We forecast hourly solar irradiance time series using a novel hybrid model based on SOM (self-organizing maps), SVR (support vector regression) and PSO (particle swarm optimization). In order to solve the noise and stationarity problems in the statistical time series forecasting modelling process, SOM is applied to partition the whole input space into several disjointed regions with different characteristic information on the correlation between the input and the output. Then SVR is used to model each disjointed regions to identify the characteristic correlation. In order to reduce the performance volatility of SVM (support vector machine) with different parameters, PSO is implemented to automatically perform the parameter selection in SVR modelling. This hybrid model has been used to forecast hourly solar irradiance in Colorado, USA and Singapore. The technique is found to outperform traditional forecasting models. (C) 2015 Elsevier Ltd. All rights reserved.