The Duck Curve: Why California Wastes Solar
Here’s a paradox in the data: California builds more solar every year, yet throws away more of it too. In 2024 the state’s grid operator curtailed about 3.4 million MWh of solar and wind — more than double the 1.5 million MWh curtailed in 2020, and 93% of it was solar (EIA/CAISO). Understand why, and you understand a major reason NEM 3.0 pays so little for midday exports — and why a battery is worth so much.
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- CAISO curtailment: ~1.5M MWh (2020) → ~3.4M MWh (2024) — more than doubled; 93% was solar.
- Midday net demand has fallen ~45% since 2020 — the “belly” of the duck curve deepening.
- Midday wholesale prices now go near zero or negative; the evening ramp pushes wholesale prices sharply higher.
- Midday oversupply is a major reason NEM 3.0’s export credits are low in solar-heavy hours — and why storage is rewarded.
What is the duck curve?
Plot California’s net electricity demand — total demand minus solar and wind — across a day, and it sags in the middle and spikes in the evening. The shape looks like a duck. As rooftop and utility solar have grown, the midday belly has sunk lower (net demand down ~45% since 2020) while the early-evening neck has grown steeper as solar drops off and people come home. The grid now has too much power at noon and a scramble to ramp up at 6 p.m.
The numbers: curtailment is climbing fast
When there’s more solar than the grid can use or export, the operator curtails it — literally turns it down. That number has climbed steeply.
| Year | Curtailed (million MWh) | Note |
|---|---|---|
| 2020 | ~1.5 | utility-scale solar |
| 2023 | ~2.6 | implied by 2024’s +29% |
| 2024 | 3.4 | 93% solar; +29% vs 2023 |
Source: EIA — Solar and wind curtailments are increasing in California (CAISO data). The 2023 value is implied by the reported 29% increase into 2024.
Midday vs evening: why the hour decides the value
The duck curve isn’t abstract — it changes what a kilowatt-hour is worth by the hour. Flip between midday and evening to see why your exported solar earns little, and why a battery that shifts it into the evening is so valuable.
What your solar is worth, by hour
Toggle the time of day.
Illustrative of CAISO’s daily pattern; exact prices and export credits vary by day, season, utility and rate plan. Directional, not a rate quote.
The grid’s problem is your battery’s opportunity
People assume NEM 3.0’s low export credit is just utilities being stingy. The curtailment data shows part of the reason: at midday, solar is genuinely worth very little to the grid — there’s already too much. NEM 3.0’s export credit follows an avoided-cost methodology, and this midday oversupply is a major driver of why those values are so low. So exporting your extra solar at noon earns almost nothing. Store it in a battery and release it during the evening ramp, when power is scarce and expensive, and the same kilowatt-hour is worth several times more. That time-shift — not the panel — is where the value now lives. See do you need a battery under NEM 3.0.
What this means for an LA homeowner
Don’t size solar to export
Building a big array to sell midday power back to the grid no longer pays — the grid is drowning in noon solar. Size to your own usage and shift the rest into storage.
A battery captures the ramp
Charging at midday (cheap, curtailed power) and discharging at the 4–9 p.m. peak is the highest-value move under both NEM 3.0 and time-of-use rates. See how batteries can even earn.
The trend is structural
Curtailment has more than doubled in four years and keeps rising as more solar comes online. The economics rewarding self-consumption and storage aren’t a fad — they follow grid physics.
Frequently asked
How much solar does California waste?
In 2024, CAISO curtailed about 3.4 million MWh of wind and solar — up 29% from 2023 and more than double the ~1.5 million MWh curtailed in 2020. 93% of the 2024 total was solar. That’s enough energy to power hundreds of thousands of homes for a year (EIA/CAISO).
What is the duck curve?
It’s the shape of California’s net electricity demand across a day — total demand minus solar and wind. Abundant midday solar sinks the middle (net demand is down ~45% since 2020) while the early evening spikes as solar fades and demand peaks. The curve looks like a duck, and it keeps getting steeper.
Why does NEM 3.0 pay so little for exported solar?
Because at midday, solar is genuinely low-value to the grid — there’s already a surplus being curtailed and wholesale prices fall near zero or negative. NEM 3.0’s export credit follows an avoided-cost methodology, and this midday oversupply is a major reason those values are low, so exporting at noon earns little. The same energy stored and used in the evening is worth far more.
Does this mean solar isn’t worth it in California?
No — it means the configuration matters. Solar that you use yourself still offsets a ~33¢/kWh retail rate. What no longer pays is building a big array to export midday power. Pairing solar with a battery to shift energy into the expensive evening is what captures the value now.
How does a battery help with the duck curve?
It time-shifts your energy. A home battery charges during the midday surplus (when solar is abundant and cheap) and discharges during the 4–9 p.m. ramp (when power is scarce and expensive). That’s the highest-value use of solar under NEM 3.0 and time-of-use rates alike.
Related reading
Turn wasted midday sun into evening power
A right-sized battery captures the value the grid can’t use at noon. Get a solar-plus-storage design from a licensed local installer.
Get a free estimatePrepared by Cali Energy, July 2026. This article is for general educational purposes only and is not legal, tax, financial, engineering, or utility advice. Rates, incentives, codes, permit requirements, equipment specifications, prices, and program terms may change; figures and timelines are estimates, not guarantees. Confirm current requirements with the applicable utility, AHJ, program administrator, manufacturer, or a licensed professional. See our Content Disclaimer. Cali Energy · 19201 Parthenia St Unit E, Northridge, CA 91324 · CSLB #1032379 (B, C-10, C-39)