The present disclosure describes a system and a method for generating energy from geothermal sources. The system includes an injection well and a production well extending underground, a first lateral section connected to the injection well and a second lateral section connected to the production well, the first and second lateral sections connected with a multilateral connector, and at least one sublateral branch extending from at least one of the first or the second lateral section into the rock formation, defining a pressure-tested downhole well loop fluidly isolated from the rock formation and in a heat transfer arrangement therewith. The downhole well loop cased in steel within the rock formation. The downhole well loop to receive working fluid capable of undergoing phase change between liquid and gas within the downhole well loop as a result of heat transferred from the rock formation and the at least one sublateral branch.