Friday, May 29, 2015

Month 12. Hello Future... we’re here.

Our yearlong journey, "Driving to Net Zero Energy" has now come to an end. Thank you to BMWi, ChargePoint, Inside EV's, Stellar Solar, the Center for Sustainable Energy (CSE)  and SDG&E, for following us and supporting us during this past year.

My hero is an imaginative and creative child.

Our two BMW i3’s and our home were powered by harvested sunshine from a small portion of our roof with zero gasoline cost and zero utility cost for the last year…for forever.    We did it!

We believe we are the first household in the world to do this with full documentation. We also believe that there are dozens, perhaps hundreds of other households who have accomplished the exact same thing without going though the painstaking detail and very public process of sharing private and personal information.

Why this scope & scale?

There’s something traditional, in an American sense, about a home and two cars in the garage.  We are a nation that came of age the past 100 years concurrent with the era of the automobile. For better or worse, our homes and cars are together entwined with the embodied energy of our built history. For better, we can now power both our homes and our cars with renewable energy, in our case with sunshine.  We can also effect change on this personal level of our own lives, it’s harder to do on a citywide or national scale.

“The inertia of the status quo, is a powerful foe of progress”  

There is safety and security in the status quo but there is no future, only a past.  

It is for this reason that we decided to do the Driving to Net Zero Energy challenge,  why I write, why I  share as broadly as possible our personal and private information, why I serve as a Planning Commissioner of the nations 5th largest county by population, so that I, that we collectively, can help “break the broken” status quo, and move ourselves, our families and our cities to a far better, richer, healthier future. 

The gas station down the street, the power-plant in the next city over, and the oil wells across vast seas and deserts, have served our households and transportation energy needs during the past 100 years. They are now giving way to the homeowner who fuels their own home and cars with electricity from solar harvested from the roof of their home.  An ecosystem of a dwelling, an energy plant and transportation all contained in one unit, enriching the owners whether a home, a commercial hub or a city.

As a society, we have arrived at a destination, an intersection of our historic calendar and our always-advancing technology prowess whereby today, our cities, our homes and our electric transportation choices can be powered by renewable energy generated by a homeowner.  During the next 20 years, our country and our individual households will see changes in energy and transportation that are hard to comprehend in their magnitude and benefits to our environment, safety and health, and to our household budgets. 

Our year in review:

Let’s start with a couple of 800 lb. gorillas and get them out of the way.

1.     Although we have no cost of energy or gasoline for our home and two cars, saving us about $8000 a year, we are not 100% energy independent.  We are grid connected; we have had a very slight amount of electricity use for the year and a small amount of natural gas use.   There is no economic reason to go any farther than below zero cost,  but half our goal is to be energy neutral, this has still not been reached.  Our cost are zero and our usage is de minimis.  You’ll see this in the charts below.

2.      If you think you can plan a year in the future, think again. Our year has unfolded with several unexpected events not foreseen during our planning for the year. 

We made a last second decision to host a Rotary International French exchange student for a year so that two young students, one from France staying with us, and one from Coronado going to France could have the experience of living a year abroad.  Another person in the household with a full head of hair and an energy hog hair dryer added to our annual total. I actually calculated her monthly (85kwh) energy consumption, I know, that's a little obsessive, compulsive.

We expected to drive 20,000 miles this year; we ended up driving 21,477 miles.

We lost a family member, priorities about energy savings we’re inconsequential during these months of care giving and grieving.

After three years of being a two EV household, after working with and Field Test driving for BMW during the past 5 years beginning with the BMW Mini-E, I had the opportunity to buy a very special one off Electronaut Edition of the BMW i8.
During the last 2 months of the 12 month "Driving to Net Zero" challenge, we were a three car household.  The BMW i8 took a couple of long road trips and it’s a very special collectible car that will see a road trip or two a year and a scant couple of hundred miles a month.   Our two i3’s remain our daily drivers. Our challenge was 20,000 miles a year in the two i3’s which we surpassed.   The BMW i8 (a plug in gasoline hybrid) is a dream and a collectible and we are fortunate to own such a car.

Even as a two EV family before the BMW i8, once or twice a year we would borrow a gasoline car for a long driving trip. We take the occasional plane flight, cruise ship, train, bus and taxi, all of which consume gasoline, avgas or diesel.  So we possess no "EV purity card" and never have, as the rest of the transportation network is not quite as advanced as our household.

We realize how fortunate we are in life, and that we are not the statistical norm. However in California at least, Solar PV is making its way to all income levels and housing types and EV’s can be leased or purchased for well under $200 a month.   Living Net Zero does not need to be done in a custom home with BMW’s in the garage.

Lastly, we think that’s what makes this "Driving to Net Zero" challenge so special. It’s a real home with real people, real lives that are wonderfully unpredictably complicated, covered over the course of a year.   It’s not an unoccupied home on a University campus built by a car maker. It’s not a theoretical calculation of energy use by a home builder or a University.   It’s real, it’s us, "warts and all" for a year.

