This document compares the costs of fueling electric vehicles using electricity versus gasoline. It shows that: 1) For drivers of high-mileage gasoline vehicles like the Toyota Prius, the cost of electricity at $0.31/kWh is equivalent to paying $5/gallon for gasoline. 2) The cost of charging electric vehicles can quickly exceed the cost of gasoline if high-powered chargers are used and site loads are not managed, even at high utilization rates. 3) Charging electric vehicles using standard 120V outlets has low costs, even with demand charges, and meets the needs of most drivers who charge before peak hours.

1. Comparing gasoline & electric ‘fuel’ price
To a plug‐in Prius driver $0.31/kWh
$/gallon equivalent electricity costs as much as $5.00
gasolinel1
$6.00
(Lower Use)
$0.31/kWh
$5.00 Drivers of high‐MPG cars are DR Tier 4
economically indifferent to
F
fuel choice at relatively low
u $4.00 electricity prices
e
l
$3.00
c
o $0.14/kWh
EV-TOU-2
s $2.00
Super Off-Peak
t (Higher Use)
$1.00
$0.00
MPG > 10 20 30 40 50
Hummer Honda Accord Toyota Prius
77% of drivers cite fuel-cost savings as the #1 benefit to owning a plug-in vehicle2
1.) Assumes 3 miles/kWh; example (50/3) x $0.31 = $5.16
2.) J.D. Power, 2012 utility customer satisfaction survey Page 6 of 21

2. Fast Charge - Highest Cost
Utility billing cost per 50-miles
On AL-TOU in Summer1
23‐minutes per car at 48 kW All other times Hours
Demand
Charges During On‐Peak
$60 24
Average $46.96 gge3
$/kWh2 Energy
$50 $2.93 Total charging hrs/day
19
$40 For a Plug‐in Prius driver, utility billing costs can
$24 quickly exceed gasoline3 if site loads are not 14
managed, even at high utilization rates.
$30
$1.52
$12.91 gge
9
$20 $12 $1.04
$0.81
$23 $8 4
$10 $6
$11
$8 $6
$0 $1.61 $1.61 $1.61 $1.61 (1)
2% utilization 3% utilization 5% utilization 6% utilization
30 60 90 120
(1 car per day) (4 cars per day)
Cars charged during 30‐day period
1.) Assumes AL-TOU rate as of May 2012; 90% charging efficiency and 3 miles/kWh
2.) Average $/kWh = (total utility bill / total kWh measured at meter during billing period) / total cars charged during billing period
3.) Assumes 48 MPG (e.g. 2012 Plug-in Prius) and 3 miles/kWh
4.) Assumes average of AL-TOU On, Semi and Off-Peak and includes UDC, Commodity, DWR Bond, Taxes (i.e., approximately ~$0.10./kWh) as of Jun 2012 Page 9 of 21

3. Level 1 - Highest Cost
Utility billing cost per 50-miles
On AL-TOU in Summer1
13.2 hours per car at 1.4 kW All other times Hours
Demand
Charges During On‐Peak
$10 24
$9 Energy
*Each Level 1 unit can provide
Total charging hrs/day
$8 one 50-mile charge each day
19
$7
Charging from standard 120V outlets is low cost
$6 even with all demand charges...and serves the 14
overwhelming majority of drivers before Noon.
$5
$2.88 gge3
$4 9
*Infeasible due to
$0.18 charge duration
$3
$0.70 $0.14 $0.12
$2 $0.67 $0.35 $0.23 $0.12 4
$0.33 $0.22 $0.18
$0.17
$1 $1.61 $1.61 $1.61 $1.61
$0 (1)
55% utilization 108% utilization
30 60 90 120
(1 car per day) (4 cars per day)
Cars charged during 30‐day period
1.) Assumes AL-TOU rate as of May 2012; 90% charging efficiency and 3 miles/kWh
2.) Average $/kWh = (total utility bill / total kWh measured at meter during billing period) / total cars charged during billing period
3.) Assumes 48 MPG (e.g. 2012 Plug-in Prius) and 3 miles/kWh
4.) Assumes average of AL-TOU On, Semi and Off-Peak and includes UDC, Commodity, DWR Bond, Taxes (i.e., approximately ~$0.10./kWh) as of Jun 2012 Page 11 of 21

