As solar capacity grows, duck curves are getting deeper in California
So much solar has been added to California’s grid that midday net demand from conventional power plants sometimes falls near zero, creating a steep “duck curve” as demand spikes again after sunset. Commenters debate how to manage this shift from demand-driven to supply-driven electricity: options include large-scale batteries, pumped hydro, demand response via dynamic pricing, and smarter use of EVs and home thermal storage. They also highlight policy and pricing challenges, such as high retail rates, income-based grid access fees, and the economics of nuclear, rooftop solar, and home battery systems.
Duck curve & grid impacts
- Net daytime demand in California can fall near zero on the “best” solar days due to utility-scale and rooftop solar plus wind.
- This doesn’t mean plants are off; nuclear and other baseload keep running, and California exports power or charges batteries when demand is low.
- Prices sometimes hit zero or negative; curtailment of solar/wind is already common.
- Thread stresses these are exceptional days, not the average, so carbon-free progress is less than the graphs might imply.
Baseload, nuclear, and renewables
- Some argue traditional “baseload” like nuclear/coal is poorly suited to a grid dominated by variable renewables and negative prices.
- Others counter that modern nuclear can ramp and still has value covering nights and evenings; extra daytime output could be used if storage/loads exist.
- Nuclear waste costs vs solar/wind waste are debated, with examples from Germany, UK, Finland cited to argue nuclear waste is extremely expensive.
Storage and technical fixes
- Batteries, pumped hydro, and gas peaker plants are recurring solutions; hydro is constrained in California by drought risk.
- CAISO battery “capacity” is discussed (GW vs GWh vs “duration”), with some confusion over terminology but agreement storage is rapidly growing.
- Ideas include CSP with thermal storage, water/thermal tanks, and using buildings as “thermal batteries” via pre-cooling or pre-heating.
Demand-side management & flexible loads
- Dynamic pricing and time-of-use (ToU) tariffs are widely proposed to shift loads to solar-rich hours.
- Industrial users and large flexible loads (AC, water heaters, EV charging) are seen as prime candidates for automated demand response.
- Pre-cooling homes, night ventilation, and exploiting building thermal mass have mixed reception; effectiveness depends heavily on insulation and mass.
Home batteries, EVs, and cost issues
- Whole-house batteries (e.g., Powerwall) are noted as far costlier per kWh than EV packs; explanations include small volumes, integration, warranties, and “market will bear it” pricing.
- DIY LiFePO₄ racks plus inverters appear much cheaper; some report going off-grid or planning large (50–100 kWh) home systems.
- Vehicle-to-home/grid (V2L/V2G) is seen as promising but raises convenience and control concerns.
Grid pricing, equity, and regulation
- California’s new income-based fixed charges are heavily criticized as a de facto tax and distortionary; some prefer fixed infrastructure charges based on actual grid cost or connection capacity, plus separate low-income subsidies.
- There is tension over whether rural customers should pay more for costly, fire-prone infrastructure versus treating electricity as a universally subsidized “common good.”
- Utilities and regulators are accused of underusing fine-grained ToU, mismanaging risk (e.g., fire), and protecting profits rather than optimizing the grid.