BMW i3 Driving to Net Zero Energy – Powered By Sunshine – Month 2 Update


Update Month 2, Driving To Net Zero

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.

Solar PV panels on a portion of our homes roof.

Solar PV panels on a portion of our homes roof.


  • Month 2, -118 kWh in utility usage, -$162.57 in utility cost
  • Stats, Stats, Graphs, Graphs.
  • Solar PV as a transportation fuel
A sunny two months has put us below the line, Julie proves she is the more efficient driver.

A sunny two months has put us below the line,
Julie proves she is the more efficient driver.

Our BMW i3's drove 1667 miles using 381 kWh from the wall,  and 22 kWh from 2 public charging events

Our BMW i3’s drove 1667 miles using 381 kWh from the wall,
and 22 kWh from 2 public charging events

GHG reductions for the month for our BMW i3's

GHG reductions for the month for our BMW i3’s

Total utility electric use for our home and two i3's

Total utility electric use for our home and two i3’s

Our BMW i3's used 381 kWh, our home and guest house used 854 kWh. In the 3-4 summer months, we cool a 450 sq. ft subterranean wine cellar so the electricity use is higher than normal for those months.

Our BMW i3’s used 381 kWh, our home and guest house used 854 kWh.
In the 3-4 summer months, we cool a 450 sq. ft subterranean
wine cellar so the electricity use is higher than normal for those months.

You can live well, and live Net Zero Energy. The cellar  is cooled primarily by the stable earth temperature of 64 degrees

You can live well, and live Net Zero Energy. The cellar
is cooled primarily by the stable earth temperature of 64 degrees

You can live well, and live Net Zero Energy. The cellar  is cooled primarily by the stable earth temperature of 64 degrees

Our “True Up” bill after six months. You can see the change in energy use when we began our Driving To Net Zero challenge with the more efficient BMW i3’s in May.

We began our 12 month documented Driving to Net Zero journey on May 15th, 2014 and we’re off to a really great first few months. The BMW i3’s are proving to be super to drive and very efficient cars. We each have approximately 2000 miles on the odometers now and we have had zero issues with our i3’s to date.

It is possible to live in a house and drive two cars powered by sunshine. Soon in the next few years, energy storage will become affordable. A household like ours will be able to make and store some or all of our generated energy, both in the cars and in the home energy storage system, further lessening the load on the grid.

July Focus: Sunshine As A Transportation Fuel

Sunshine is our greatest, most equitable and endless natural resource. Solar PV systems are now blossoming everywhere it seems, like flowers on a sunny spring day. In all fifty states, homeowners, corporations and civic institutions are discovering that harvesting sunshine makes great economic and environmental sense.

I am excited about Solar PV lowering the sting of utility bills. However, the greatest value of Solar PV is when it is used as a transportation fuel which now presents a viable option to help us solve our most vexing national issues caused by our addiction to oil.

What are those issues? National security and defense costs, measured in both blood and dollars. Major cities like San Diego and Los Angeles having unhealthy air quality, with 60% of total emissions coming from the oil we burn in refineries and in our cars and trucks. Our national and family budgets siphoned off by the ever-increasing price of gasoline, as we slowly, voluntarily, export our wealth from our wallets and purses to foreign countries, some that are openly hostile to us.

The inertia of the status quo (oil) is a powerful foe of change. Its strength and certainty comes from the knowledge of today and yesteryear.

Today there are 200,000 plug in cars on the road, approximately 25% of these plug in drivers are making their own fuel for their own car on the rooftops of their own home. That scares the heck out of the profiteers of the status quo.

They’re doing so at a cost that is 15% of the cost of driving on gasoline and fixed in cost forever as sunshine has never raised its price. They are showing us the road to the solution of our most vexing national problem, getting off oil.

We think of our ChargePoint CT4000 Charging Station as a “Gas Station” of the future that fills our BMW i3’s with sunshine electrons from our roof. Just as gas stations have had a foundational relationship with oil companies the past 100 years, I believe that in the next 100 years, Charging Station owners will have a foundational relationship with Solar PV.

It’s a large segment of plug in drivers that already drive on Solar PV, as the prices of Solar PV continues to fall, more and more will choose to drive on sunshine.

In California, our energy picture contains an ever increasing percentage of rooftop solar, utility solar, wind, geothermal and hydro. The future is looking brighter and cleaner than ever.

You can drive and live on sunshine at very low cost.

This is our actual cost of gasoline and Solar PV in San Diego as of 7/01/14.  You can further reduce your cost by approximately 25% with a TOU rate coupled with Solar PV.

This is our actual cost of gasoline and Solar PV in San Diego
as of 7/01/14. You can further reduce your cost by
approximately 25% with a TOU rate coupled with Solar PV.

Next Month: Vehicle Charging Stations: past, present and future and a “surprise” from France that will certainly increase our energy usage.

Thanks as always for reading and commenting.


