The electric energy which is being produced by photovoltaic panels in these systems is stored in batteries and the user fulfils the energy need (night and day) from these batteries. The capacity of the system may be sized in order to meet the user’s need throughout autonomy period (period when the electricity cannot be produced by sun). The production of both hot water and electricity is provided via these panels at the same time. At least 25% extra electricity production is provided with the cooled PV cells annually.