A system is provided for supplying voltage to electrical loads in the on board electrical system of a motor vehicle, in which system the onboard electrical system includes at least two onboard electrical system regions. The first onboard electrical system region has an electric generator, a vehicle battery, and one or more first electrical loads, and the second onboard electrical system region has a double-layer capacitor or a so-called supercap, and one or more second electrical loads. A blocking apparatus, in particular a semiconductor diode or a circuit breaker, is provided between the two onboard electrical system regions. The blocking apparatus permits current to flow from the first onboard electrical system region to the second onboard electrical system region and largely prevents current from flowing in reverse from the second onboard electrical system region to the first onboard electrical system region. The output voltage of the electrical generator is increased and the supercap is charged when a first threshold value of the electrical voltage is undershot in the second onboard electrical system region.