HomeMy WebLinkAboutStaff Report 2506-4769CITY OF PALO ALTO
CITY COUNCIL
Monday, June 16, 2025
Council Chambers & Hybrid
5:30 PM
Agenda Item
11.Accept Electric System Reliability Key Performance Indices; CEQA – Not a Project
City Council
Staff Report
From: City Manager
Report Type: CONSENT CALENDAR
Lead Department: Utilities
Meeting Date: June 16, 2025
Report #:2506-4769
TITLE
Accept Electric System Reliability Key Performance Indices; CEQA – Not a Project
RECOMMENDATION
Staff recommends that the City Council accept Palo Alto’s electric system reliability indices and
recommended goals and reporting.
EXECUTIVE SUMMARY
As a common practice, publicly owned and investor-owned utilities track electric system
reliability through indices that track the average frequency, duration, and restoration time of
unplanned power outages. These indices include System Average Interruption Duration Index
(SAIDI), System average Interruption Frequency Index (SAIFI), and Customer Average Interruption
Duration Index (CAIDI). Since these indices are standardized across the utility sector, they provide
a good measure of system performance and the ability to compare performance between various
utility systems. Palo Alto’s electric system reliability shows improvement over time and compares
favorably to other utilities within the region and nationally. These metrics are reported quarterly
to the Utilities Advisory Commission (UAC); staff recommend prospectively to continue this
practice and, forward this reporting to the City Council with the addition of at least annual
comparisons of Palo Alto’s performance to adjacent systems (PG&E) and nationally to the City
Council as an information item. This additional reporting will ensure heightened awareness of
these metrics as the City continues to work to achieve its reliability and electrifications goals.
BACKGROUND
On a quarterly basis, City staff present outage indices to the Utility Advisory Commission. As an
industry standard, power outages and overall system reliability are tracked through standardized
indices that track average system performance over a defined period, typically 12 months. Three
indices are used to track the average duration of outages (SAIDI), average frequency of outages
(SAIFI), and the average restoration times for customers experiencing outages (CAIDI).
Presentation of this data provides the UAC and City Council with an ongoing indication of system
performance and the impact of newly implemented operating procedures, replacement of legacy
equipment, and the implementation of modern utility equipment.
•SAIDI (System Average Interruption Duration Index): This measures the average duration
of a power outage for the average customer within a given period (usually a year). A lower
SAIDI means customers experience less time without power, indicating better overall
reliability.
•SAIFI (System Average Interruption Frequency Index): This measures how often the
average customer should expect to experience a power outage over a given period
(typically 12-months). A lower SAIFI means customers experience fewer power outages,
indicating better service reliability.
•CAIDI (Customer Average Interruption Duration Index): This measures the average time
it takes to restore service to customers who have experienced an outage. A lower CAIDI
generally means utilities are able to restore power more quickly when outages do occur,
reflecting efficient outage response and quick restoration times.
ANALYSIS
Major Event Days Included Major Event Days Excluded
FY SAIDI SAIFI CAIDI SAIDI SAIFI CAIDI
2019 114.7 0.935 122.7 44.4 0.330 134.6
2020 63.9 0.486 131.4 26.2 0.248 105.6
2021 70.6 0.720 98.1 14.7 0.053 279.9
2022 7.2 0.159 45.4 1.2 0.009 132.8
2023 148.9 1.378 108.0 26.1 0.164 159.6
2024 141.4 0.691 204.5 66.8 0.385 173.5
2025*82.8 0.630 131.4 38.4 0.252 152.5
*FY2025 numbers are preliminary and represent outages through the first three quarters of the current fiscal year.
Final numbers will be updated after the FY ends and all outage data can be reviewed for accuracy.
Two sets of numbers are presented for the current and past fiscal years. One set represents all
primary level outages (excludes single transformer and single customer outages), and a second
set of data removes Major Event Days (MED) from the data to remove the influence of significant
weather events or other large outages that do not represent normal day-to-day operations. By
identifying and removing MEDs from the outage indices, year over year trends can be established
to better indicate if system performance is improving or declining. For the data presented, MED
are defined as 24-hour periods with more than 10 percent of Palo Alto’s electric customers
impacted by power outages.
Tracking the City’s year-to-year reliability indices is a good measure of internal progress toward
improved reliability but does not provide an indicator of industry-wide (national) or regional
system reliability. The charts further below present PG&E’s outages indices for the DeAnza
Division and American Public Power Association’s (APPA) tracking of nationwide system
reliability. PG&E’s DeAnza Division, which covers the cities and surrounding areas of Cupertino,
Los Altos, Los Gatos, and Mountain View, represents our local region’s electric system reliability
and the impacts of local weather events. APPA’s collection of nationwide system reliability is
narrowed to show the cutoff for the best performing systems (top 25 percent) in the United
States. Combined, these two comparisons provide additional relevance to Palo Alto’s efforts to
provide safe and highly reliable electric service. At the time of writing this staff report, 2024 data
was not available for both PG&E’s and APPA’s system reliability numbers.
PG&E DeAnza DISTRICT w/ MED PG&E DeAnza DISTRICT w/o MED
Calendar Year SAIDI SAIFI CAIDI SAIDI SAIFI CAIDI
2019 612.7 1.601 382.7 91.3 0.873 104.6
2020 249.6 1.433 174.1 83.1 0.711 117
2021 163.6 1.43 114.4 121 0.787 153.8
2022 207.3 1.689 122.7 120.4 1.001 120.3
2023 459.8 2.161 212.8 173.3 1.002 173
National Indices With MED National Indices Without MED
Calendar Year SAIDI SAIFI CAIDI SAIDI SAIFI CAIDI
2019 Top Quartile POU 85.0 0.890 86.9 55.8 0.660 72.4
2020 Top Quartile POU 86.2 0.800 91.3 56.2 0.630 73.4
2021 Top Quartile POU 84.8 0.853 86.2 53.1 0.632 74.3
2022 Top Quartile POU 79.8 0.849 83.4 54.6 0.640 73.5
2023 Top Quartile POU 80.9 0.818 90.6 51.6 0.600 75.4
Five Year Average 83.3 0.842 87.7 82.9 0.632 73.8
In comparison of both regional and national outage reliability indices, staff is recommending Palo
Alto set a goal of remaining within the five-year average of APPA’s top quartile for all three indices
(SAIDI, SAIFI, and CAIDI) when excluding MED. Staff is further recommending that Palo Alto, at all
times, outperform PG&E’s system reliability numbers for the DeAnza Division. Setting these
targets will allow comparisons on a national level, regardless of weather events, and on a regional
level including and excluding the impacts of localized weather events.
Future quarterly and annual presentations of outages indices will include these comparisons as
the comparisons aid the UAC, City Council, and utility staff in identifying trends in system
reliability.
FISCAL/RESOURCE IMPACT
This item contains no fiscal or resource impact. Future discussions may involve presentations of
operating procedures, staffing, and recommended capital replacement projects intended to
improve system performance.
STAKEHOLDER ENGAGEMENT
No stakeholder engagement was sought on this item as the data collected is internal to City
departments and comparison data is available publicly.
ENVIRONMENTAL REVIEW
City Council action on this item is not a project as defined by CEQA because the City Council
discussion of system reliability and goals is an administrative activity. CEQA Guidelines section
15378 (b)(2).
ATTACHMENTS
None.
APPROVED BY:
Alan Kurotori, Director of Utilities