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Friday, March 16, 2012

100KWH of production today!

At about 10AM the APS guy stepped from his white pickup truck and donned his hard hat.  He started his inspection by removing the production meter and inspecting inside the meter box.  He read the back-feed breaker rating of 22KW or kIAC (peak inrush amps current).  He tagged or sealed the production meter and placed a shiny golden padlock on the disconnect switch door -- keep in mind that inside this box both sides of the switch are HOT.  Salt River Solar and Wind folks, two electricians and Sheri Soto, showed up just before 10:30AM.  They asked the APS technician if he wanted the breaker panel cover removed -- he didn't.  They moved behind the fence gate and inspected the combiner panel.  The APS inspector and the two SRSW electricians went up the ladder to the roof.  My pastor and friend Michael Page showed up and we also toured the PV farm on the roof.  When we came down everyone was ready to see it run, now about 11AM.  The start-up sequence was disconnect switch to ON, PV back-feed 125-AMP breaker to ON, combiner panel three 40-AMP breakers to ON, SMA Sunny Boy 7000US inverter disconnect switches #1, #2, and #3 rotated to vertical ON.  The inverters came up at about 5100 watts apiece and in just a few minutes we saw all of them above 5500 watts.  The production meter disk spun around about every 2 seconds.

I came in and set one AC unit to 70 degrees and FAN ON.  This was to apply a fairly constant load inside the house, to get an idea what we will be using on most days as the temperatures climb.

Here are the readings from the APS digital smart meter and the mechanical production meter.  Note that the production mechanical meter started the day with 4 kwh from prior testing.  Note that the smart digital meter has only been installed for 3 days and that the inbound readings did not change until sundown when our production stopped.

03-16-12 11:44
24 kwh on production meter (started up with 4 on this meter)
80 kwh inbound total 17 kwh inbound peak 0 demand
14 kwh outbound total 0 kwh outbound peak 0 demand

03-16-12 14:44
74 kwh on production meter
80 kwh inbound total 17 kwh inbound peak 0 demand
56kwh outbound total 40 kwh outbound peak 15.08 demand out

03-16-12 15:46
89 kwh on production meter
80 kwh inbound total 17 kwh inbound peak 0 demand
69 kwh outbound total 52 kwh outbound peak 15.08 demand out

03-16-12 16:44
99 kwh on production meter
80 kwh inbound total 17 kwh inbound peak 0 demand
76 kwh outbound total 59 kwh outbound peak 15.08 demand out

03-16-12 18:30 (shutdown was immediate after the sun went below the horizon)
104 kwh on production meter
81 kwh inbound total 18 kwh inbound peak .87 demand
78 kwh outbound total 61 kwh outbound peak 15.08 demand out

03-16-12 19:14 (after peak period ended)
104 kwh on production meter
82kwh inbound total 18 kwh inbound peak 1.60 demand
78 kwh outbound total 61 kwh outbound peak 15.08 demand out

Questions I have:  Why did the demand numbers stay at zero for the first three days since this new digital smart meter was installed, and then start recording both directions (in and out)?

Answers I have:  The inverters  kept producing until they reached 2 watts.  Then they said WAITING and kept sampling the PV input (clicking of relays) until the PV input voltage went below 220vdc.  The production meter had 4 kwh on it from my previous testing and playing around... so the total production for the day ended on 104 for an even 100 KWH produced since our 11AM start up.  My AC was using a pretty consistent 3 kwh per hour during the day.  Not much else was on until after dark, then lights and a TV were on.  At the end of the day the SMA inverters reported 65 lbs. of CO2 savings each -- based on replacing fossil fueled generation for the same 33.5 kwh on each inverter.  195 lbs. of CO2 is a lot for 7.5 hours.  We produced about one dollar per hour based on the winter rates.  We put 78% of that into the power grid, gaining a credit of about 78 cents per hour.

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