Highlights
ERCOT solar may top 20 GW in 2023
Forwards weaker in 2024-25
Dispatchable, flexible margins mulled
Solar power’s reliability contribution to the Electric Reliability Council of Texas may be nearly exhausted if solar capacity reaches 20 GW by 2023, a consultant told stakeholders Aug. 29, which would necessitate increased dispatchable and flexible resources to meet increasing ramping needs.
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Electrical engineers define effective load-carrying capability as the amount a system’s loads can increase when a generator is added while maintaining the same reliability index, typically the loss-of-load expectation. Perfect ELCC would be 100% of a generator’s nameplate capacity, but that is nearly impossible, even for conventional generation.
In a presentation to ERCOT’s Supply Analysis Working Group, Astrape Consulting owner Kevin Carden said solar penetration on the ERCOT grid results in the following variations in that solar capacity’s ELCC:
- 1 GW: 78%
- 10 GW: 51%
- 20 GW: 20%
- 25 GW: 5%
As of the end of July, ERCOT had a cumulative total of 8.7 GW of solar capacity installed and approved for commercial operation and another 3.7 GW that is synchronized, meaning it feeds energy into the grid but is not approved for commercial operation.
Another 2.4 GW has signed interconnection agreements and financial security posted so it could be added in 2022, and another 10.8 GW has signed IAs and financial security posted so that it could be added by the end of 2023.
Weaker forwards seen
Forward traders may foresee less risk, however, as 2023 currently has the highest average annual on-peak forward price at the ERCOT North Hub, $91.65/MWh, in the mid-term future, dropping to about $67/MWh in 2024 and about $59/MWh in 2025.
ERCOT’s May Capacity, Demand and Reserves Report assumed solar capacity to have a summer ELCC of 81%, compared with ELCCs for wind ranging from 20% for turbines away from high-wind areas to 57% for coastal wind areas.
As the study indicates a “steady, persistent decline in the solar ELCC as we get to the penetration levels that we’re expecting to see in the near future,” Carden said, “we do think that will be a material finding.”
Walter Reid, an Advanced Power Alliance technical and regulatory consultant, pointed out that the Astrape study’s results look upon solar as “a silo” of one particular resource, when solar additions are increasingly being linked to battery storage or large flexible loads, which could mitigate the decrease in ELCC as solar capacity grows.
“That’s certainly correct,” Carden said, adding that his organization plans to complete by Sept. 9 a draft result of the ELCC study, which is also combined with a reliability study regarding the deliverability of resources to the six load zones across the ERCOT grid, with final results to be released by the end …….