In this study, it is proposed a deep neural network approach, which has the capability to extract superior features on complex and nonlinear time series data, for forecasting global solar irradiance more accurately. This approach has also been used to expose both the relationship between input data and output data, as well as the contribution of input data to the output data. Figure A. The box plot of solar irradiance (a) Year (b) Quarter. Purpose: In this study, it is aimed to develop an accurate and effective prediction model using the LSTM neural network due to a rapidly growing interest in solar power generation. It is aimed to reveal that the proposed model based on a deep learning approach outperforms compared to machine learning models and statistical models. Theory and Methods: To overcome the complexity and nonlinearity issues in time series forecasting, the LSTM neural network that is a variation of the recurrent neural network is used to predict daily global solar irradiance. The effectiveness of the suggested method is compared with the state of the art machine learning algorithms such as Decision Tree Regression, Random Forest Regression, Gradient Boosting, and K-Nearest Neighbor. Results: To evaluate the performance of the proposed model for daily global solar irradiance, it is compared by four metrics comprising MAE, RMSE, MAPE, and r2. The results have shown that the proposed LSTM model is more effective and superior according to the other benchmark models. Conclusion: In this study, it has been suggested a deep LSTM model based on deep learning for forecasting daily global solar irradiance more accurately. The presented LSTM model can extract quality features that represent sophisticated and nonlinear characteristics of time series data. Also, it has been indicated that the proposed model is a robust and useful model compared with stateof-the-art machine learning models.