Monday, August 27, 2012

Sixteen Months in Our Nissan LEAF

Through July of 2012 we have completed sixteen months of happy driving in our LEAF, with total miles traveled of 14,870.  July was one of our shortest driving distance months, with only 770 miles driven and only 26.6 average (mean) miles driven per driving day and a median of 26 miles driven per driving day.  These low driving distances were due only to our choosing to stay close to home during July, to our having no need to drive any long distance in the car, and had nothing to do with the usefulness of the car, which has stayed the same for us throughout the sixteen months of driving.

Our LEAF continues to be completely reliable, having never needed to return to the dealership for a repair of any kind in about 15,000 miles of driving.  Our driving costs have remained very low due to our ability to drive partly on solar energy generated by our home's solar power system and because of our utility's Time of Use rates for EV charging combined with that solar power. Our fuel costs continue to be zero, as they have for the life of the car.

I had occasion to gas up our Toyota Prius hybrid the other day, my wife being the one who usually drives it and fuels it, and it was rather an unfamiliar feeling to drive into a gas station.  One tends to forget that that unpleasant little piece of daily life can be so easily forgotten.  I don't miss the gas station at all.



The car continues to be as silent, powerful and zippy to drive around town as it was when it was new, and I enjoy the open and airy interior and the attractive blue paint job whenever I drive it.  The flexible interior continues to be very useful for our family of four, fitting four adults and a child car seat when necessary, and able to carry cargo of some bulk with the rear seats folded.

Driving range remains in the area of 75 miles if we drive at a dashboard-indicated economy of 4 mi/kWh, which is easy to achieve. This range capability reflects a reduction of 13% as compared with the car when it was new, measured by a careful driving range test conducted in July.  For our driving needs, this capacity reduction due to battery aging hasn't yet become a problem because the range capability remains within our usual driving range needs.

Electric Bill
With summer rates in effect we are enjoying maximum solar power generation from our home's rooftop solar "power plant".  We are seeing the expected electric bill benefits of credit balances rather than actual bills.  For our July/August bill, our bill is a credit of $58.30.  Added to our previous credit balance of $14.53, we now have a total cumulative balance of  -$72.83 for the net metering year to date after month #5.  We expect this credit balance to grow for the two remaining months of the summer, which will contribute to a very low actual cumulative bill due at the end of next February of close to zero for all of our electrical use for the year.

On August 13, SCE installed a Smart Meter, replacing our previous digital interval recording meter.  The change has been pretty much a non-event for us so far.  The new meter, like our previous one, displays the cumulative energy used by our household from our utility on one register ("register 1") and the energy sent back to the utility on a second register ("register 71").  I use these readings, along with the power usage readings from our TED energy monitoring system and the readings from our solar PV system's power inverter, to track our energy usage and generation.

I haven't seen the data on SCE's (our utility's) web site as yet, but I've been told to expect to be able to see our power usage per hour for each day as recent as the previous day.  Perhaps SCE needs a few weeks to get that display functioning on their web site for new Smart Metering customers.


The Numbers:
2011 Nissan LEAF SL Placed in Service: March 30, 2011
All Home Charging Done Using: 240 Volt Aerovironment/Nissan Level 2 EVSE
Home Solar PV System: 24 Sunpower 215W panels totaling 5.16 kW DC mounted on a 20 degree South facing roof.
Total Solar PV Power Generated for Net Metering Year Ended February 2012:  8,568 kWh
Our LEAF's Longest Range Full Charge to Empty ("Turtle"): 86.5 miles (at 4.0 mi/kWh on dash), April 2011.
Our LEAF's Most Recent Range, Full Charge to Turtle: 75 miles (at 4.1 mi/kWh on dash), July 2012
NOTE: Longer maximum range is possible if the LEAF is driven more conservatively. Many LEAF owners have achieved range of well over 100 miles.

Month:  July 2012
Total Miles at Month End: 14,870 
miles
Miles Driven in Month:  770 miles
Electric Power Used for Charging in Month: 222.3 kWh (measured at wall power source, includes public charging)
Public Charging in Month, Power Use:
 0 kWh 

Charging at Home in Month, Power Use: 222.3 kWh
Energy Efficiency, Month of July 3.46 miles/kWh (wall to wheels)

Energy Efficiency, Month of July:   4.12 miles/kWh (in car main dash display, battery to wheels)
Efficiency Wall to Wheels in Month at 240 Volts: (3.43/4.2) = 84%
Total Charging Energy Used, Lifetime:  4,580.2 kWh (Includes public charging)
Energy Efficiency, Lifetime:  3.24 miles/kWh (wall to wheels)
Energy Efficiency, Lifetime:  30.9 kWh/100 mi (wall to wheels)
Number of Home Charging Days in Month: 22
Most Electric Energy Used for Charging in a Day in July:  17.9 kWh  (4.7 charging hours)
Most Electric Energy Used for Charging AT HOME in a Day in July: 17.9 kWh (4.7 charging hours)
Least Electric Energy Used at Home for Charging in a Charging Day in July  5.1 kWh (1.3 charging hours)
Average Electric Energy Used for Home Charging in a Charging Day in July
10.1 kWh  (2.65 charging hours)
Household Power Used for Month:  785 kWh (without car charging)
Total Power Used for Month:  1007 kWh (includes car charging)
Solar PV Power Generated for Month:  887 kWh
Net Power Used or Sent to Grid for Month:  120 kWh net used
July Electric Bill, So Cal Edison, Schedule TOU-D-TEV:  $-58.30 
 (A credit in this amount will be added to our net metering total charge for the year.)
Solar Net Metering Year Total Cumulative kWh Used at Month #5:  954 kWh (Total kWh net used for the net metering year. This is total household and EV charging usage minus solar PV generation.)

Solar Net Metering Year Total Cumulative Cost at Month #5 -$72.83 (Total energy and delivery costs for all power usage for the net metering year.)
Cost for Charging Car in July:  $0.00
Cost per Mile:  $0.00
Cost for Charging Car, Lifetime: $0.00
Cost per Mile, Lifetime: $0.00  

(If We Didn't Have Solar Power, Est Cost for Charging Car in July: $28.90)
(If We Didn't Have Solar Power, Est Cost per Mile in July: $0.0375) 
Average (Mean) Miles per Driving Day in July:  26.6 miles

Average (Median) Miles per Driving Day in July:  26 miles
Longest Day's Driving in July:  75 miles
Longest Day's Driving in July Without Mid-Trip Charging: 75 miles
Shortest Day's Driving in July:  5 miles
Number of Times we Took the Prius Instead of the LEAF Due to Low Charge: 3
Unexpected Low Charge and Unable to Reach Destination:  Never