(Past “Driving To Net Zero” articles)

Energy Challenge Introductory Article
Mid Month Article: The Energy Grid
Update Month 1
Mid Month Article: Does your Gas Station Pay you to fill’er up?

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 100,000 EV miles powered from roof top solar.

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23 Comments on "BMW i3 Driving to Net Zero Energy – Powered By Sunshine – Month 2 Update"

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Why do you think the batteries will last 25 years? That seems like an awfully long time. A gas powered car might last that long with an engine rebuild. Looking at the period warrantied by the manufacturer is more reasonable.


He doesn’t have the cost of the cars in this. What are you talking about?


I had the same question. But on second thought he has just compared fuel costs – not the price of the cars. The comparison would still be valid if new cars were leased every three years.


You are not driving on sunshine, but on the grid, and have been miss-stating that for years, although presumably because you got such a hammering about that now at least note that you are not really doing that at all.

An offset is a very different matter to actually powering your car on solar, and however desirable that may or may not be is simply not the same thing.

Output in winter, not summer, is also the critical thing, and San Diego is about the most favourable location in the US for year round solar.
Try winter in Chicago to test the notion that present solar can really, actually and in truth power a car year round most places in the States.

I have supported solar for 40 years and hate it when people miss-state and overstate the case.

Mark H

Global energy is a recognized concern to practically every nation today. The practice of offsetting solar energy is also widely accepted. Yes Peder’s specific energy charging his EV is from the grid but the argument you are making is both futile and silly.

It is worth mentioning that the late power comes from turbines that can not be idled and this is currently using unrealized power. This is all an encouraging practice up to the point where solar generators are producing more than the grid is using at which point the utilities should be allowed to refuse the generated power and the solar generators will need to add battery storage to their array.




DaveMart with his standard whine. But actually, he IS directly driving on sunshine sometimes. I’m sure the cars are plugged in at times while the sun is shining. And when he plugs them in other places while the sun is shining, well we do have a grid and it is doing its job.

Dave we have a grid for a reason . . . to balance the energy production and consumption around. Why in the world do you expect people break off the grid when installing solar? Do you have a little personal coal plant at your house powering it up 24/7? No that would be stupid. What happens when a coal/nuclear plant has to be taken down for maintenance or refueling? Why do you think those plants should get to enjoy the benefits of the grid but solar should not?


I think he is charging super off peak.


Hi Peder.

Thx for writing the article.

I have a 3 kw system on my house in AZ so I am somewhat able to understand the numbers in the “true up” 6 month bill. but I still have some questions.

As I scan down your peak kwh numbers for each month I see hem increase monthly net input to the gride of like 92 kwh up to 560 or so. Why are the numbers going up? Seems like they should be more constant than that except for some seasonal variations?

Also I kept looking for the size of your system and couldn’t find it although the one chart talks 4000 watts but it I count the panels I come up with more like 7000 watts.


Take a look at some of his earlier articles. I think his system was over 6KW but he recently added more panels putting it to around 8KW.


also if you could explain the NEM charges plus the remaining columns on that table.

What happened to your fit ev?

DaveMart, I don’t think I am misstating my solar use at all. The very title is “Driving to Net Zero” Energy challenge and I often talk about the TOU rates being favorable to generate during the day and charge during the evening. See my prior post. The net generation number during peak is growing for a few reasons. 1. We are into the peak summer months so more day time sunshine. 2. We did a 1kw expansion of 4 panels (on the same inverters) in May, that adds about 130 kWhs peak in the summer months, 3. We put our cellar, which is our biggest energy hog, on an appliance timer so it will not run during the peak hours of 12:00 to 6:00pm. We should have done that years ago as there is enough thermal mass to hold the wine within two degrees during those 6 hours. 4. We are far more diligent about not charging during peak for the 6 summer months when the rates are high. In the 6 winter months the rates are nearly the same so we charge more often during the day. Summer rates in SDG&E territory are now $0.49 peak, $0.22 off peak,… Read more »

Peder . . . if you hit the “Reply” button on a particular message, it will put your reply directly below the message you are replying to so the messages are a lot easier to read in context. 🙂

With my system, I have generated 4.5Megawatt-hours of excess electricity. But I only have one electric car, a small home, and I don’t drive much.


Thanks Spec9,
learn something new everyday 🙂


Hi drpawansharma,

I was going to let my dad drive the Fit EV for the last 11 months of the lease. When I called Honda to ask if that was OK regarding the collision comp insurance that Honda pays for, They told me that I had the option of returning the car to them and that they would then re-lease the car for a two year lease. Apparently there are a lot of folks that are on a list to that. So we returned the car to Honda and it was immediately re-leased on a two year lease to someone else.

I really liked the Fit EV and it was very reliable with no issues, but I like the i3 better and the i3 has about 10% better range even though the epa ratings are about the same for both cars.

