Solar And Wind Increasingly Shaping CAISO Load Curves


As more solar and wind electric generating capacity is added in California, the California Independent System Operator (CAISO) is facing an increasingly different net load shape, reports the U.S. Energy Information Agency (EIA).

Net load – the total electric demand in the system minus wind and solar generation – represents the demand that CAISO must meet with other dispatchable sources, such as natural gas, hydropower and imported electricity from outside the system.

In the summer, PV generation tends to match load requirements, both of which increase at midday. However, electricity demand in non-summer months tends to have both an upward morning ramp and a higher peak in the early evening as people return home from work.

CAISO officials have projected this shift in net load and expect the trend to become more pronounced as more solar and wind capacity is added to meet the state's 33%-by-2020 renewable portfolio standard. California's changing net load patterns are expected to create a greater need for flexible, dispatchable capacity to manage operational and reliability challenges.

According to the EIA, California's legislature, public utilities commission and CAISO have initiated a number of policies and frameworks that could mitigate challenges associated with this changing net load shape. These actions include the following:

  • Increased focus on flexible resources;
  • Implementation of a storage mandate;
  • Market design enhancements for intra-hour scheduling;
  • Creation of an energy imbalance market;
  • Development of time-of-use pricing; and
  • Assessment of demand response options.

For more information on how multiple renewable energy generation and energy storage options can produce a more reliable grid, visit the Hybrid Energy Innovations event site here.

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