1. Designing PEV Infrastructure
Do PEV TOU Rates Impact PEV Charging Time
Decisions?
Gregory W. Haddow

2. SDG&E Goals
Create an excellent customer experience and support the
growth of electric transportation while ensuring the
safe, reliable & efficient integration of PEV loads with the grid
Charging Technology & Infrastructure
Widespread & convenient
Charging Pricing
Attractive to charge off-peak
Utility System Integration
Efficient & smart
Market Development
Educate & support
2

3. EV Rate Participation & Ownership are Growing
1,800
1,600 ~1,600 Total PEVs
through June '12
1,400
1,200
701 PEV Rate Customers
1,000
(Premises Metered and/or Submetered)
800
600
400
200
394 Experimental Rate Customers
(Submetered PEV usage)
0
Jan11 Mar11 May11 Jul11 Sep11 Nov11 Jan12 Mar12 May12
Total Vehicles PEV Rate customers Experimental Rate Customers

4. What Drives Charging Time Decisions?
PEV Rates & Technology Study – CPUC approved experimental PEV
rates for EV Project & Nissan deployment
• Price – Fuel Savings? AM PM
Low Super Off-peak rates
• Technology & Information –
“Set & Forget”?
On-board Leaf technology
• Convenience & Lifestyle –
Do Travel Needs Rule?
Schedule
4

5. Research Advisory Panel
• San Diego Gas & Electric
• UC Davis, Tom Turrentine, PHEV Research Center
• EPRI, Bernie Neenan, Electric Transportation Program
• University of San Diego-EPIC, Scott Anders & Nilmini Silva-Send
• UC San Diego, Professor Graff Zivin & Ben Gilbert
• CEC, Phil Misemer
• U.S. EPA, Zoltan Jung
• CCSE, Mike Ferry
• SCE, Russ Garwacki
• SMUD, Bill Boyce
• EV Project / ECOtality, Don Karner
• Coulomb Technologies, Richard Lowenthal
• Boulder Energy Group, Bill Le Blanc
• EEI, Rick Tempchin
• CPUC Staff

6. Study Objective
To examine PEV consumer charging time preferences, use of
technology, and other relevant factors in a controlled study of
CPUC-approved time-differentiated rates coincident with the
EV Project and Nissan Leaf launch in San Diego.
Working Hypotheses
• Time variant pricing and technology use will influence
consumer charging behavior
• Greater price variations will drive more charging activity to off-
peak periods
• Enabling technology will facilitate charging behavior that is
convenient and economic to the consumer

7. Study Design
Dependent Variable
Time-of-use Charging
Ratio of on-peak charging kWh to
off-peak and super off-peak
charging kWh per day
Independent Variable
Leaf Customers Randomly Assigned
to 3 Time Variant Priced Rates
Each rate differing in super off-peak to on-
peak price spread
Conditioning Variables
• Use of Enabling Technology
• Driver Profile
• Use of Charging Facilities

8. PEV Experimental Rates – Summer
40
35
30
Cents per kWh
25
20
15
10
5
0
EV-TOU Rate 2 Rate 3
On-peak Off-peak Super Off-peak
Noon to 8pm 8pm to midnight Midnight to 5am
5am to Noon

9. Separate PEV Metering
SDG&E determines House Meter
location of the separate
PEV meter (in
series), with flexibility
regarding the
PEV Meter
disconnect breaker
Garage Panel
EVSE

10. EV TOU Rate is Effective Regardless of Price
90%
82% 83%
80% 78%
70%
% of Total Consumption
60%
50%
40%
30%
20%
13%
9% 11% 10%
10% 7% 7%
0%
On-Peak Off-Peak Super Off-Peak
EPEV-L (N=110) EPEV-M (N=146) EPEV-H (N=138)
Three Experimental EV Rate Customer Groups

11. Super Off-Peak Charging at Home
is Encouraged by TOU rates
7%
• Usage: 3 experimental PEV rate
11% groups kWh usage combined
• Data: January 2011 to June 2012
• Super Off-Peak: Midnight to 5 am
• Off-Peak: 5 am to Noon &
8 pm to Midnight
82% • On-Peak: Noon to 8 pm
On-Peak Off-Peak Super Off-Peak

12. Charging Behavior Similar Across the
3 Experimental Rate Groups
Separately metered
data isolates the
charging use
Super Off-peak usage
Midnight to 5 am
indicates the use of
EVSE or PEV timers
Hour 12 = Noon
Hour 24 = Midnight

13. Slightly Less Charging on Weekends
Indicates a
routine driving &
charging
pattern, regardle
ss of day of
week

14. TOU Rates Influence PEV Charging
TOU rates encourage off-peak charging vs. a flat rate
Nashville Electric Svc, TN
• 260 residential EVSE
• Charge: $13.43 / month
• Summer: $0.0936 / kWh
• Winter: $0.0898 / kWh $
SDG&E, CA
• 539 residential EVSE
• TOU rates
• Super off-peak:
midnight to 5am
Source: INL http://avt.inl.gov/pdf/EVProj/EVProjInfrastructureQ42011.pdf
14

15. PEV Driving Maturation in ~ 6 months
“Charge Month” is
the month after initial
charge, regardless of
calendar month of
the PEV purchase
Line denotes 3
month moving
average

16. Implications
• Too soon to tell if charging patterns are stable
• Is fueling cost so low that charging will shift to off peak
and on-peak periods over time?
• It doesn’t take much pricing incentive to change
behavior – 1 to 2 pricing difference between super off-
peak and on-peak as effective as the 1 to 6 differential
• Convenience technology works – implies smart grid
technology must be simple “set and forget” in nature
• If PEV rate structures becomes more complex
(e.g., weekday-weekend, summer-
winter, tiers), simpler technologies may be less
effective
16

17. Designing PEV Infrastructure
Gregory W. Haddow
GHaddow@SempraUtilities.com
SDGE.COM/EV
EV@SDGE.COM