TEN years ago researchers in California began forecasting the state’s demand for electricity over the course of a day. The distinctive undulations in the data gave it a shape that caused it to be nicknamed the “duck curve”. The figures suggested that the power grid was due to face unprecedented strain. As more solar power was generated during the sunny middle of the day, the net load on the network decreased, creating the duck’s belly. As a result, that meant that the ramp-up to peak demand in the evening—the duck’s neck and beak—would be unusually steep, putting enormous pressure on a grid that was not designed for such variation. 

Power providers have two main choices to respond to the disruption caused by the mass adoption of solar-generated electricity. One option is to adapt to a more curvaceous duck, by investing in fast-ramping power plants to help the grid withstand sharp variations in its load. The other is to put the duck on a diet, by adjusting electricity pricing with hourly rates to encourage customers to shift their power usage from high-demand to low-demand times, smoothing out unwanted fluctuations.

The best solution is to do a bit of both, largely with the aid of technology. On the supply side, one trick is to calculate ever-more-precise forecasts of solar output and electricity demand at every hour of every day, to match them better. Investments in hydro and battery storage let producers stockpile energy produced during the day and distribute it in the evening. As for demand, electric vehicles may eventually be programmed to take their power when the load on the grid is relatively low. Combined with greater use of dynamic pricing, the duck curve could come to resemble a gliding seabird rather than a waddling waterfowl.