Solar-enabled green base stations: Cost versus utility

Solar-enabled cellular base stations are getting significant attention because they avoid greenhouse gas emission as well as easily available. Dimensioning of base station is a very important issue where the photo-voltaic (PV) panel size and storage capacity are determined to operate the system for a long time with minimum energy black out. In this work we look into energy outage aware system cost as well as utility of solar-enabled base stations. Hourly harvested energy and traffic dependent hourly consumed energy are considered for analysis. First, the quantized profile of harvested and consumed energy are obtained. Subsequently, the lower bound on PV panel and storage capacity is determined which provides dimensioning information a priori and at reduced complexity. To calculate the outage probability, a discrete-time Markov chain is formed with different energy levels of the battery as the system states. The state transition probabilities depend on the harvested and consumed energy profile. It is observed that, with more stringent outage constraint, the harvested energy which is neither utilized nor stored increases significantly. To this end, we suggest the system other than cost optimal where the excess energy is sold to the intelligent smart power grid to generate revenue. Harvested and consumed energies of the three cities situated at different geographical locations are considered to verify the results.