The duck curve — why more solar never fills the 6pm peak
Energy Realism
a sister site of Unprepared
70%
solar generation total demand net demand — what gas, coal, hydro or nuclear must still supply
At 1pm, solar is pouring out ~19 GW — push the slider and watch the midday belly sink toward zero (that surplus gets curtailed). But at 6:30pm, when demand peaks, solar is already ≈0: the evening gap stays at ~31.2 GW no matter how much solar you add.That residual peak is the firm capacity wind and solar can't deliver — and the cost LCOE never shows.
Representative high-solar day, NEM-scale (illustrative — the curve's shape is well documented by AEMO & CAISO; exact MW vary by day and season).