“…Therefore, it can be concluded that both UC and M3 have improved the short-term GHI forecasting accuracy significantly. 3) Calendar and weather effects: It is reported in the literature that the forecasting accuracy of power time series, such as solar and load, is influenced by calendar effects [37] and weather effects [8]. To further explore the calendar and weather effects on the developed method, the best model(s) in each group is(are) picked out to make comparisons, which are C opt , SVR 3 , and GBM 3 in the UC-M3 group ({C opt,cm , SVR 3,cm , GBM 3,cm }∈M l,cm ), C opt and SVR 2 in the UC-SAML group ({C opt,cs , SVR 2,cs }∈M l,cs ), SVR 2 in the AIO-M3 group (SVR 2,am ∈M l,am ), and 1HA persistence of cloudiness method in the AIO-SAML group (P as ∈M l,as ).…”