In this work, global solar radiation is estimated based on sunshine duration. Solar radiation measurements have been collected from the Indian Meteorological Department (Pune, India) for the period 1986–2000. 25 model forms were selected from the literature which correlates the clearness index with sunshine duration. The coefficients of models are extracted from the data. k-fold cross-validation is then employed to improve the performance of the models. Data is split into k-groups with each group containing the same amount of data. (k-1) groups are utilized for the development of models and the rest one group is utilized for the testing of models performance. The procedure is repeated k-times and those coefficients are selected which produces the least error. Models are evaluated and compared with the help of statistical errors. Further, the statistical errors were scaled and Global Performance Indicator (GPI) was evaluated. Using GPI, models were given rank in order of suitability of estimates produced. The GPI value lies between −9.4269 and 0.4695. It has been observed that the quartic model (M-04) exhibited the best performance with MBE = 0.0259, RMSE = 1.7927, MPE = 0.1495, RRMSE = 0.0352, erMAX = 0.9072, MARE = 0.0812, MAE = 1.3843, U₉₅ = 6.3100, t-stats = 0.2397 and R = 0.8597 resulting in the highest GPI amongst all the models which were proposed.

在这项工作中，根据日照持续时间估算全球太阳辐射。从印度气象局（印度浦那）收集了1986-2000年的太阳辐射测量值。从文献中选择了25种模型形式，这些模型形式将净度指数与日照时间相关联。从数据中提取模型的系数。然后采用k倍交叉验证来改善模型的性能。数据分为k组，每组包含相同数量的数据。（k-1）组用于开发模型，其余一组用于测试模型性能。将该过程重复k次，并选择产生最小误差的那些系数。在统计误差的帮助下对模型进行评估和比较。进一步，评估统计误差并评估全球绩效指标（GPI）。使用GPI，对模型进行了排序，以使其适合所产生的估计值。GPI值介于-9.4269和0.4695之间。已经观察到四次模型（M-04）在MBE = 0.0259，RMSE = 1.7927，MPE = 0.1495，RRMSE = 0.0352，erMAX = 0.9072，MARE = 0.0812，MAE = 1.3843，U时表现出最佳性能₉₅  = 6.3100，t-stats = 0.2397和R = 0.8597，在所有提出的模型中，GPI最高。