Sunny with a Chance of Curtailment: Operating the US Grid with Very High Levels of Solar Photovoltaics

Wesley Cole, Bethany Frew, Nina Vincent, Paul Denholm, Allister Frazier, Robert Margolis

Research output: Contribution to journalArticlepeer-review

32 Scopus Citations


With rapid declines in solar photovoltaic (PV) and energy storage costs, futures with PV penetrations approaching or exceeding 50% of total annual US generation are becoming conceivable. The operational merits of such a national-scale system have not been evaluated sufficiently. Here, we analyze in detail the operational impacts of a future US power system with very high annual levels of PV (>50%) with storage. We show that load and operating reserve requirements can be met for all hours while considering key generator operational constraints. Storage plays an active role in maintaining the balance of supply and demand during sunset hours. Under the highest PV penetration scenario, hours with >90% PV penetration are relatively common, which require rapid transitions between predominately conventional synchronous generation and mostly inverter-based generation. We observe hours with almost 400 GW (over 40%) of economic curtailment and frequent (up to 36%) hours with very low energy prices.

Original languageAmerican English
Pages (from-to)436-447
Number of pages12
StatePublished - 22 Nov 2019

Bibliographical note

Publisher Copyright:
© 2019 The Author(s)

NREL Publication Number

  • NREL/JA-6A20-71948


  • curtailment
  • energy prices
  • energy storage
  • net load
  • photovoltaic generation
  • production cost modeling
  • ramping
  • renewables
  • solar energy
  • thermal cycling


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