Hawaiian Electric Cos. (HECO) is proposing to double its hosting capacity for solar energy. The utility announced its intentions in late January to increase its penetration limits for rooftop solar minimum daytime load (MDL) from 120% to 250% of MDL. Those increases would be among the highest thresholds for solar penetration on distribution circuits in the U.S.

Inverter testing at the U.S. Department of Energy's National Renewable Energy Laboratory's (NREL's) Energy Systems Integration Facility (ESIF) looked at ways to quantify transient load rejection overvoltage (LRO). The national laboratory says LRO is one of the greatest barriers to allowing more distributed energy, like solar, on the grid.

LRO conditions can occur when a local breaker or feeder opens and the power output from a distributed energy resource surpasses the local load. Such issues in the past have limited HECO’s use of distributed generation on its feeders.

"ESIF enables NREL and DOE to leverage strong partnerships with manufacturers and utilities to help integrate renewable energy into a smarter, more resilient energy system," says NREL's Associate Laboratory Director for Energy Systems Integration, Bryan Hannegan.

Results from NREL testing helped to mitigate HECO’s LRO challenges it incurred from advanced photovoltaic inverters.

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