Question
I have a doubt regarding a weather data database for Turin, which I downloaded from the website of the U.S. Department of Energy. I am using SAM as part of my thesis research, to study the energy estimates of a photovoltaic sistem.
My question is about the DNI data. I expected the DNI data to be higher than the GHI data in the early and late hours of the day. However, I noticed that your SAM database gives a lower DNI than GHI for most days.
Could you please specify on what criterion you have you used for your estimate of DNI?
Answer
The data in the weather files on the
EnergyPlus Weather Data website
comes from different sources, depending on the country. For example, the
Italy files
are from a data collection described on the
