Position the solar panel ?
The efficiency of a photovoltaic module varies with the angle of incidence of the solar rays. The position that you will give to your solar panels will therefore affect production.
The objective of this article is to help you determine the optimal position solar panels for installation in isolated.
The position of a panel is actually :
- son orientation, ou auth, that is to say they will do with the angle the north-south ax dans le plan horizontal.
- its inclination, that is to say that the angle with the horizontal plane will.
Orientation optimale
For orientation, it is relatively simple : as long as the horizon is clear, must orient your solar panel to the south if you are in the northern hemisphere and to the north if you are in the southern hemisphere.
Near the equator, Optimal inclinaison the east roughly the horizontale, thus, the orientation of the solar panel is not really important.
Inclinaison optimale
For a solar installation in isolated, that is to say without connection to an electrical network, optimum inclination is usually the one that optimizes the production of solar panels during the month less sunny. En effet, sizing your panels is based on this month .
So we must begin by determining the sunshine to identify the least favorable month.
Once you know the less sunny months, you get the optimum angle by adding the latitude of the location of your installation the corresponding figure in the table below :
| Jan. | February. | Sea. | April. | more | Jui. | Jui. | Aoû. | Sep. | Oct. | Nov. | December. |
| +13° | +7° | 0° | -7° | -13° | -20° | -13° | -7° | 0° | +7° | +13° | +20° |
This figure is actually the declination of the sun, that is to say the angle a ray of sun makes with the plane of the equator, for each month of the year.
For example, to temperate regions where winter is the worst tilt period chosen is often the latitude plus 10 ° : 60° in Brussels, 50° à Madrid…
Example :
Here is l’irradiation globale one mensuelle moyenne à Kinshasa one Democratic Republic of Congo :
| Jan. | February. | Sea. | April. | more | Jui. | Jui. | Aoû. | Sep. | Oct. | Nov. | December. | |
| Kinshasa | 4.29 | 4.68 | 4.89 | 4.69 | 4.13 | 3.45 | 3.22 | 3.57 | 4.09 | 4.25 | 4.43 | 4.22 |
We see that the worst is July. As Kinshasa is located at a latitude of -4 ° degrees north, the inclination of the panels must be -4 ° 13 ° N = 8.
Note that this is only an estimate : in the case of Kinshasa, the’online tool evaluation program of the European solar resources provides an optimal angle of 6 ° north.
For regions in the vicinity of the equator, the optimum slope is close to zero but it is preferable to provide a slope of at least 5 à 10° your solar panels to facilitate the flow of rainwater and the evacuation of objects and dust which may be deposited on the panel.
And if it is not possible to be optimal…
Depending on your project, it is sometimes impossible to fix your solar panels according to the orientation and / or optimal tilt. This is particularly the case as we have just seen near the equator but also when the panels must be attached to the roof of an existing building, even when they are intended to be used on a boat or other mobile system.
In that event, know that the production of a solar panel decreases slightly if the gap with the optimal inclination is low but that these losses increase rapidly if the deviation exceeds twenty degrees.
Example :
A difference of 10 ° with respect to the optimum inclination causes a lower production under 2%
A difference of 20 ° results in a decrease of approximately 6%
A difference of 30 ° results in a decrease of approximately 14%.
A difference of 40 ° results in a decrease of nearly 25%
