Misplaced Megawatt-Hours
Published Saturday January 30, 2016: Updated March 2, 2016

Misplaced Megawatt-Hours
I seem to have misplaced 2.9 Megawatt-hours. Has anyone seen them? 

Ever since June of 2014, our entire household and vehicles have been powered entirely by electricity. 
  • 2 electric cars, plus plug-sharing for visitors. 
  • Lighting of course
  • Appliances
  • Hot water heating
  • All home heating in the winter time (ground-loop heat-pump)
  • Central air conditioning in the summer time (ground-loop heat-pump)
  • Mom’s basement apartment
  • All cooking/food preparation – 95% of all our meals are homemade
  • Grow lights in the winter time – Small indoor hydroponic herb/salad gardens. 
Based on our 2014 energy usage and the new PV solar array addition in March 2015, I estimated that all our energy usage for 2015 would effectively be 100% solar powered and there would be about 1000 kWh of excess of solar energy available for future expansion. 

Well, instead of an excess, my energy surplus ran out two months shy of the net-metering period end date. By the time late February comes around and I start building up energy credits again, our household will probably have consumed 1200 kWh (about $120 worth) beyond what the solar panels produced for the net-metering year. Energy credits are tabulated on a March 31st to March 31st calendar year. 

The solar array performed as calculated, so where did all that extra energy go?

Year       Solar Energy Production                Energy Consumption
2014      -9,440 kWh                                     14,706 kWh
2015      -16,049 kWh (more PV added)       17,577 kWh
Delta                                                               2,871 kWh

That’s a difference of almost 2900 kWh for energy consumption between 2014 and 2015. I don’t see any extension cords running to my neighbors houses, although they joke with me that they are going to do it. So what used all that extra energy in 2015? 
To modify Lord Kelvin’s famous quote into my own, If you CAN Measure It you CAN Improve it. 
Thanks to the energy monitoring hardware installed in my home, I can keep tabs on how much energy my household uses and for the most part, know where it is going. Analyzing the data for 2015, here is were the missing energy has gone. 

Raj vs Geo EV:
In January 2015, I retired my beloved Geo EV and started exclusively driving Raj, my 2012 Nissan Leaf. Even thought the Leaf, being 100% electric is a crazy energy efficient car, my Geo EV had it beat. The Geo was a much smaller, lighter car and used about 40% less energy. So essentially after driving 9500 miles that year, I consumed about 1000 kWh more in 2015 than I would have had I continued to drive the Geo EV. 

I average about 3.65 miles per kWh driving the Leaf as opposed to 6.04 miles per kWh in the Geo EV. These figures are based on total energy to charge the car's battery, not just energy consumed by driving the car.
Note: Nissan Carwings energy data only accounts for energy used while driving. It does not account for charging inefficiencies or energy used pre-setting climate controls while the car is parked in the garage or away. For my conservative driving habits, Carwings reported energy usage 21% lower than what it actually took to re-charge the car. 
Electric Clothes Dryer
Until June 2014, the clothes dryer (our last remaining gas appliance) was still running on natural gas. Since then it has been 100% electric. For 10 loads per week and with hot attic air feeding the drier during the hot attic months, energy usage averages about 100 kWh per month or 600 kWh total for the remainder of 2014 and 1200 kWh for 2015. So for 2015, dryer energy usage would have been 600 kWh more. 
Clothes Dryer Cycle

Apartment Space Heaters: 

The entire house is under one HVAC zone and my mom lives in a little basement apartment in our home. Since the basement is always colder than the upstairs, we added supplemental resistive heating so she can crank it 73-74°F while the rest of the basement hovers around 67-69°F through the winter months. This extra resistive heating adds about 3.5 kWh of energy usage per winter day, (~400 kWh each year).
My mom's electric fireplace, (solar powered of course).

AeroGardens:
I picked up 2 used hydroponic Aero-Gardens for a total of $40. While growing herbs and salad is really enjoyable and delicious, each garden consumes about 33 kWh per month. I started these in mid-December, so together they used an extra 33 kWh (for the last 2 weeks of December). 
Add it all up:
Clothes Drying                 600 kWh additional 
Raj (2012 Leaf)               1000 kWh extra
Heat Pump                      1000 kWh extra
Water heating energy      -150 kWh (a reduction)
Resistive space heating   400 kWh extra
Hydroponic Gardens        33 kWh
For a total of                   2883 kWh. 

Okay! So that’s where my 2.9 Megawatt-hours went!!

2016 will be the first full calendar year with the new solar addition. I’m estimating that this year will be our first complete net-zero year, maybe even a net-positive one.

What a great time to be alive!
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