The wireless industry is preparing the fifth generation wireless systems with several requirements regarding capacity and coverage area. A promising solution to meet this challenge is a densification of the network via a large scale deployment of small cells from different sizes. The advantage here is that small cells are easy to deploy and cost-efficient compared to macro base stations. However, the challenge is to ensure a reliable backhaul links. Mesh routers backhauling is one of the candidate solutions here, since it is easy to deploy, doesn't use wired connections between locations and cost-efficient. Nevertheless, the issue is to deploy routers in the suitable locations that provide the convenient and cheaper power sources. In this paper, we address the problem of mesh routers placement to ensure small cells backhauling. We propose a novel approach that aims to minimize the number of mesh routers and optimize their placement among locations offering the possibility to use solar panels. We first model the problem as an Integer Linear Program (ILP) and since it is hard to find the optimal solution with a large number of mesh routers and small cells, we propose also an heuristic approach called GPMR (Green Placement for Mesh Routers). We study the performance of both, the ILP model and the proposed heuristic GPMR, through simulations scenarios. Results show that GPMR provided performances close to those provided by ILP when the number of small cells is less than 10.We also show that the results provided by our heuristic GPMR follow an evolution close to the one observed in the optimal solutions when the number of small cells is high (more than 20).Thus, our heuristic approach can be used to obtain a near-optimal performance for ultra-dense networks.