The difference in annual averages calculated from time series or TMY (climData) and iMaps/pvPlanner can be as high as ±1%. In special cases, higher differences have been observed between data from the older version of the database (iMaps/pvPlanner) and the data computed by the recent model (climData). This is due to the fact that iMaps/pvPlanner works with a precalculated database we are updating every 1-2 years, while climData always use the latest model and period of data available.
Regarding the expected uncertainty, our recommendation for most of the cases is directly adding ±1% more to the model's uncertainty factor in order to cover such deviations. For example, for areas where climData's model uncertainty is ±4%, it is advisable to raise it up to ±5% when working with iMaps/pvPlanner values.
New releases are announced in the section Release notes.