BMW i3 Driving to Net Zero Energy – Powered By Sunshine – Month 7 Update


7 Months In…Old Man Winter Visits..Predictions for the New Year

A few family vacations had our mileage and energy usage down for this month. Unfortunately, old man winter brought our energy generation down as well.

Our first month of a utility bill that does not begin with a minus sign.

Our first month of a utility bill that does not begin with a minus sign.

It was a wet and rainy month so less Solar PV production.

It was a wet and rainy month so less Solar PV production.

Some travel away from home reduced the amount of kWhs used by the cars.

Some travel away from home reduced the amount of kWhs used by the cars.

We continue on a great glide path for net zero energy cost for the year for the house and our two electric cars. We will achieve this milestone next month, four months earlier than expected, when we receive our utility true up bill for the year. We anticipate a $50 refund from the utility, a $450 credit to our account for electricity, and a $270 natural gas bill for the entire year.

Regrettably, our utility does not let us transfer the electricity credit to our natural gas bill. The result is the credit goes as a gift to our utility.

A $40 utility bill, but still running a huge remaining credit over 11 months.

A $40 utility bill, but still running a huge remaining credit over 11 months.

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

This may come as a surprise, but we calculate our saving to be somewhere between $150k and $200k not adjusted for inflation, (that’s enough to buy a BMW i8 ) during the past 7 years and the next 20 years.  We installed the Solar PV system in 2007 and paid off the system with utility and gasoline savings in April of 2012.   Since 2012, we have been saving $8000 to $9000 a year in utility cost and gasoline cost.

We are driving and living with zero energy or gasoline cost.

We are also on a good glide path for net zero energy usage. It’s important to emphasize that we do have some natural gas use. Our hope was to be three or four thousand kWh more in generation than usage to offset the natural gas use. As the year has unfolded, we are driving about 20% ( 4000 miles) more than planned and we have been hosting an exchange student for the year.

We are demonstrating that it is possible, practical and economical using today’s readily available technology, to construct an energy efficient house, to drive amazing and practical electric cars and to provide the energy for the house and the two cars in the garage via solar PV, all while improving the quality of life and economic situation for the family.

We hope for the day in the near future where this is commonplace throughout the country.
As old man winter settles in (yes we have winter in San Diego) we are enjoying the preconditioning aspects of the BMW i3 and occasionally the fast DC charge abilities of the car. Last week for example we were on a 130 mile RT drive and used the fast DC charger in Fashion Valley San Diego to give us the range to return home with about 20 minutes of charging. Julie and I sipped on a beer in a nearby restaurant while we waited. In the pre DC fast charge world, that would have been a 3-5 hour recharge.

We are very fortunate in California to have a fast growing fast charger network that really enhances the practicality of the BMW i3 and all EV’s that can fast charge.   Fast DC is a game changer and should be standard equipment on all EV’s.

A few predictions for the 2015 New Year and beyond:

As a veteran of EV’s with over 110,000 miles of driving in several models beginning long before there was a level two J1772 standard or public charging infrastructure, I see a “One-Two–Three punch” on the near horizon that will end the dominance of the gasoline car.

  1. The lowering cost of EV’s, Solar PV, and renewable energy sources. This will continue to progress across the county with visionary utilities like NRG and other solar companies leading the way. EV’s will continue to be lower in price. Car drivers will simple find it easier and cheaper to fill up at home. Happening now. (Bonus… this downward cycle will continue and accelarate over the next several years)
  2. The rapid deployment of Fast DC charging equipment across the country.   Beginning at both coastlines then moving to larger cities across the middle of the country, Fast DC chargers will appear seemingly almost overnight. BMW and Bosch broke new ground with their relatively inexpensive fast DC chargers and other manufacturers will soon follow.   Happening 2015 to 2017. (Bonus…look for utilities to get in the charging game in a big way thanks to recent CPUC rulings.)
  1. The lower end “standard” electric car will have a 125-150 mile range. High end range and moderately priced models will offer double that range. This nearly doubles the current norm of around 80 miles for most of the EV’s in today’s market.   Happening in 2016- 2017, (Bonus…look for a shocker of a battery breakthrough in 2016-2017 time frame that will propel EV’s even farther by 2020) These three advances will result in:
    A 150 mile range EV that can be recharged to 85% in less than an hour when on a road trip,  and charged at home with electricity that is cheaper and more convenient than gasoline while you sleep.…and the world of transportation and energy will then change rapidly and forever.

