BMW i3 Driving to Net Zero Energy – Powered By Sunshine – Month 10 Update


Month 10, Back to the Future, Back Below Zero

The day in our collective technological evolution is here when you can live in a home and drive two cars typical mileage with no utility cost and no gasoline cost. All powered by the sunshine harvested on the roof of the home.



More importantly you can do so at 15% the overall cost as compared to utility supplied electricity, and gasoline purchased at the gas station. With this emission free combination, you can reduce your overall GHG emissions from 40 tons per year per household to two or three tons per year.

*Editor’s note: This post appears on Peder’s blog. Check it out here.

The info chart that the Koch Brothers don't want you to see.

The info chart that the Koch Brothers don’t want you to see.

It’s clear to us after month 10 and once again going below the zero line (we are producing more than we are using for our home and cars) that we will end the year with credits for 9 months and cost for 3 months resulting in an annual energy credit of $650 – $700. Our overall net usage will be around 600 kwh.

Screen Shot 2015-04-01 at 9.50.12 AM

You can see when we took a 4 day vacation away from home

Screen Shot 2015-04-01 at 5.00.30 PMScreen Shot 2015-04-01 at 10.13.01 AM

It’s also clear that in in the near future, batteries will hold higher densities of energy and will be less expensive, electric cars will become less expensive and go farther, and Solar PV will become less expensive and produce more electricity.


So this is not mission accomplished and as good as it gets… but rather mission started and it will become even better in the future.

As the year unfolded it became clear that we would be driving 23,000 miles not 20,000 miles as planned, and we had a French exchange student living with us for several months. A few other anomalies in the year led to higher usage than anticipated. These extra miles and extra persons will in all likelihood push us just slightly in the plus category for overall energy usage for the year. Life is a grand adventure and unpredictable.

Still two months to go so we will see 🙂 Feeling awesome!


For the last several years we have been a two EV family and we have not used any gasoline in our day-to-day lives. However, the rest of our transportation system is not at the same place we are, so when we vacation three or four weeks a year, we are using gas.

Planes, trains, boats, buses and car rentals we take when on vacation and when we do we are burning fossil fuels. During the past several years we have taken one or two road trips a year renting or swapping cars with a family member.

BMW i8 in the house!

It’s rather like a dream, but this month we took delivery of our third car, the BMW i8. Yes it uses gas and yes we have taken it on an epic road trip across the Southwest during a vacation. This is no different than any previous years road trip except for the i8 is a plug in hybrid with better gas milage.

For the remainder of the year the i8 will be a weekend car with the i3 as my daily driver. In a few weeks I’ll post about why we bought a BMW i8.

BMW i8

BMW i8

Sunshine is a transportation fuel.

Thanks for reading and commenting as always!

(Past “Driving To Net Zero” articles)

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14 Comments on "BMW i3 Driving to Net Zero Energy – Powered By Sunshine – Month 10 Update"

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I added another 15 panels (3.7 KwH) in Jan to cover charging the Leaf (and then some). As a result, in March we went full zero net energy (as opposed to zero-net-bill) for the first time ever.

If I ignore the very small number of miles driven around town in my truck, we are now fully zero fossil fuels on the house (electric everything).

Yesterday we generated 65 KwH, can’t wait to see that peak in June/July!


You write that your i3s are getting ~4.2miles/kwh, and the numbers in your chart support that. That seems a bit high to me; is that kwh of “filled” battery? I know some people had done studies and put a meter on the utility side of the EVSE, only to find that their mpkWh was about a mile less than the car would tell them. Just curious if you know what you’re really getting?

A driver can certainly increase the reported efficiency of the car, that is increasing the MPG for a gas guzzler or the miles per kWh for EVs, by “hypermiling”, which means using driving tricks to reduce fuel/energy consumption. Extreme hypermiling can increase the reported efficiency a surprising amount.

The difference reported here doesn’t appear to be an extreme case, but it certainly is an indication the people generating this report are some distance out of the mainstream. It may not be accurate to call this “cherry-picking” figures, but it certainly isn’t representative of what the average person could expect.

The key to all of the above is NET ENERGY METERING, i.e. using the grid as the perfect battery at little cost.

All the Investor-Owned Utilities (IOUs) e.g. SDG&E, PG&E, LADWP are opposed to NEM. It most likely won’t survive in its current form for long. So don’t start counting your 25-year payoff just yet.

We the public should take a more active role in letting California Public Utilities Commission (CPUC) and our lawmakers know how we feel about this.

Exactly. In GA there is no net metering so you have a much longer ROI timeframe. Still doable just not as easy. I’m just waiting for stationary battery costs to come down and then I won’t need net metering or the utility company.

And electricity is so damn cheap that even in tier 3 you only pay $.09 kWh.

Hence the fixed battery storage system that Tesla will announce soon. Once the cost of storing your own energy produced is cheaper or at parity with using the grid as a giant battery early adopters will go this way. In the end it is all just really a math problem.

Indeed. The interests of the investors are shortsighted. Profits over less pollution, more health, stable weather…
So glad we have a publicly owned utility here. There were attempts to privatize it that were derailed when Enron happened.
My 10kwh system covers our energy use overall (excess in the summer, less in the winter). We also get paid double by the utility for what we produce compared to what we draw from the grid.

But the IOUs are all heavily regulated private monopolies, so we just don’t let them kill net-metering. As you point out, make sure the CPUCs know we want net-metering.

I don’t want the utilities to go bankrupt and tweaks should be made as needed but net-metering needs to stay around. It is a great program for adding solar PV right where it is consumed such that no new transmission lines needed.

These are obviously cherry-picked numbers, and therefore, sadly, the comparison is without any value.

The average distance driven annually by American drivers is between 13,000 and 15,000 miles, substantially lower than the 20,000 miles cite in this skewed comparison.

We need more -honest- comparisons of plug-in EVs vs. gas guzzlers, and use of solar power vs. the average home owner’s electricity consumption. Using dishonest figures only feeds the opposition of those fighting against the “green” revolution.