Jason Ausmus Manager Operations Planning

1. Solar Eclipse Post-Event Observations Oct 24, 2017 Jason AusmusManager Operations Planning

2. Overview • Eclipse Path and Preparation • BA/TOP Coordination Efforts • Projected Solar Gen Reduction • Actual Solar Gen Reduction • Other Eclipse Event Observations • Post-Eclipse Analysis Efforts

3. Aug 21, 2017 (9:00A – 12:15P PDT)

4. Peak/BA Eclipse Preparation Efforts • Requested event information and Operating Plans from all BA’s in the Peak footprint (plus AESO) • Summarized into Operating Memo for footprint • Held readiness webinar on Aug 17th to present study results and expected impact • Excellent response from BAs in providing data, operating plans and webinar participation!

5. Other Preparations by Peak • Real-time Ops Engineers (ROEs) also performed studies the night before utilizing the latest inputs • Created additional displays for situational awareness purposes

6. Estimated Impacts to Peak Footprint 1Utility Scale number accounts for both Solar PV and Solar Thermal • Utility Scale PV (uPV) estimates made assuming obscuration impact was 1 to 1, i.e. for every 1% obscuration a 1% MW output reduction will occur • Distribution Scale PV (dPV) estimates came from survey results

7. Actual uPV Impact due to the Eclipse ∆ ≈ + 115 MW/min ∆ ≈ + 80 MW/min ∆ ≈ -55 MW/min

8. Actual Impacts to Peak Footprint 1Utility Scale number accounts for both Solar PV and Solar Thermal • Actual Utility Scale PV (uPV) reduction confirmed the 1 to 1 relationship between % obscuration and % MW output, i.e. for every 1% obscuration a 1% MW output reduction will occur

9. Challenge of calculating exact dPV Impact • One of the challenges going into the eclipse was knowing the exact dPV installations • Not a lot of visibility behind-the-meter (BTM) • Difficulty separating changes in system load from changes in BTM generation • Peak collaborating with the National Renewable Energy Laboratory (NREL) • One objective is to determine actual BTM impact of dPV installations of the eclipse by BA

10. Effect of Distributed PV on System Load • Comparison of load ramp before eclipse (yellow arrow) vs during eclipse (blue arrow) • Load ramp increase due to reduction of distributed PV output resulting in increase in load on system • CAISO Solar Gen • CAISO System Load Eclipse Start Eclipse Max Eclipse Start Eclipse Max

11. System Loading Observations • During the eclipse, system load decreased • Some load drop was expected • 5% load drop in March 2015 Europe Eclipse • Likely causes were attributed to drop in temperature during the eclipse, human factors (curiosity of the event), etc. • Temperature drops were observed to be anywhere from 4 – 11 degrees in a 1 hour period

12. Actual uPV Impact due to the Eclipse

13. BA Area Generation Output – Most Significant Changes *NREL's work was funded by the DOE SunShot Initiative

14. BA Area Generation Output – Most Significant Changes *NREL's work was funded by the DOE SunShot Initiative

15. Generation Output by Fuel Type *NREL's work was funded by the DOE SunShot Initiative

16. Generation Output by Fuel Type *NREL's work was funded by the DOE SunShot Initiative

17. Select Path Flow Changes *NREL's work was funded by the DOE SunShot Initiative

18. Select Path Flow Changes *NREL's work was funded by the DOE SunShot Initiative

20. Other System Event Observations • No reliability issues observed during event • Sufficient reserves were maintained for the duration of the event • Peak and NREL currently collaborating on a final report of the event

21. Apr 8th 2024 – Next Solar Eclipse for U.S.

22. Apr 8th 2024 – Next Solar Eclipse for U.S.