Meter image
  • Send email to owner, designer
  • Site Homepage

    • Net Metering on a solar home
     by Matthew Lieber Buchman
    NET METERING?:
    There are essentially 3 types of utility meters:
    STANDARD METER
    This is the one with the little spinning dial we are all used to. It records all electricity usage in accumulated kilowatt-hours. This then appears on your bill. If you are running solar power into the gird, it can make the dial spin backwards, and this is exactly what some people do. In Homepower Magazine this has been dubbed "Guerilla Solar." (They have really cool teeshirts too.) Check it out at www.homepower.com.
    RATCHETED METER
    This is basically a standard meter with a ratchet built in so that you can't spin it backwards. Stingy.
    DUAL METER
    A dual meter, which Puget Power calls a 'net meter,' records separately the energy sent to the utility and the energy used from the utility. My meter actually records the accumulated kilowatt-hours in each direction since it was turned on.

    WHAT DOES THIS ALL MEAN?
    My solar panels convert sunlight into DC electricity which runs to my inverter. The inverter then decides, "Should I run their loads? Should I charge the batteries? Or is all that taken care of and I should send the excess to the utility and 'spin the meter backwards' so it is provided back to the utility for usage by other homes or businesses in the area?"
    When the PV electricity is insufficient for the loads, the inverter thinks, "Oh dear," and proceeds to take energy from the grid to meet the demand, thus running the meter "forward."

    Thirty-four states, last I heard, have net metering laws, but even those are not created equal. Washington state law allows the utility to keep any excess generated electricity as tallied on a yearly basis. If I use more kWh than I produce, I owe the utility money. If I produce more than I can use over the year they get to keep it. Puget Sound Energy notes that of the 18 "net metered" houses in their entire system of 1.2 million customers, no one has yet generated a surplus. I have hopes.

    RESULTS TO DATE:
    To consider: My wife and I both work out of the home on computers 6-10 hrs/day.
    date kWh
    to PSE    		 kWh
    from PSE    		 in period
    (+ = good)    		 life to date
    (+ = good)    		 production
    (actual)    		 usage
    (actual)    		 Notes
    2002
    Aug 24, 2002      inverter* turn-on
    1.8kw of panels*
    Aug 29      state electrical inspection
    Sep 400    net meter installed*
    Sep 4-30110130-20-20  7 hour blackout 9/8
    Oct '02187340-133-153   
    Nov '02242555-160-313   
    Dec '02256847-278-591  massive #'s of house guests
    2002 totals  -591-591   
    2003
    Jan '032881038-159-750   
    Feb '033501215-274-86555
    (18 days)    		-170
    (18 days)    		2/10: added meters for production tracking*
    Mar '034081407-408-99987-221 
    Apr '034841603-528-1119126-246 
    May '036021739-546-1137174-192 
    Jun '037351844-518-1109192-164 
    Jul '038911950-468-1059199-149 
    Aug '0310922064-411-1002241-187 
    Sep '0311782204-435-1026152-176 
    Oct '0312282404-585-117639-189 
    Nov '0312472619-781-137236-232 
    Dec '0312772889-1021-161234-274 
    2003 Totals10212042-1021-16121335-2356 
    2004 Totals11022055-953-25651448-2401 
    2005 Totals11121810-698-32631429-2127 
    date kWh
    to PSE    		 kWh
    from PSE    		 in period
    (+ = good)    		 life to date
    (+ = good)    		 production
    (actual)    		 usage
    (actual)    		 Notes
    * Check photos for images.

  • Send email to owner, designer
  • Site Homepage