1. Solar Eclipse Overview August 2017
Portland Control Center
Jack Geiger

2. System Overview - PacifiCorp
Two Balancing Areas
PACW (WA, OR, CA)
~4000MW Peak Load (expected)
~2500MW of Thermal Generation
~65MW of Solar Generation
~650MW Wind Generation
PACE (UT, ID, WY)
~9,000MW Peak Load (expected)
~8,700MW of Thermal Generation
~850MW of Solar Generation
~1450MW of Wind Generation

3. Solar Overview – and impacts
PACW will contain ~65MW at the time of the Eclipse
No System Impact expected.
PACE will contain ~1000MW at the time of the Eclipse
90% of this generation is located in Southern Utah (far outside of the path of Totality).
There are currently no educated estimates with regard to “behind the meter solar”
PAC has coordinated with CAISO and expects to lose ~60% of its Solar Capacity for the duration of the eclipse (anticipated to run from ~9:30 – 11:30 PT)
Total loss is expected to be ~600MW – over approximately 30 minutes (20MW/Min)
This will occur at the end of the “morning ramp” for PACE.
PacifiCorp is not anticipating a significant decrease in Load. 3

4. Mitigation Plan PACW is not expecting an System Impact.
PACE will plan to base load thermal generation to the extent possible and maintain MW of additional reserves. In addition, PACE has approximately 500MW of interruptible load that may be called upon if the situation demands.
As this will occur in August – PacifiCorp is not expected a significant number of Transmission or Generation Outages to contribute to this event --- however, no Planned Outage that will result in the decrease of available non-solar generation capacity will be scheduled that day.
After initial Planning Assessments and Studies – there have been no identified Reliability Impacts.
Should an unplanned or forced outage result in a significant impact to available Reserve Generation or its ability to meet downward system Ramp, PAC has internally discussed and is ready to implement Outages on Solar Facilities in PACE until the afternoon. 4

5. Energy Imbalance Market
As a member of the Energy Imbalance Market – PacifiCorp must provide a planned schedule for all participating generation facilities. This includes Variable Renewables such as Wind and Solar.
PacifiCorp will work with the Third-Party-Vendor that provides the Solar Resource Forecast to verify it accurately reflects the expected loss of Solar Generation.
If executed properly, the EIM will see the loss of Solar and will redispatch PACE Generation accordingly to maintain Generation/Load Balance.
As an additional consideration – it may become necessary to limit or remove the Dynamic Transfer capabilities between BAs within the EIM – preventing undesired system or generation dispatch swings – this can be initiated very quickly with coordination with CAISO. 5