No... resistance will be proportional to wire length for same type of wire. Longer=more resistance = lower current for given voltage.
Current and voltage : positive correlation?
- Thread starter skyman
- Start date
Yes I have Clamp meter, please correct me if I am wrong :
Clamp meters offer a contactless way of measuring current but it can’t measure voltage in a contactless way.
hwy17
Anti-Solar Enthusiast
Correct. But the most commmon form of clamp meter is a Current Transformer that only works with AC current. I think DC requires hall effect. I don't own a DC clamp meter myself.
seneysolar
Solar Addict
Ok, now we have the question.
Looking at the picture it would indicate the meter is showing INCOMING voltage and INCOMING current.
Example: look at line 1, 564.2 x 4.62 = 2.6kw of incoming power from the panels.
Current (amps) will be close to the same if both MPPT channels are only 1 string of the same panels. So yes, it looks correct- Voltage is higher with more panels in series, amperage is the same being only 1 string. Total power is more because VOLTS x AMPS = WATTS
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You're correct that a lot of clamp meters only measure AC current. That said, a number of clamp meters now measure both AC and DC current via a clamp. I use a UNI-T UT210D (great price at ~$60) and Fluke 365 (Fluke priced) and they both measure AC and DC amps via the clamp. I recommend both but the UNI-T product is a compact unit at a great price that goes down to milliamps (win-win-win).
Edit: use care selecting a UNI-T 210: sub-models A, B&C only measure AC amps, the D&E sub-models measure AC and DC amps with a capacity of 200 (D) or 100 (E) amps.
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hwy17
Anti-Solar Enthusiast
Yeah I've got my eye on the 362 but just hesitant cause I don't know if I want true RMS voltage. Probably don't need it.
@All
Thank you for the insightful tips.
However there is still a missing piece of puzzle and nobody mentioned it :
A current leakage somewhere in the string ( a damaged MC4 or Panel itself ) could reduce the whole current transmitted to the inverter
Isn’t this a mechanistically plausible cause ?
Thank you for the insightful tips.
However there is still a missing piece of puzzle and nobody mentioned it :
A current leakage somewhere in the string ( a damaged MC4 or Panel itself ) could reduce the whole current transmitted to the inverter
Isn’t this a mechanistically plausible cause ?
I would suspect the inverter would generate an alarm if a leakage occurred on the PV side - see this info re my Solis inverter...
solis-service.solisinverters.com
I-Leak-Pro
If you wish to download this article as a PDF, please scroll to the bottom of the page or click HERE. Share this article: Share via Email I-Leak-Pro or Leakage current Background Leakage current failure: faults a...
solis-service.solisinverters.com
The difference in power is minimal (less than 6%) - take into account different wire lengths, different resistances of connections, accuracy of the inverter to measure and report the current and, as someone said earlier, differences in the actual panels performance.
PV panels are typically rated for their quoted power -0% to +5% - so not all will be equal.
IMHO this is a non-issue.
PV panels are typically rated for their quoted power -0% to +5% - so not all will be equal.
IMHO this is a non-issue.
@jimf909 @hwy17
I just found out that my digital clamp Meter measures only AC current !!
I am looking online for a new clamp meter that can measure DC current as well, but before I buy one I want to ask you if you know a clamp meter that can also measure DC voltage in a contactless way :
I want to measure DC voltage of every panel without breaking the circuit, i hope that can be achieved :
Suppose you have 10 panels and there is a clamp voltage meter that can show you the voltage of each panel within the string, so with 10 panels I expect to see the voltage increases after every successive panel
Do you know of any clamp meter that can do this ?
hwy17
Anti-Solar Enthusiast
No, as far as I am aware, that does not exist.
Agreed. There are NCVT devices that test for the presence of AC voltage but they don't measure it. And not DC.
Will be happy to be proven wrong.
Well i am no longer sure that such thing doesn’t exist :
Look at this one
Extech 381676A Pen Digital Multimeter w/ Voltage Detector
The Extech 381676A Pen Digital Multimeter features an integrated non-contact voltage detector, retractable tip and large 2000-count high-contrast LCD. It uses an autorange function along with data hold, range hold, and maximum hold features to test AC circuits, digital circuits, and more. The...
www.specialized.net
