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Old 05-24-15, 11:08 AM   #1
gtojohn
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Default How much power does your gridtie inverter draw when the sun is down?

I added a Mieo power meter to my enphase pv array. I'm doing this in lieu of the enphase envoy. This gives me a remote heads up display of output and tracks monthly output. Its only been installed for a day but I noticed last night I had a draw of 90 watts. This is for only 6 enphase inverters. There's a slight chance the inductive clamp was picking power from another circuit but this draw went all night and my other consumption was around 400 watts. I'll try it again tonight with the breaker off. My thoughts if this is correct would be to put a timer on the circuit to save on my overnight draw. Amazon.com : MIEO HA102 Wireless Electricity Monitor for Single Phase System with 1 CT4 Current Sensor : Patio, Lawn & Garden

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Old 05-24-15, 01:31 PM   #2
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It could be sensing the reactive power.
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Old 05-24-15, 02:12 PM   #3
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Or the inverters use 15 watts each in standby. Seems like a lot for solid state electronics.
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Old 05-24-15, 02:41 PM   #4
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I found this on an AZ solar forum:
"I wonder if it's possible that the PV meter is reading "reactive" power?
While the actual night-time power draw of the Enphase units is low (30mW/unit or 0.3w for 10), they do "draw" about 100 mA/inverter. This would be about 1A or 240VA for 10 inverters."
Perhaps it is just my power meter. The math for 6 panels would be 144va which I'm not seeing. Puzzling...
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Old 05-28-15, 08:07 AM   #5
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In my grid-tie electric agreement, I am forced to have a separate {smart} meter for just my solar array's. The meter reads backfed power so they can bill it to me at retail, versus they pay for electricity at retail plus.

Everything related to our two solar arrays goes through this meter before it can be fed into my house. The meter reads the energy from and to 6 Enphase inverters plus the Enphase Envoy, one Sunny Boy 5000 inverter and of course, it counts the three midnite solar surge suppressors in the system {each has two blue leds on at all times}. All of that said, I read my meter every night that I am home. Since 12/17/13, or 892 days if you prefer, my meter says there has been 73 kWh's backfed by this system.

Was that 90 watt draw you mentioned a total amount for the entire night, or was it 90 watts x however many hours? Even at 90 watts for an entire day, I count that to equal 80,280 watts over the same amount of days. Divided by 1,000, it would come out to 80.28 kWh if my math is correct. That is still considerably more than I would expect from your array.
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Old 05-28-15, 08:48 AM   #6
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Because its an inductive clamp probe its truly Volt Amps, which is how watts are calculate. However because it doesn't really measure volts, you select it, there might be an opening for error. That being said, my reading is 90 VA per hour overnight. If each inverter uses .0625 amps at 240volts it will use 15 watts in standby. I'm not sure it it really is but thats my math. I will build a adapter for my killawatt meter to install between my pv and breaker panel when I get the chance and settle this. The panels more than mike up for this during the day, but 90 watts an hour all night can add up.
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Old 06-03-15, 10:19 AM   #7
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Just shut off all the breakers except PV feed. My power monitor showed 80 watts so 13.33 watts per inverter or .055 amps each per hour all night. My plan is to install a hotwater heater timer between the breaker and pv.
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Old 06-05-15, 06:27 PM   #8
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My Solaredge SE3000A-US inverter uses 4 watts in night mode. It seems to use about that same amount during its 5 minute 'powering up/grid stability check' phase when turning on as well as when it is active and the sun is going down before it goes into night mode. So just about 100wh daily. I'm okay with this level of consumption. My solar installer tests multiple different systems and when I look at his eGauge, it seems some might be pulling 10+ watts in standby overnight, which for a small system I'd probably be less satisfied with.

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