It is often believed that the TMY2/3 databases provide 30 years of real data. This is not true.
The definition of "TMY - Typical Meteorological Year
" (or "DRY - Design reference Year
") is a one-year
data construction, which gathers pieces of measurements (2-4 weeks) picked up from usually 30 years of real measurements, in order to construct a representative year for systems sizing or building thermal behaviour analysis. This construction obeys precise rules, and aims to provide an average year, but including some extreme values.
The TMY3 are constructed using more recent data than the TMY2 (1991-2005 against 1961-1990 respectively).
Please refer to the NREL site
for TMY3 data.
Now if you can get some real years of recent measurements (for example from SolarAnywhere of NREL), you can do the simulation for each available year, and then average the results (on a monthly