4. Summary - costs per car Without demand charges, utility billing cost
AL-TOU in Summer per car doesn’t vary with speed or
utilization rate; only energy costs remain.
No Load No New On‐ No New
4 cars/day Utilization1
Management Peak Demand
CAPEX2,3
$0.81/kWh $0.46/kWh $0.10/kWh $0.14/kWh
Fast Charge 6%
$12.91 gge $7.38 gge $1.61 gge $2.32 gge
$0.16/kWh $0.13/kWh $0.10/kWh $0.03/kWh
Level 2 70%
$2.58 gge $2.08 gge $1.61 gge $0.45 gge
$0.18/kWh $0.005/kWh
Level 1 55% ‐ ‐
$2.88 gge $0.09 gge
No Load No New On‐ No New
1 car/day Utilization1
Management Peak Demand
CAPEX
$2.93/kWh $1.55/kWh $0.10/kWh $0.05/kWh
Fast Charge 2%
$46.96 gge $24.87 gge $1.61 gge $8.68 gge
$0.29/kWh $0.20/kWh $0.10/kWh $0.08/kWh
Level 2 23%
$4.63 gge $3.13 gge $1.61 gge $1.35 gge
Equipment cost can add significantly
to per‐car charging costs2,3
1.) Hours actively charging / 24
2.) CAPEX assumptions: $100,000 for DCFC, $15,000 for Level 2, $1,000 for Level 1
3.) Assumes: $0 O&M costs; 48 MPG; 3 miles/kWh;10 year book life; 5 Yr straight-line depreciation; 40% tax rate; 5% cost of capital; 90% charging efficiency; 365 Days available
per year and $26.43 per kW demand charge. Page 12 of 21

5. How far do your employees drive to work?
Daily miles driven SDG&E employee average use:
2009 National Household Travel Survey 30 LEAFs, 2 Volts, 1 Active‐E, 1
40%
conversion (16 users)
~3 kWh/session
35% Done well before “On‐Peak”
0.3 sessions/day/EVSE
Portion of daily trips
30%
The majority of people drive
25% relatively few miles each day
20%
15%
10%
Trips exceeding ½ of all-electric Nissan LEAF range
5%
0%
0 5 15 25 35 45 55 65 75 85 95 105 115 125 135 145 155 165 175 185 195
Daily miles driven
Source: U.S. DOT, Federal Highway Administration 2009 National Household Travel Survey http://nhts.ornl.gov/2009/pub/stt.pdf
Page 13 of 21

6. Matching charging equipment to charging time
Hours required to recharge, at various power levels
Re‐charging in the entire time you remain parked results in least cost
Hrs.
14 $500 20-Amp outlet
Required range
No monthly fees
80 miles
An 80 mile charge from an outlet takes 35 miles
12 longer that the entire workday.
10 miles
10
Hours parked at work
8
A 10 and 35 mile charge are finished
well before the end of the workday.
6
$10,000 Level 2
4 Possible fees
2 $50,000 DC Fast Charger
Possible fees
0
1.8 kW 6.6 kW 50 kW
Assumptions: 3 miles of range per kWh, measure at utility meter; costs are illustrative – approximations of ‘all-in’ installed cost
Note: San Diego "...average regional commute…23.7 daily miles per person...” http://www.movesandiego.org/reports.html Page 14 of 21

7. Emerging policies
• IRS definition of “De minimis”
– …so small as to make accounting for it unreasonable or impractical
• An essential element of de minimis benefits - frequency and value
– Must be occasional or unusual in frequency
• Includes such items as (precede all with word “occasional”):
– Use of photocopier
– Snacks, coffee, doughnuts, etc.
– Tickets for entertainment events; holiday gifts
– Meal money or transportation expense for working overtime
– Personal use of a business cell phone
• Carbon credits, as per Air Resources Board
– Owned by the employer
– Estimated is OK – until Nov 2015 – then measurement is required (SB 1455)
http://www.irs.gov/govt/fslg/article/0,,id=184791,00.html Page 16 of 21