A Happy New Year filled with sunshine to all!

Thanks for reading and commenting.

BMW i3

BMW i3

(Past “Driving To Net Zero” articles)

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.

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32 Comments on "BMW i3 Driving to Net Zero Energy – Powered By Sunshine – Month 7 Update"

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How do you keep the snow off the panels?


For Peder – by living in San Diego.

For me – I don’t bother. It snows nearly constantly from December through March here, so it would be a full-time job. Plus with the short days and heavy cloud cover, even cleared panels would produce minimal amounts of electricity.


For my friend in NY, the panels are set almost vertical in winter to catch the low sun.


LOL! Not much snow out here.

But I’ve thought a bit about this since I have family in Minnesota. Basically, you can put the panels at steep angle and that will help. But largely . . . don’t even bother. If you have snow, then you are probably not getting much sun anyway. The sun will be low on the horizon and the days are short. So what if you have a couple months without collecting?

I’m in California and there has been no snow. But the days are short and it has rained a LOT (which is great), so I only collected 323KWH last month. It wouldn’t be a big deal to lose such months. In the summer, I can collect over 1000KWH.

So basically . . . I wouldn’t worry much about losing a couple months to snow covered panels. If it is easy to sweep them, then fine but don’t do anything dangerous trying to collect $30 worth of electricity.

In NE Tennessee we get some snow and to our pleasant surprise with a combination of the slope of our solar panels, the slick glass surface and the dark color of the solar panels, it is the last place snow will lay on and the first place it slides/melts off. So for us snow is not an issue. I have a picture with the roof covered in snow but the solar panels free at

We too are very close to net 0. We were were going to be net 0 this year but we just purcashed a second EV. So it is likely we will need to add a few more solar panels.


I couldn’t find the pic of the snow covered roof and snow-free solar panels. But I did find some great pics and info about ICF’s and SIP’s, and a great tip about placing the heat pump on the east side of a house to shade it during summer and still catch the morning winter sun. Thanks!


Thanks Spec9! I dunno how I missed it.


So when is it time to get rid of that natural gas heating and get clean heat too?

M Hovis

A lot of us heat with a fully programmable pellet stoves. The pellets are pressed from wood shavings from the furniture and hardwood floor industry.

Even after a cold dreary December in the southern US and after the Christmas tree, outside lights and all electric miles driven, and cooking the roast beast, I still netted $28. Like Peder, I offset my power to the grid. It is likely that our utility, Duke Energy will eliminate net metering in the near future. I guess I will look at a battery with a big red “T” on it around 2018.




Does a pellet stove release a lot more particulate matter compared to natural gas heating?


Dedicated pellet stoves have very low emissions of particulate matter but more than natural gas heating.
That’s why I would recommend a pellet stove preferable as a compliment to a zero-emission heating system as comfort heat once in a while.
Maybe a heat pump plus a pellet stove. Or a pellet boiler in combination with a solar heat system or so.

Anyway, in the total sum of things almost everything is better than fossil fuels like natural gas.


Thanks for the response.


Not the optimal solution, but still better than natural gas.

There are so many heating solutions that it should be the easiest part to fully replace.

My personal favourites are geothermal heat pumps, but they need a fairly cool climate to make sense.

Otherwise air/water heat pumps or air/air combined with solar heating.

Another favourite is district heating that (also) make use industrial waste heat. Transfering a problem (unwanted heat in industries) into a solution (wanted heat/warm water in your home).
But district heating of any kind is something you need a functional community nearby to pull off of course.

Burning biomass at home works, but preferable would be a centralized biomass cogen plant with district heating then.
Every apartment building/multi-dwelling units should have district heating.

There are many solutions, combined or used separately.
And not to forget about energy efficiency which is very useful since many houses are old or built with a poor energy standard. Basic insulation, 3-panel windows and stuff like floor heat (which gives a higher comfort at the same total energy used or same comfort at a lower inside temperature).


We built a passive solar straw bale home. No A/C, no furnace. It maintains a range of 68 to 74 year round (that’s 74 when it’s 115 here).

Water heaters are electric on demand, stoves and ovens are electric.

But we do use a lot of power when those stoves are going (two houses – main with a full granny unit).

I just installed another 15 panels (43 total) to cover Leaf charging and should get an additional avg of 7 kWh/day above that, so we may go true zero net energy this year.


