• Bees algorithm;
  • global solar radiation;
  • empirical coefficients;
  • statistical regression techniques;
  • empirical-based models;
  • intelligent-based models

Measurement of solar radiance demands expensive devices to be used. Alternatively, estimator models are used instead. In this article, a new method based on the empirical equations is introduced to estimate the monthly average daily global solar radiation (GSR) on a horizontal surface. The proposed method uses Bees algorithm as a heuristic and population-based search technique. The best coefficients of linear and nonlinear empirical models and GSR are calculated for seven different climate regions of Iran using proposed algorithm written in MATLAB software. The results of the proposed method are compared with other techniques. The result shows that the proposed method is more accurate in estimating the monthly average daily GSR. © 2013 American Institute of Chemical Engineers Environ Prog, 33: 1042–1050, 2014