A Net Zero Energy Year - Oct 18-Dec 15 2010

Picture# 001

Free heat bathes the Mill Creek NetZero Home’s east wall.

October 18 – Dec 15

    • Net Import: 1995 kWh
    • Net Export: 391 kWh
    • Total Production: 572 kWh
    • Total Consumption (imported + production – export): 2176 kWh

On the production side, we produced about 9.7 kWh/day when our annual expected daily average is 23 kWh/day.

I’m a bit concerned that we consumed such a boat load of electricity over the past two months. We used 37 kWh/day. Most of that is space heating energy. Our annual expected daily average use is 23 kWh/ day.

I still think we’re in the game. The months clustered around the winter solstice will understandably be when we consume the most and produce the least. Last year we pretty much stopped heating on February 12th, so even if we burn up a large deal of our energy budget by then, the good times will have arrived.

Whatever happens, there will be no denying the numbers.

Today’s readings (October 18 readings in parentheses):

  • bi-directional power meter (total import and export of electricity for the house):
    • import: 6155 kWh (4160 kWh)
    • export: 3327 kWh (2936 kWh)
  • inverters (cumulative production from each of two PV arrays):
    • fixed modules: 3881kWh (3683 kWh)
    • movable modules: 990 kWh (616 kWh)


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> We used 37 kWh/day. Most of that is space heating energy.

Define "most of that".

Are you talking ~60% of the 37kWh or closer to 80%? I'd be interested in specifics re: the amount of that 37 kWh allocated to heating. Granted... you might not have these hard numbers, but a guesstimate would do.

A thousand thank-yous.


During the summer we used 8 kWh per day. So that is close to our base load in winter. Add 3 kWh for the solar hot water that we´re not getting in the winter, and probably 11/37 kWh are non-heat. So 70% was space heating.


Conrad, Has the weather had an effect on your energy consumption? Have you had colder temperatures or fewer hours of sunlight than normal? Would these values be different from the numbers you factored into your projections?
Merry Christmas - Jim

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