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diy solar

What is wrong here?

bombattah

New Member
Joined
Oct 5, 2020
Messages
9
PICWRONG.jpg

Hi guys,

To explain this picture.. I have 3 x 295w panels half shaded when i took the picture, connected in parallel to a grid tie inverter. The AC output of the grid tie inverter claim to be over 330W ( 2.855A X ~120V ), but the meter from panels only register 244.1W in..

Do i have the worlds most efficient grid tie inverter ( ~145% efficiency? ) Whats faulty with this picture? I cant make sense of these numbers... Yes pictures where taken at the same time... Nothing but the grid tie inverter output is connected to this "kill a watt" meter.

Best regards,
 
The inverter is plugged into the watt meter, ie this is sole point where the inverter is tied to the premises wiring? There isn't a separate in and out for a grid tied inverter. While there might be separate wiring connection points they are internally joined for a proper grid tied device.
 
The only thing I can come up with is your meters aren't all that good and can't accurately measure the watts.

If the DC side has a lot of noise on it the watt meter may not be registering the power contained in that high frequency noise. The AC side meter may not handle distorted waveforms (power factor, crest load, high frequency noise etc). This isn't necessarily why you are seeing it, they could simply have terrible calibration, but it is a possibility.
 
The only thing I can come up with is your meters aren't all that good and can't accurately measure the watts.

If the DC side has a lot of noise on it the watt meter may not be registering the power contained in that high frequency noise. The AC side meter may not handle distorted waveforms (power factor, crest load, high frequency noise etc). This isn't necessarily why you are seeing it, they could simply have terrible calibration, but it is a possibility.
Thanks!

I agree, one or two of these meters are probably faulty. Wish i knew what to replace for more accurate readings.

For one moment i was thinking maybe the inverter just pulls 330W to do its thing.
 
Can your clamp meter do DC amps? Comparing that, as well as a separate voltage check would be close enough to tell if the DC watt meter is within cooee.
 
Poor meters. Good enough, but will never agree with each other.
 
Maybe the waveform isn't all that pure out of the inverter than what the ac meter is expecting to read?
Very spikey?
edit: as gnubie has already said
 
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