Nice. I like the back to nature approach in a modern version. The things you can do when starting from scratch.

Do you have any public documentation of the building? Any tips and trix and things to have in mind? Or problems appearing after it was built?


I built our home in 2006 and although only 8.5 years ago, it seems like an eternity as far as the green energy equipment is concerned.

State of the art back then was a natural gas tankless water heater (which we love) highly efficient natural gas furnaces (three, each independently controlled) and a super thick shell (r21 in 8inch thick walls and r42 in the ceiling) a trombe wall made out of concrete that heats up through the south facing windows, with argon filled dual glazed wood windows and a natural gas dryer.

In our area, house heating is only a concern one to two weeks a year, so the majority of natural gas use comes from the tankless water heater and the dryer. This is where our 17 year old female exchange student comes into play as a large consumer 🙂 I’ll let these appliances go through their life cycle but when it comes time to replace we will be changing them out to electricity.
Thanks for all your comments!


Great. I like that you have a plan for it. One reason for me picking a bit on your last sources of emissions (not counting what we eat, do, buy, fly with, or the other endless sources of emissions) is that too many people forget about heating and about natural gas.

Sometimes it feels like people think that coal, oil electricity and transport are the only sources of emissions and energy (and sometimes they don’t even care about oil and transport either).

I assume the gas company doesn’t have any option for biogas? 😉


Holy crap! You have 8inch thick walls in San Diego? Most of california is standard 2x4s with zero insulation.


Your efforts are inspiring! Any pics?


I had a full blog on the project, but lost it when Apple abandoned iWeb. Will see if I can share some pictures with you.

And glad I’m not the only one expecting a huge reduction in power usage when the teenagers leave… 😉


Just in case you want to get snow off I recommend the Avalanche. This product is much more efficient and will not damage panels as a snow rake could, and probably would. I have one, cost about $60, works great even if you don’t have solar on you roof.




Nice. I think I need to put solar PV on my parents house in MN. They could use that to remove snow . . . or not. It really wouldn’t matter since there is not much sun then.

Actually, I flew out for Christmas AND THERE WAS NO SNOW! IN MINNESOTA! Climate change is real.

I have commented on your articles a few times, the last time being when I got a mostly pleasant response about the somewhat purist snobbery regarding my Volts (which use gasoline) compared to your purely electric i3s. I have two homes and, for the most part, get to spend my winters in Florida, where I have my solar panels. Unfortunately, over the last year, I lost my battle to put solar on my dock in NY due to STUPID bureaucrats in both the federal and NY state governments ( ) However, upon reading about the natural gas component to your energy usage, I must reinforce the TOTALLY non fossil fuel approach that can be taken. When purchased in 2007, our NY home was heated by propane. However, abhorring fossil fuels, I ditched the propane a few years ago. I now have a GE Geospring heat pump water heater and primarily heat my home with Mitsubishi Mr Slim heat pumps. I also have a secondary combustion (I MUST emphasize this, as we cannot all burn wood without burning it efficiently!!!) fireplace insert which I have used occasionally, although my NY time has seen temps in the teens and found Mr… Read more »

flmark, I am very excited to see the new Volt coming soon, and wish it much success!

We see a lot of Volts here in San Diego.


I’m still working off the extra credits that I earned last year. 🙂 But since I heat with nat. gas, that will eat up my credits. I need to insulate more to reduce my natural gas usage.

I’d like to get a heat pump but since I live in California, I don’t know if it is worth it.


We don’t get to roll over our credits or use them for natural gas in SDG&E territory.

Each and every utility has different rules which makes it hard.


I don’t get to roll-over my credits, I got a $204 credit for overproducing solar electricity. I think that is a California law. But it is not a great deal, they pay you at around 4 cents per KWH, so I’m losing money on the deal. I over built my system because I wanted to be sure to produce more than I use.

Right now, I don’t drive much but if I get another EV and start driving more, I can easily add another 2KW of panels to the system. But there is no point right now.


Yeah, from a purely financial perspective, it’s not worth taking the reimburse option here (PG&E), with those wholesale rates. Better to do the TOU metering and leverage peak vs night time rates.

You just have to decide on zero-net energy or zero-net bill. The former being the more altruistic route. 😉


Yeah, I wanted to be able to completely zero out my bill so that I could say that I generate all my NET electricity (which includes the EV).

I don’t my over generating a little bit. I still use natural gas though for various heating tasks . . . I need to work on limiting that with insulation & other things.