How is the solar radiation? The efficiency of a solar system, whether for the production of domestic hot water or for the generation of electricity, depends on the solar radiation available on the collection surface, i.e. on the solar collector.
Have precise information on the radiation solar it is essential not only for operators to design and size a system correctly, but also for private users in the evaluation phase to find out if the location, exposure and inclination of the plane on which the panels are foreseen are such as to allow proper operation .
Since the spread of solar systems has become massive (think of solar roofs and photovoltaic tiles), information ondaily solar radiation have become a matter of public utility. For this reason, ENEA has developed a tool for calculating the daily solar radiation of any Italian location by crossing geographic data with those collected from the weather in real time.
The ENEA tool, published in the Italian atlas of solar radiation, is based on an algorithm that calculates the radiation solar which reaches the ground starting from the cloud cover maps made by Meteosat satellites. The procedure is as follows: note the amount of sun that would reach the ground with a clear sky, the greater the cloud cover and the greater the attenuation of the radiation solar.
A crucial aspect for the usefulness of the tool is that the ENEA algorithm allows you to calculate solar radiation in terms of daily solar radiation of a non-horizontal surface oriented arbitrarily with respect to the ground. This is the usual case of the glass surfaces of buildings or solar panels and hybrid solar systems usually placed on roofs for the production of hot water.
The calculation of solar radiation is made taking into account the procedure provided by the UNI standards and in addition it allows to evaluate the effect of the presence of any obstacles that, only at certain times of the day (mountains, hills, other artifacts ...) can be interposed shielding the sun's rays. ENEA has announced that soon the instrument will be integrated also by other radiation data archives (for example historical ones) and by the possibility of making calculations also on the basis of forecasts, and not only of surveys, weather.
Calculate solar radiation with the ENEA tool