They are those that are located on the ground, whose main purpose is the production of electrical energy to deliver it to the distribution network, either in low or high voltage and thus be able to receive a regulated premium, by Royal Decree, in order to make profitable the investment made, although with some fundamental differences with respect to the ground ones, such as the greater initial investment due to the contribution of mechanisms that follow the solar orbit (solar trackers) and a greater return on investment due to the greater production of electrical energy .