The Revenge of the Negawatts


            After a year and a half of watching our electric production from our Solar PV system we became much more conscious of our consumption. We had been pretty conservative before in terms of what we used from the begining. We built our Passive Solar house in 2000 to what was, at the time, high levels of insulation.  We added a solar hot water system that helps heat the water that goes into our radiant floor system for winter heat as well as domestic hot water. We bought efficient Energy Star appliances and all Compact fluorescent bulbs through out the house.  We have a wood stove to do most of our heating  and don’t own a clothes dryer or any air-conditioning.

The addition of the PV system, that was sized to produce as much electricity as we use, added a new level of attention to our energy use.  In 2011 we produced 55 Kwh more than we used.   That was to close for comfort. Game on.

We got a kill-A-Watt meter and plugged everything into it we could.  That inspired us to put in outlet strips we could turn off on our TV and DVD player, phone chargers and our computer and modem. The ghost power drains were the easy targets. We also got a great tip from fellow blogger Amy Musser in her blog, It’s not the heat, it’s the stupidity. We now keep the daylight basement area of our house that we have to dehumidify June-August closed up rather than opening it at night to cool it down.  The night air is generally more humid and opening up just meant you lost all the gains you had made the day before and needed to start over each day with a fresh batch of soggy air.  We now empty our dehumidifier half as much and the bermed basement room stays a dry 73-78 degrees, comfortable without AC.  The other energy hog was our water use that I discussed in a previous blog What?  The Water?  Basically pumping water is a heavy lift and pumping less water is a big energy saver. We added cisterns and turned off our water feature pump.

That was the strategy what are the results? The Tables below tell the story.  Production was really close, as we produced 7Kwh less in 2012 than 2011. We used 666 fewer Kwh (Negawatts) of electricity over the 8-month period in 2012 than in 2011. When adjusted for our absence during a month vacation in February 2012, it is a 547kwh reduction. That is about a 20% reduction in energy use from those measures. In dollar terms at an average .12 cents per Kwh that is $65.64 savings for the 8-month period.

So for 2012 our energy measures produced 547 negawatts and have us comfortably positive for renewable electricity.  But we still have the 150 gallons a year of Propane a year to deal with.

 Production from Solar PV

2012            Kwh                          2011            Kwh                       

8/27/12            348                        8/26/11            388

 7/27/12            364                        7/28/11            365

 6/27/12            416                        6/29/11            456

 5/29/12            372                        5/26/11            372

 4/26/12            417                        4/27/11            391

 3/26/12            344                        3/28/11            326

 2/24/12            280                        2/24/11            297

 1/26/12            236                        1/27/11            189

 Total                        2777                                                2784

 Difference           -7 Kwh  produced 2012                                                                       

 Use from Grid 

   2012             Kwh                             2011          Kwh  

 8/27/12            338                        8/25/11            435

 7/27/12            364                        7/27/11            418

 6/27/12            351                        6/28/11            495

 5/29/12            280                        5/25/11            309

 4/26/12            250                        4/26/11            293

 3/26/12            193                        3/25/11            286

 2/24/12            99(vacation)            2/23/11            218

 1/26/12            188                        1/26/11            275

Total Use         2063                                            2729           


Difference-            666Kwh less consumption in  2012     


Production Vs Use

2012= +714                                              2011= +55            

2012 Adjusted for Vacation= +595kwh