Month Five, Two BMW i3's and a Home, $-718 Utility Credit, $0.00 Cost of Gasoline

The idea is a simple one, harvest endless sunshine from a small portion of a roof to provide 100% of the energy needed to power a home and two cars with zero utility cost, and zero gasoline cost for 12 months.   

Our prior cars were a Volvo S60R and an Infinity G35.
We spent $5000 a year on gasoline and $4000 a year on electricity.

We now drive the most efficient cars in the world powered by sunshine.
The asterisk on the cost represents the cost of natural gas,
which is offset by a larger credit for electricity.
Unfortunately the credit is not transferrable with our utility SDG&E.

So how are we doing after five months?

• We continue to amass a large bill credit now at $-718.
• We have used a net of 11kWh of electricity more than we have produced.
• We are driving 20% more than we anticipated,  now at 10,700 miles.
• We have an unplanned for, exchange student in our home for the year.
• Solar PV is beginning to tail off for the winter.

Less driving in October as we were both away on business for a week.

We have gone into positive energy use from SDG&E of 11 kWh

Summer is now past and we continue on our quest, "Driving to Net Zero Energy Challenge."   After five months of living and driving we have amassed a large electricity credit of $-718 against a natural gas bill of $92  and we have used close to zero (11 kWh,) about $1.50 worth of net electricity.

It's clear to us knowing our past few years of usage, that we will achieve our goal of harvesting sunshine from our roof, providing 100% of the energy needed to power our home and two cars with zero utility cost, and zero gasoline cost for a year.

We anticipate accomplishing this goal four months earlier than planned at our annual utility bill true up in January.  That true up bill will have a big fat goose egg at the bottom with an unused credit of around $-450.

After nine months of driving two EV's
(prior EV's were the BMW ActiveE and Honda Fit EV) and our home energy use,
we have amassed a credit of $-614. We should finish the year with a
 ~$450 credit for electricity against a ~$225 cost of Natural gas.

The harder goal to reach will be actual net zero energy consumption.  It should be pointed out that there is no financial benefit, only cost, once you have a zero energy bill and any effort to conserve beyond that goes as a gift to the utility.

We anticipate being within ~700 kwh of this goal at the end of 12 months so it's going to be very close. If we have a warm and sunny winter/spring we might just make this goal as well.

The unanticipated factors working against us are:

1.  We are currently driving at a 25,000 mile a year rate for our two BMW i3's, we anticipated 20,000 miles.  These 5000 extra miles are the equivalent of 1200 kWhs. 

2. We have invited a Rotary Youth Exchange student from France into our home for the year. Lots of blow drying, curling iron and electronic gizmos :)

Our two BMW i3's 

Sungas and Sungas 2 are amazing cars and we are enjoying them very much. You can feel the lightness and the rigidity of the CFRP, which combined with the regenerative braking, provides for a driving experience unlike any car I have driven before.  I really look forward to a future coupe or sports car from BMW using rear wheel electric drive, lightness, CFRP and strong regen. 

The combination of being the most efficient production car in the world at 124 mpge (5X the average 25mpg car on the road,) being a blast to drive with 0-60 times in the 6.5 second range with slot car driving characteristics and surrounded by the best interior design/materials of any car I have ever seen, is a yet unmatched feat in the automobile world.

With the BMW i3, efficiency, performance, sustainability, high quality design and incredible materials such as CFRP are not in conflict, but rather work together leveraging the strengths of each, resulting in an evolutionary change in how I view the future of the private car.  It's only going to get better as we head into the future. 

More on our experience living with and driving the BMW i3's in an upcoming mid month post.

Thanks for reading and commenting.  You can live & drive on sunshine.

(Past "Driving To Net Zero" articles)

• Energy Challenge Introductory Article

• Update Month 1

• Update Month 2

• Update Month 3
• Update Month 4

Editor’s Note, Peder is the Chairman of the San Diego County Planning Commission. His wife Julie is Director of Curriculum and Instruction at the Solana Beach School District. They have been Field Trial drivers for BMW for five years. Together since 2009, they have driven more than 100,000 EV miles powered from roof top solar.