Dive Brief:

• The qualifying solar capacity that counts toward resource adequacy (RA) in the California ISO is declining, a trend the grid operator expects to continue as more solar energy comes online and peak use of the electric grid shifts to later in the evening.
• Officials say there are opportunities for adding energy storage at new or existing sites outside of the ISO's formal interconnection process as the grid operator considers changes to the deliverability methodology it uses to assess RA, expected to go into effect in January.
• Energy storage additions may request a deliverability transfer from an existing portion of a generation project. Changes to the proposed RA methodology will close the window for large transfers by reducing the solar study amounts, ISO officials say.

Dive Insight:

California's grid operator is considering changes to its resource adequacy methodology to reflect a peak load period that has shifted to later in the day, when solar output is reduced. Once those changes are in place, the ISO will reassess the contribution to RA of all solar sites, at lower resource adequacy levels.

With the new deliverability methodology in place, officials say generators' opportunity to simply "transfer" the higher levels of capacity to batteries or other generation that will not be affected by the transition to the new methodology will end, meaning those resources would need to go through a lengthy interconnection review.

The ISO held an informational stakeholder meeting last week to ensure generators were aware of the opportunity to transfer portions of potentially-impacted generation to a storage resource — and that opportunities would diminish after the new methodology is implemented and excess capacity is available for anyone competing in the interconnection process. ISO officials stressed that no new policies were being developed.

"We wanted to ensure people were aware of existing options, given what we expect to be some interest in expedited procurement given current activities going on at the [California Public Utilities Commission] regarding Integrated Resource Planning and procurement track in that proceeding," Neil Millar, ISO executive director of infrastructure development, said at the Oct. 10 meeting.

The growth of load serving entities, in particular community choice aggregation programs, has regulators moving quickly to ensure the grid stays reliable while meeting environmental mandates. The state's investor-owned utilities have also indicated they are "generally supportive" of a proposed statewide procurement process for renewable resources, and a procurement track including a centralized buyer.

Grid officials at last week's meeting explained that adding resources such as storage that do not exceed output from a site "may qualify as additions that are not material modifications, and can proceed outside of the ISO interconnection process. ... New projects, or additions that increase the output from a site, must apply through the ISO interconnection process."

The ISO offers two modification review processes for projects that are online or in the interconnection queue: a Material Modification Assessment for projects that have yet to come online, and a modification review process for projects already online.

The modification review process takes about 45 days, say officials, but that clock does not start until complete, deficiency-free technical data has been submitted.