Efficiency & Solar Array Improvements – case study in progress

We built a new energy efficient house with space for two businesses and noticed that our electric bills/use were much higher than we hoped for, about 1000 kwhrs/month annual average. The average in Wisconsin is about 690. In Spring 2011, we purchased a “kill-a-watt” meter and soon found that my 2004 desktop computer and a dehumidifier in the basement were using over 30% of the total power. I replaced the desktop with a laptop, used a box fan with a timer to control the humidity. We installed timers in other places and control strips to turn off phantom power when not used. These conservation measures dropped our monthly use about 300 khrs.

In December of 2011, we installed a 8kV solar array with net metering which encouraged us to further intensify our conservation awareness. With an electric hot water tank still requiring about 40% of the power we consume, our house/businesses are now about 35% carbon neutral and we’re contributing an average of 17 kwhr to the local grid each day. Installing a propane hot water heater on demand tank will come next.

Thus far, we are generating about twice the power we use during the day on average, but we still consume more power from the grid than we’d like to– especially on very overcast days and. of course, at night. We think we can reduce our night use by operating critical circuits from our 2400 watt back-power system for about 3-6 hours on nights when sun is predicted the next day.

Here is a fuller account thus far.
usage chart