Quack Economics: What the Duck Curve Actually Prices in 2026

The shape CAISO warned about in 2013 is no longer a warning; it’s the market’s operating system.

The Duck Has a Day-Ahead Market Now

On May 1, 2026, the duck curve migrated to a new pond: in the day-ahead LMPs of a regionalized Western market.

CAISO’s Extended Day-Ahead Market (EDAM) went live with PacifiCorp as its inaugural participant, and the very first clearing prices traced the shape that has defined California’s grid for over a decade, but this time, across multiple balancing authority areas simultaneously. At SP15, the day-ahead price troughed at -$10.88/MWh during hour ending 10. At PacifiCorp East (PACE), the same hour cleared at +$2.57/MWh, a $13.45/MWh spread that is the duck curve expressed not as a load shape, but as price geography. By hour ending 19, all five Western hubs converged to within $0.25/MWh of each other before CAISO pulled away to $30+/MWh at 8pm as solar dropped off and PacifiCorp could not follow the evening ramp.

Thirteen years after CAISO coined the term, the duck is no longer a cautionary chart in a stakeholder presentation. It is the intraday price regime of the largest power market in the Western United States, and increasingly, the structural backbone of investment, dispatch, and market design across the region.

The Shape, Briefly

For readers arriving fresh: the duck curve describes the pattern created when abundant midday solar generation suppresses net load (the electricity demand remaining after subtracting renewable output), creating a deep midday trough followed by a steep evening ramp as solar drops off and demand peaks. The visual resemblance to a duck’s silhouette gave it its name.

CAISO first published the chart in 2013 as a forward-looking concern. The concern has since become a structural fact. SP15 recorded approximately 1,180 hours of negative prices in 2024, roughly 13% of all hours in the year, up from around 530 hours in 2023. The median negative price deepened from approximately -$10/MWh to -$17/MWh over the same period. CAISO has curtailed in excess of two million MWh of utility-scale wind and solar annually in recent years, and the net load valley has sunk more than 13.6 GW below where it sat in 2018. Average spring days now see net load swings exceeding 24 GW in eight hours.

The duck, in other words, has become a giraffe. A fiery debate over the precise taxonomy of the curve can be had on trading floors across North America. But what matters for capital allocation is not the metaphor; it’s the price formation regime the shape has created.

The Duck Curve as Price Regime

The EDAM launch day data crystallizes something that market participants have been pricing around for years: the duck curve is not a grid operations curiosity. It is the dominant driver of when and where value accrues in the Western energy stack.

Consider the divergence. At the solar-saturated trough, SP15 was printing double-digit negative prices while NP15, in the same ISO, never went negative at all, bottoming at $3.74/MWh between 1-2pm. PacifiCorp West (PACW) barely dipped below zero. The spread between California’s deepest solar oversupply and neighboring balancing areas is now a tradable, forecastable price signal, one that EDAM has made transparent for the first time in a centralized day-ahead framework. The wider footprint mitigates the belly, but it does not eliminate it. Even with ~170 GW of capacity committed to EDAM, California’s solar surplus remains too deep to export away entirely.

The evening ramp tells the other half of the story. The convergence of all five hubs at 7pm, within a quarter-dollar of each other, before CAISO pulled sharply higher at 8pm, reveals that the ramp is not just a dispatch event. It is a pricing event, a brief window where the entire Western stack competes for the same megawatts, and where forecast error concentrates. CAISO’s concurrent Day-Ahead Market Enhancements (DAME) now price that forecast uncertainty directly through Imbalance Reserves, meaning the ramp premium is no longer hidden in out-of-market operator interventions but baked into the cleared day-ahead price.

Plucking the Value Stack

The duck curve’s maturation into a persistent price regime has specific, measurable consequences for the assets exposed to it.

Storage is the most obvious beneficiary, and the most exposed to its own success. CAISO’s battery capacity has surged from roughly 500 MW in 2020 to over 13 GW by early 2025, and nearly 40% of new solar applications in 2024–2025 now include co-located batteries. The arbitrage thesis is straightforward: charge at negative midday prices, discharge into the evening ramp. But as storage saturates the ramp window, it compresses the very spread it monetizes. The equilibrium between storage deployment and ramp premium is the defining question for battery economics in CAISO through the late 2020s.

Resource adequacy valuation is the less visible but arguably more consequential repricing. CAISO’s ongoing shift from effective load carrying capability (ELCC) to an exceedance-based “slice of day” framework is a direct institutional response to the duck curve. Solar’s RA contribution has been structurally derated; ELCC values now sit at roughly 8–11% of nameplate, because the hours when solar produces the most are the hours when the system needs it least. This reprices the entire RA complex, and it is one of the forces behind the whipsaw in Cal 25 and Cal 26 system RA pricing that defined 2024. Meanwhile, the CAISO interconnection queue has shrunk to approximately 22 GW of active solar and less than 1 GW of wind, suggesting the supply that created the duck is maturing, not accelerating.

Sitting Duck or Moving Target?

Can storage and regional market expansion flatten the duck before the duck permanently reshapes Western market design?

Base case: The duck persists through the late 2020s. Solar additions continue to outpace storage deployment and regional transmission buildout. EDAM mitigates but does not eliminate midday oversupply; California’s solar surplus is simply too deep relative to the absorptive capacity of adjacent balancing areas. Evening ramp premiums remain structurally elevated, supporting storage and peaker economics. The two-market Western structure, with EDAM live now and Markets+ launching October 2027, propagates the duck curve’s price signals across different footprints, potentially creating new seam dynamics at the boundary.

High case (deeper duck): Accelerated solar buildout following permitting normalization deepens the belly further, pushing midday prices deeply negative for more hours across more months. Storage economics improve in the near term, but saturation risk grows as more batteries compete for the same ramp window. RA repricing accelerates as solar’s exceedance-based contribution shrinks further. Curtailment exceeds three million MWh annually.

Low case (flattening duck): Aggressive storage deployment, EDAM expansion to additional BAAs (Portland General Electric in October 2026, PNM, BANC, LADWP, and Turlock committed for 2027), and, critically, data center load growth that adds flat 24/7 baseload demand in California partially fill the belly. If hyperscaler demand materializes at scale in CAISO, it is the most plausible organic demand-side flattener of the duck. Midday energy reprices upward; the ramp premium compresses.

Bottom Line

The duck curve is no longer a diagram. It is the operating system of Western power pricing, the shape that determines when energy has value, when it doesn’t, where storage revenue concentrates, how RA is accredited, and why EDAM exists at all. Every major market design evolution in the West over the past five years (EDAM, DAME, Imbalance Reserves, slice-of-day RA, the two-market structure) is, at some level, a response to this single load shape. Investors, developers, and traders who still treat the duck curve as a grid operations footnote are underestimating the degree to which it now drives capital allocation, asset valuation, and forward price formation across the region. The duck grew up. The market is still catching on.