**Appendix A**

The following figures show detailed Taylor diagrams for each one of the weathers analyzed in the study to complement Figure 3. Figure A1 shows Pamplona's weather, Figure A2 Gedved's weather, and Figure A3 Lavrion's weather. For each location, six diagrams are shown, one for each weather parameter (*Temp*, *RH*, *DNI*, *DHI*, *WS*, and *WD*). The diagrams show the statistical indexes (correlation *R*, centered root-mean-squared difference *RMSdi f f* , and standard deviation *σf*) calculated on an hourly basis for annual, season, and monthly data.

**Figure A1.** Normalized Taylor diagrams of Pamplona (Spain) comparing *on-site* and *third-party* weather data, showing temperature, relative humidity, direct normal irradiation, diffuse horizontal irradiation, wind speed, and wind direction.

**Figure A2.** Normalized Taylor diagrams of Gedved (Denmark) comparing *on-site* and *third-party* weather data, showing temperature, relative humidity, direct normal irradiation, diffuse horizontal irradiation, wind speed, and wind direction.

**Figure A3.** Normalized Taylor diagrams of Lavrion (Greece) comparing *on-site* and *third-party* weather data, showing temperature, relative humidity, direct normal irradiation, diffuse horizontal irradiation, wind speed, and wind direction.
