A device for improving energy efficiency in an electrical installation, comprising: - at least one inlet adapted for receiving a power grid supply voltage U, - at least one voltage U regulating element, and - at least one load voltage U Z supply outlet for feeding at least one electric load of the electrical installation, wherein the at least one regulating element is configured for changing the voltage U value according to the optimal active power consumption value of the at least one electric load, obtaining a regulated load voltage U Z corresponding to the voltage level that optimizes active power consumption of the at least one electric load, said regulated load voltage U Z being comprised in a limit voltage range corresponding to the range of operating voltage values of said at least one electric load, wherein the voltage U regulating element comprises modifying means and selection means for modifying and selecting the supply voltage U, wherein said selection means are adapted for: - shunting a voltage U D, corresponding to a decimal D of the regulated load voltage U Z, U D = D ⋅ U Z, D E [0,1], and the modifying means are adapted for: - changing the voltage U D value according to a factor R depending on the optimal active power consumption value of the at least one electric load, obtaining a modified voltage U', wherein: U ′ = R ⋅ U D, wherein the regulating element is further configured to obtain the regulated load voltage U Z being: U Z = U ∓ U ′ and wherein the voltage U regulating element further comprises processing means adapted for: - determining the voltage that optimizes active power consumption of the at least one electric load, - determining an evaluation of a variation in consumed active power P with respect to the regulated load voltage Uz, and - acting on the modifying means and selection means and wherein the modifying means are configured for changing the voltage U D value according to the evaluation such that: - if the power P increases with respect to the regulated load voltage U Z, the regulated load voltage U Z value is decreased by the modifying means, or - if the power P decreases with respect to the regulated load voltage U Z, the regulated load voltage U Z value is increased by the modifying means. - at least one inlet adapted for receiving a power grid supply voltage U, - at least one voltage U regulating element, and - at least one load voltage U Z supply outlet for feeding at least one electric load of the electrical installation, - shunting a voltage U D, corresponding to a decimal D of the regulated load voltage U Z, U D = D ⋅ U Z, D E [0,1], and the modifying means are adapted for: - changing the voltage U D value according to a factor R depending on the optimal active power consumption value of the at least one electric load, obtaining a modified voltage U', wherein: U ′ = R ⋅ U D, wherein the regulating element is further configured to obtain the regulated load voltage U Z being: U Z = U ∓ U ′ and wherein the voltage U regulating element further comprises processing means adapted for: - determining the voltage that optimizes active power consumption of the at least one electric load, - determining an evaluation of a variation in consumed active power P with respect to the regulated load voltage Uz, and - acting on the modifying means and selection means and wherein the modifying means are configured for changing the voltage U D value according to the evaluation such that: - if the power P increases with respect to the regulated load voltage U Z, the regulated load voltage U Z value is decreased by the modifying means, or - if the power P decreases with respect to the regulated load voltage U Z, the regulated load voltage U Z value is increased by the modifying means.