Electric grids across the U.S. are anticipating a rapid decline in solar generation during Monday’s total solar eclipse, which will span multiple states.
NASA estimates the path of totality – when the sun is fully blocked by the moon – will last from 1:30 pm CDT (1830 GMT) to 2:35 pm CDT in the U.S.
Here’s how the eclipse will affect grid operators across the country:
The eclipse is forecast to pass Texas from 12:10 p.m. to 3:10 p.m. CDT and cause solar power generation to dip to roughly 8% of it maximum output at its peak, the Electric Reliability Council of Texas said.
ERCOT expects solar generation to drop from more than 10,000 MW to about 1300 MW over two hours, when demand will hover between 48,899 MW and 51,539 MW. Solar can account for 15% to over 20% of ERCOT’s total electricity.
ERCOT does not expect to face any grid reliability issues, but said it has analyzed challenges with ramping – essentially, the process of increasing or decreasing electricity generation to match demand — posed by the eclipse.
If it does detect reliability issues, it may decide to commit additional resources or turn to ancillary services in real time, an ERCOT spokesperson said.
Ancillary services are additional resources purchased by ERCOT a day before to balance the next day’s supply and demand.
The Midcontinent Independent System Operator, which operates the grid in all or part of 15 states in the West, Midwest and the South, would normally see 5,500 MW of solar capacity on a sunny day.
The eclipse could shrink that by 4,000 MW over 90 minutes, followed by a 3,000 MW rebound, it said. However, the grid operator doesn’t anticipate reliability issues as a result.
“Solar generation will rapidly decrease then increase, resulting in a need for ramp and may cause congestion management challenges,” MISO said in an operations report.
MISO plans to increase reserve requirements and will also line up extra generation that can come online quickly if needed, it said.
