Published Thursday February 20, 2014:  Updated 1/1/2015

Falling Short of Net Zero

One year ago, I calculated that it might be possible to run our entire household, (vehicles, lighting, appliances, cooking, HVAC and domestic hot water), effectively powered solely by the grid-tied 6.2kW solar array. On paper, this looked plausible.  It was a great attempt, but 1 year later, things didn't go exactly as planned. 

Things that increased our energy usage above what was originally estimated: 

  • Basement apartment addition with its own kitchen appliances and bathroom (600 kWh/year).

  • Additional person living in the house (estimated 500 kWh/year but I still love you mom).

  • A new pet reptile, (a bearded dragon) with its large, heated, illuminated cage (275 kWh/ year). 

  • Added a second electric vehicle (A Nissan Leaf driving 8000 miles ~2000 kWh per year). 

  • Unusually hot summer and unseasonably cold December led to higher than estimated air conditioning and heating energy usage (~750 kWh/year).

  • HWG and electric water heater initially not working together efficiently (added an extra 300-500 kWh before bugs were worked out).

  • Wasteful mistakes like leaving lights on and appliances running (180 kWh/year).  

  • Leaky hot-water faucets (70 kWh/year).  

Over the past 12 months (March 1, 2013 to March 1, 2014), total energy consumption was 14,498 kWh.  PV production was 9585 kWh. Usage exceeded what the PV panels produced for the year by 4893 kWh.  

Most of this additional usage occurred during the dark, cold winter months (November-February) when the ground-loop heat pump usage was higher and solar PV production was low.  

Wow!  $143 for electricity for a single winter month?  

Keep in mind, this is the bill for ALL our energy usage.  House heating, hot water, appliances, lighting, cooking and powering 2 electric cars. Due to the low sun-angle this time of year, the PV panels didn't collect much energy either to offset this usage.  
We used to pay $5500 annually for energy (gasoline, natural gas and electricity). Over the past 12 months, we paid less than $500 for our energy, all without any reduction in our standard of living, (if anything our house is now more comfortable, luxurious and healthy than ever before), so I guess it isn't the end of the world that we didn't meet my goal of being truly 100% net zero. 

We still have to live and we still have to drive places right?  While some inefficiencies and wasteful practices can be corrected, reduced or eliminated, the rest are here to stay. So the solution isn't to make cutbacks or to go without, but to simply add more PV panels. 
It will only take installing another 2.8 kW of PV to truly be, 100% net zero. 

While adding more PV is a simple and affordable solution to becoming net zero, I wish there were a renewable energy source available in the winter time that was as common as sunlight is during the summer time. 

This would make renewable, emergency backup power much easier to put in place. Wind would be a good option except wind speeds in our yard only average 2.4 mph, (though we have had some excellent windy days). That's an area in which I need to do more experimenting.  

12/22/2014 Check out our latest experiments with micro-wind energy in the backyard, (sound quality is poor so make sure sub-titles are on). 

Update 1/1/2015:

The results are in for 2014. After a full year of living in an all-electric house, going to an electric clothes dryer, and exclusively driving all-electric cars, here is our energy usage. 

Nine more solar panels will do the trick to get us to net-zero but perhaps this year we will add 16-18 more PV panels just for good measure. Even with making more efficiency improvements, with kids growing up, (and eventually getting drivers licenses), our energy usage will sure to increase. 

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