday

Once the latitude, we must subtract 23 ° (angle of inclination of Earth's current approximate). The last math is: 90 - (result). In the case of Chicago we have the point of culmination of the Sun at 71°, obtained from the calculation 90 - (42-23). To obtain the the maximum energy output during the summer solstice, the solar panels in Chicago should be directed to the SOUTH and are inclined at 19° (90-71). In this way, at noon the panels will be perfectly perpendicular to sunlight.

Calculating minimum height of the sun at midday

To calculate the height of the noon sun during the winter solstice, we instead subtract, add 23 °. The mathematical operation will not be affected. The result for Chicago is 90 - (42 +23) = 25°. To obtain the maximum efficiency during the winter solstice, photovoltaic panels in Chicago should be directed to the SOUTH and are inclined at 65° (90-25). In this way, at noon the panels will be perfectly perpendicular to the sun.

Best angle for solar panels in Chicago

In the calculations you immediately notice that a strong inclination to the plane of the panels will encourage greater energy production during the winter, while a slight inclination to the plane of the panels will encourage greater energy production during the summer. What inclination choose for our system? Simple, one that meets our energy needs. If we are in Chicago and we need energy only during the winter you should choose an angle between 53 ° and 65 ° (ie 59 °), while if we need only during the summer is good to choose an angle of 19 ° and 30 ° (example 24.5 °). If instead we have a greater need during the summer is good to have an angle between 19 ° and 42 ° (eg 30 °). If instead we have a greater need during the winter is good to have an inclination between 42 ° and 65 ° (ie 53 °). If our energy needs in Chicago is constant throughout the year then you can opt for something in between, such as 42 °, always oriented to the SOUTH.

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