Now our year of data in review  :) 

Julie is a more efficient driver, and a credit for the year of -$751

Our annual credit for unused electricity, $-751.57
Our annual gasoline cost for two cars, 21,477 miles, $0.00
Our annual natural gas cost, $279.89
Our annual total cost of energy $-471.36

Last year after four winter months we had used 1150 kWh of electricity.
This year after four winter months we have used -349 thanks to one
less person in the household and the more efficient BMW i3's.
We expect this trend to continue generating an extra 1200kwh
more than we use for this year, to offset our small Natural Gas use.

Our energy challenge began on May 15th, 2014, when we received both BMW i3's, the most efficient car in the USA.  Our annual true up bill from our utility begins every year on January 15th.  As you can see we are on a great trajectory for 2015 and we expect this to continue resulting in an overproduction of around 1200 kwh of electricity.  The stronger sunshine summer months are approaching.

Solar Panels occupy about 25% of our roof space as outlined in blue.
Notice all the roof projections were designed to be on the north side 
of the home, thus clearing the way for solar PV on the south side.
Our ChargePoint usage graph for the year.  Our ChargePoint CT 4000 was
installed the first week of June so a few weeks of date were hand tabulated.
It's a heartbeat of energy use. The gaps are mini vacations away from home.
A monthly view of the same data.

A total of 5061 kWh of electricity was used to drive 21,477 miles in two BMW i3’s.

Julie averages 4.3 miles per kwh 11,862 miles / 2717kWh
Peder averages 4.1 miles per kwh 9615 miles / 2344 kWh

We both have our own port and swipe our separate ChargePoint cards to activate
the individual ports. This is how we tabulate each car and driver separately.
Love the BMW i3's, that they plug into the sunshine on our roof.

When you live in a home and drive EV's powered by solar, every
aspect of emissions is reduced, thus improving the air quality for all.

Before our solar and electric cars, we had fun powerful but gas guzzling cars
and a high cost of gasoline and utilities.

Today, this picture and graph represent our cost. The $245 was
an estimated cost for nat gas when this slide was made several months ago.
It's a complicated formula that varies from utility to utility.
In our utility, any unused credit is not refundable.  Thus no check
for $751.  We did however receive a check for $36.68!
Like I said, it's complicated! The utilities set the slot machine payouts.

This was calculated when gas in our region was $3.50 a gallon.
Today's gas prices are $3.93 a gallon.
Now you see how I can afford to drive the BMW i8 :)

Our 8.5kw Solar PV system generated 13,546 kWh for the year. This equals 1593 kWh per kw system size.

A 3.18 kw Solar PV system (3.18 times 1593) would provide the 5061 kwh of power for both BMW i3s driven 21,477 miles.

The total cost of the 3.18 kw PV System is equal to buying gasoline for 2.82 years. An ROI of 35.4%

Driving the BMW i3’s powered by Solar PV, the cost per mile is $0.017 cents per mile. 

If advantageous TOU rates are factored in as our case, the Solar PV system size and cost would be reduced by 22%, the cost is $0.013 per mile.

Driving on Solar PV supplied electricity is 1/10th the cost of driving on gasoline.

In summary:

Thank you to you the reader for following us on this year long journey.  Thank you for your many comments and questions throughout the year.  One of the unexpected joys, and I am so fulfilled when I hear it, is the dozens of times in the past year folks have thanked me for writing and for inspiring them and giving them confidence to do similar, to what we have done.

Just take a small step, a small reduction in energy use or a slightly more efficient car or transportation choice if you can. You don't need to go all "Full Monty" to a make a meaningful contribution to improving your city and your budget for your family.

It has been an iterative process for us the last several years beginning with solar in 2007 and with two gasoline cars and a toe in the water with the BMW Mini-E in 2009 to where we are today.

Get started and change your world,  you can live and drive on Sunshine.

For more information about our systems and cars read the first post, Energy Challenge Introductory Article of this series below.



  1. Three cheers Peter and Julie. Its not getting to zero emissions, its systematically and consciously striving to conserve and limit the use of non-renewable resources. That you did like champions. Great going. Driving an i3 REx and following your exploits have led me to take the next step--solar panels for my home.

  2. Thank you for your comment Dr.B,

    Glad to hear the i3 will soon be powered by solar!


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  4. Thank you Peder for your detailed year review. I unfortunately did not keep any records of my usage like you did but I installed my 17 solar panels in Dec.2013 and got my i3 in June 2014. It's a great feeling to know that my home and my car are fueled by Sun Power. I hope that from reading your review, many others will get encouraged to go green. Happy E-Driving.

  5. Thanks for your comment Tmondle and thanks for doing what your doing, you know how awesome it feels!