Small-scale curtailment of PV generation under non-firm connections

Increasing numbers of variable renewable distributed generation units and demand from flexible distributed energy resources such as electric vehicles and heat pumps pose challenges for planning and operating the low-voltage distribution grid. Non-firm connections are an alternative for the access to available end-user flexibility which becomes increasingly relevant for more efficient grid development. This study evaluates and quantifies the impact of non-firm connections for small-scale end-users on both resolving voltage problems and end-user curtailment rates. We propose to link flexible generation capacity for curtailment with the end-user’s contracted power and define an allowed base generation which they can feed into the grid. This approach incentivises self-consumption while granting the right to feed in electricity under non-constrained grid conditions. A three-phase unbalanced power flow simulation on a real distribution grid shows that curtailment levels of around one tenth of the total generated electricity effectively mitigate overvoltage problems. This study does not consider load-shifting to generation hours and load increase over time; therefore, the actual required curtailment in a case with maximum local solar generation can be estimated as lower.