Who pays for harmonic network losses caused by PV inverters?

Abstract

The even growing number of small power (household rate) PV sets and the connecting inverters should warn utility companies to make a reconsideration on the network losses. Of course the main portion of the network losses is in connection with the fundamental current flow along the network. In our former papers [1], [2] and [3] it was pointed out that the harmonic network losses caused by non-linear loads generating harmonic currents actually are paid, because the non-linear loads receive as additional fundamental power the network losses originating by their generated harmonic currents. The PV inverter is a fundamental current power generator, but as a nonlinear element it generates harmonic currents as well. The fundamental current network loss cannot be separated into parts caused by consumption and generation; therefore the utility pays for the total energy supplied by the PV installation including the network loss. And what is the situation regarding the harmonic network loss? The paper gives a theoretical overview of the problem, furthermore – based on laboratory measurements – a proper computer simulation model was developed. Using computer simulations different practical scenarios are discussed.