In this paper, we study how to use the solar radiation model to predict energy arrivals and to allocate energy resource at an energy harvesting base station (BS). First, some primary knowledge about solar radiation is reviewed and summarized. We present two solar energy models for cloudless days and cloudy days, respectively. Then artificial neural network (ANN) is used to predict solar energy arrivals in a short period, which has an improved performance compared with the previous linear model. In the end, the allocation of received energy is considered, and one optimal offline algorithm and four heuristics online algorithms are proposed. We evaluate the performance of the algorithms using Denver’s solar radiation data in recent 27 years from National Renewable Energy Laboratory (NERL). Simulation results show our prediction and optimization algorithm achieves nearly optimal performance.