A little more info on the “true up” bill to clarify. Our billing year began on January 16, 2014 and ends on January 15th, 2015. We are six months into the billing year. Our Net Zero Energy Challenge began on May 15th, when we took deliveries of our two BMW i3’s, we upgraded our Solar PV by 1kw system size, and we dialed in some other energy usage such as the cellar. So the first four months of our bill were with the 30% less efficient BMW ActiveE, the 10% less efficient Honda Fit EV and 1kw less Solar PV. If we had had the two i3’s and the extra 1kw of solar for the first four months of the true up year, each of these months would have used approximately 200-250 kWh less. So you can see we are tracking very close to net zero kWh, as well as being very far ahead on the cost of energy. It’s odd to start in the middle of the month but that is when the meter is read, and it’s odd to start in May but that is when we took delivery of the cars. It’s the efficiency of the i3’s… Read more »

Hmmm How can I put this.

I guess I will put it bluntly.

It is guys like Peder that the utilities hate.

He’s essentially paying no bills but he is still using the grid. So the utilities have a huge expense and Peder is taking a free ride from their point of view.

This is exactly why my Az utility is changing the rules.

First rule change is if you have solar you MUST be on TOU rates and not exceed a max draw during peak or you are penalized.

Second, if you have excess electricity in your kwh bank an the end of the year you only get 2 cents per kwh. You can’t carry forward unused kwh’s to next year.

The utilities still have to provide 100 percent back up when the sun isn’t out. It’s not like they can cut back on generating capacity just because you have solar. So solar does them no good. It just costs them money. They make less profit.

Mark H

Mostly true George with one exception. The utilities do have to supply when the sun isn’t shining, but they do benefit as well when it is shining. They lose direct revenue, but they save peak demand which is where the real cost are.
Like Peder, I want a long term relationship with utilities and I think they deserve the right to build their business model any way they feel is best. HOWEVER, the individual now has choices as well. And when there are more desirable storage options for consumers, their choices expand even more.

The leadership varies between utilities as stated in your model. How my utility responds to me as a customer will determine how I will respond as a consumer. That is the first time in history that such a statement could even be made to my utility provider.

No, that is just not true. Now of course they don’t like Peder because they essentially lost a customer. However, he is NOT getting a ‘free ride’. 1) Peder is probably paying a month fee to connect to the grid. With my Solar PV system up PG&E territory in Northern California, I pay a $5/month ‘distribution fee’ to help pay for the grid upkeep. I pay that even though I generate more electricity than I use. 2) Peder generates excess electricity during the day which the utility then sells to his neighbors for that nice thick juicy $0.49/KWH price. In return, the utility provides Peder with replacement electricity at night when they generally have massive amounts of excess electricity which costs them very little. Thus, the utility profits off the electricity Peder provides to the grid via rate arbitrage. 3) Peder is making big efforts to use electricity when the utility has excess electricity. He also does not uses electricity and actually produces electricity when the utility has a shortage. This flattening of the demand helps improve the profits of the utility by reducing the need for rarely used ‘peaker’ plants and provides valuable demand when the utility has extra… Read more »
GeorgeS I agree 100%. I am a huge supporter of the energy grid (and all grids, banking, social, communications, food) as they are giant sharing systems and are far more efficient as delivery vehicles. As we transition to a substantial amount of distributed solar and renewables, and as energy storage via batteries come on line, we will need to develop different rate structures than we have now. However, I see that future grid as more balanced, accessible and interactive with far more people earning revenue and not just being a billed customer, as many will be providing a net benefit to the grid. As it is today, I should be paying a small monthly fee for the transmission of my excess energy back to the grid. I already pay the normal price when I pull from the grid. EV drivers should also be paying for road tax in some form, however all cost from driving, including possibly a reduction of health care cost resulting from the cleaner air should be factored into the rate. We have a term we use in the planning profession call “De minimis” it means lacking significance or importance : so minor as to merit disregard.… Read more »

Unless I missed something in the comments above, no one seems to have mentioned charging electric vehicles at work under a solar canopy.

This has virtually nothing to do with the grid, or with buying or selling power to or from the grid, or using the grid as a kind of “battery”.

In this example, solar panels are “grid-less”.

Of course, if you work at night, then how can you charge your car at work ??

This seems to put all the “idiotic solar charging fanatics” in a quandry…

Well —-not exactly….. Your EV can be charging at home while you are asleep during the daylight hours, resting up for your night job.

These are realistic, practical examples where solar power and charging are entirely independent of the grid.

Thanks for sharing your experience. I’m new to EV, having just driven the i3, and having my preconceived notions about them totally turned right-side up.. Besides our 1st EV, (possibly followed by the i8 next year) I’m beginning to educate myself to solar panels and the possibilities of doing what you are. I’m also new to So Cal from Newnan, GA, and am very excited how much more socially responsible & progressive this area is than my old town. Please keep posting your experiences as they are super helpful to newbies like myself. Cheers – JB