  Increasing electricity prices motivates the mobile network operators to find
new energy-efficient solutions for radio access networks (RANs). In this study,
we focus on a specific type of RAN where the stand-alone solar panels are used
as alternative energy sources to the electrical grid energy. First, we describe
this hybrid energy based radio access network (HEBRAN) and formulate an
optimization problem which aims to reduce the total cost of ownership of this
network. Then, we propose a framework that provides a cost-efficient algorithm
for choosing the proper size for the solar panels and batteries of a HEBRAN and
two novel switch on/off algorithms which regulate the consumption of grid
electricity during the operation of the network. In addition, we create a
reduced model of the HEBRAN optimization problem to solve it in a mixed integer
linear programming (MILP) solver. The results show that our algorithms
outperform the MILP solution and classical switch on/off methods. Moreover, our
findings show that migrating to a HEBRAN system is feasible and has
cost-benefits for mobile network operators.
