I just bought some used IQ8M's. With 8 panels and inverters connected in one string, the night time current draw is .56 amps on one leg. This was measured with a Fluke clamp-on ammeter. They function normally during the day. Is this typical? It seems like a lot of wasted power. I have not connected them to an IQ Gateway yet, but one is on order; however from what I read that is only needed to change grid parameters and for monitoring.
Enphase IQ8 night-time power consumption
- Thread starter lapsmith
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sunshine_eggo
Victron's little biatch
Probably not an accurate measurement. It depends on the error of the fluke, which depends on the measurement scale range and the meter error, especially in the significant digit rating.
What Fluke?
I created an issue with my neighbor where it appeared his new A/C unit had a steady 80W draw based on a ~.35A @ 240V measurement with a Klein CL800. 80W was MAJOR for his system and would have represented about 25% of his total consumption w/o running the A/C.
When I moved to the DC side, the draw was 7W to power the electronics.
When I ran the error numbers, I discovered the meter was essentially useless for measuring low current AC draw.
Example:
Fluke 302 + CAT III Digital Clamp Meter | Fluke
The Fluke 302 + is a rugged, easy-to-use digital clamp meter with CAT IV 300 V/CAT III 600 V safety rating.
www.fluke.com
States a 1.8%±5 accuracy.
This means a 1.8% error in on the total scale, PLUS a ±5 variation in the least significant digit.
That units lists a 400.0A range.
This means that the total range can vary by 1.8% as well as an additional ±0.5A, so if you're trying to measure a current small current, you're going to get a ±0.5A or 1A total error. This error is larger than the value measured. It's basically worthless.
To get a truly accurate measurement of <1A, you'd need something like this:
Fluke 368 FC Leakage Current Clamp Meter | Fluke
The Fluke 368 FC true-rms leakage current clamp meter helps you measure small problems before they become large problems, all without taking equipment off line.
www.fluke.com
On the 3A scale, it would be accurate to ±1% and ±.005A
MikeInKingman
New Member
337. Specs say accuracy is 2% - 5 count (whatever that means) @60Hz. Range is 999A. So accuracy is only 2 amps? Now I can see why you say not an accurate measurement.
Today I tried the meter below. I have no idea what the accuracy is, but it appears to take into account power factor. Last night, it was showing that all 8 panels were only drawing 5 watts, while the current was still .6 amps. (The picture was taken in the morning with the sun very low, thus the higher power).
So it looks like everything is working as it should. Thanks!
sunshine_eggo
Victron's little biatch
The "5" means ± "5" in the last digit displayed, so in addition to the 1.8%, it will have another ±0.5A.
My neighbor and I chased this down for half an hour. Learned that compressors have a ~40W heater that keep the oil from getting too cold, so I thought it might be that, but it was like 70°F out, so it didn't make sense.
My neighbor and I chased this down for half an hour. Learned that compressors have a ~40W heater that keep the oil from getting too cold, so I thought it might be that, but it was like 70°F out, so it didn't make sense.
Got it, thanks. I never knew AC compressors have a heater. Makes sense if it is a heat pump which operates in cold weather. Wonder why one would care if the oil gets cold, if it never runs. Unless it was a commercial unit.
sunshine_eggo
Victron's little biatch
I've forgotten some details since this was a couple years ago. After a little brush up...
It has less to do with the oil (though maintaining viscosity is part of it) than it has to do with keeping the temperature above the refrigerant's boiling point to prevent the refrigerant from condensing in the compressor. The compressor is designed to pump vapor, not liquid.
Here's a blurb from a random Lennox manual:
Crankcase Heater (HR1) and Crankcase ThermostatSwitch (S40)
The reference models are equipped with a 70 watt, belly band type crankcase heater. HR1 prevents liquid from accumulating in the compressor. HR1 is controlled by a thermostat located on the liquid line. When liquid line temperature drops below 50° F the thermostat closes energizing HR1. The thermostat will open, de−energizing HR1 once liquid line temperature reaches 70° F .
@Supervstech can probably elaborate.
Solar Guppy
Red Cobra Guppy
Read up about reactive vs real power for AC circuits. A hand held can't using just current measure real power.
A little off topic, but I learned something new. Although after a bit of googling, I'm not sure why more residential HVAC systems don't have crank case heaters. I personally never use the AC until the outside temps are in the upper 80's. I've also never had a unit with CCH in any of my homes.
There was some good discussion here.
Good article. Are micro inverters similar to my hybrid inverter which has lots of inductance and capacitance? If so, then would they tend to cancel each other out, as far as reactive power?
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