Minimum cost solar power systems for LTE macro base stations

This paper proposes an algorithm for the identification of the minimum cost solution over a 10 year time horizon to power an LTE (Long-Term Evolution) macro base station, using a photovoltaic solar panel, a set of batteries, and optionally also a secondary power source, which can be a connection to a (possibly unreliable) power grid, or a small Diesel generator. The optimization is formalised as an Mixed Integer Programming (MIP) problem, which, after linearization, can be solved with CPLEX. A heuristic algorithm is also proposed, with the objective of decreasing the computational complexity of the optimization. Numerical results show that a hybrid solar-grid (or solar-diesel) power system saves a significant fraction of the total cost, compared to a pure solar system, and to the traditional power-grid system, over the investigated 10-year period, in a south European city, like Torino in Italy, as well as in a location close to the tropic, like Aswan in Egypt. Our proposed heuristic algorithm can be used to obtain a solution within 10-20% of the optimum, at a computational speed 200 times faster than the MIP solution.