Photovoltaic solar panels, like any other technological device, do not work the same in every situation. In this case, weather conditions, deterioration or orientation can be key factors in their performance.
For this reason, it is always advisable to get expert advice both in installation and maintenance, so that you can get the most out of your solar panels and make them work as efficiently as possible.
Peak sun hours
The solar resource available in a given location can be measured in various ways, but in the case of solar photovoltaic installations it is usually calculated in peak sunshine hours (HSP). These units reflect the number of equivalent hours, in a given period; usually an average day of the month; during which a solar panel (or any surface), with a certain orientation and tilt, will receive an irradiance of 1000 [W/m2].
That is, how long in a day, a solar panel is receiving the equivalent (between morning and afternoon) of 1000 W/m2 or more.
Solar radiation is measured in this way because the power given by a photovoltaic solar panel depends mainly on the irradiance it receives, which varies greatly throughout the day, and because the manufacturer provides the power data in STC conditions, i.e. with an irradiance of 1000 [W/m2] and at 25 [°C] operating temperature.
Inclination
Giving the panels a certain angle is essential to ensure that the sunlight strikes as directly as possible. As a general rule, it is considered that the angle that best optimizes the annual photovoltaic production is equal to the value of the latitude where the installation is located minus 10.
Although this criterion is perfect for optimizing annual generation, there may be cases in which it is not the most convenient, for example, if the user’s consumption is concentrated in certain months of the year. With a high tilt angle there is a tendency to reduce the incident radiation during the spring or summer months and to increase it in the autumn and winter months, the opposite occurs if the tilt angle is low.
Orientation
The best orientation for any building is usually south, because of the use of light and heat. The same happens with solar panels, if the orientation deviates from the south, losses are produced, which tend to increase the greater the inclination of the panel itself.
Although globally a panel deviated from the South has less generation, its impact compared to the tilt is much less. If a panel is oriented to the east, generation will be concentrated in the first hours of the day and in the last hours if it is oriented to the west, although the losses are the same for a given deviation.
Shadows
This is the most difficult factor to assess, as the methods for calculating its impact are quite complex, so professional applications are usually used. It should be noted that its effects on the installation vary greatly depending on the technology used.
In a conventional installation, when a panel is in shadow, not only is its production reduced, but also that of all the panels connected in series to it. This does not happen if power optimizers or microinverters are used, as each panel operates independently from the rest.