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NREL, SolarCity Addressing Challenges of High Penetrations of Distributed Photovoltaics

NREL is collaborating with SolarCity at the Energy Systems Integration Facility (ESIF) to address the safety, reliability, and stability challenges of interconnecting high penetrations of distributed photovoltaics (PV) with the electric power system.

"We know how important the option of solar is for our customers. Solving these issues requires that everyone—utilities, the solar industry, and other leading technical experts like NREL—work together. That's what this work is all about. With the highest amount of solar in the nation, our utilities are facing potential reliability and safety issues before anywhere else."
- Colton Ching, Vice President for Energy Delivery, Hawaiian Electric

The work includes collaborating with the Hawaiian Electric Companies to analyze high-penetration solar scenarios using advanced modeling and inverter testing at the ESIF. Results to date have been so promising that Hawaiian Electric has more than doubled the amount of rooftop solar it allows on its grid, showing utilities across the country that distributed solar is not a liability for reliability—and can even be an asset.

Project Impact

  • Waiting customers connected. Based on the results of this work, Hawaiian Electric cleared the queue of some 2,500 customers waiting to connect their PV systems to the grid.
  • Ceiling for solar power in Hawaii raised. Limits on distributed solar power were more than doubled from 120% of minimum daytime load to 250%.
  • Interconnection standards and codes changed. NREL researchers helped to update IEEE 1547 and UL 1741 to standardize inverter testing protocols and procedures for advanced inverter functionalities.