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Testing PV's Amperage with Multimeter

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nschizzano

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2. 12v renogy 100 watt panels. I pop off the black plastic on the back to expose contacts of positive and negative. I am able collect a voltage reading with multimeter set to DC and V. It is usually around 19v in full sun. How ever when I attempt to gather Amperage data, my reader on displays 2 micro amps on both panels in full sun. Now I know it's more than thay because my MPPT says over 100 watts which would be over 7AMPs. Any one know how to measure Amps on my multimeter and solar panel? What am I doing wrong? I'm just aiming to learn everything in this field.

Using a pretty expensive Commercial Electric meter from Home Depot, about 8 years old.

I also have a new Klein meter I can use.
 
nschizzano said:
2. 12v renogy 100 watt panels. I pop off the black plastic on the back to expose contacts of positive and negative. I am able collect a voltage reading with multimeter set to DC and V. It is usually around 19v in full sun. How ever when I attempt to gather Amperage data, my reader on displays 2 micro amps on both panels in full sun. Now I know it's more than thay because my MPPT says over 100 watts which would be over 7AMPs. Any one know how to measure Amps on my multimeter and solar panel? What am I doing wrong? I'm just aiming to learn everything in this field.

Using a pretty expensive Commercial Electric meter from Home Depot, about 8 years old.

I also have a new Klein meter I can use.
Click to expand...
Wrong setting or blown fuse is the most likely cause. But you should see more like 21-24 open circuit.
 
nschizzano said:
2. 12v renogy 100 watt panels. I pop off the black plastic on the back to expose contacts of positive and negative. I am able collect a voltage reading with multimeter set to DC and V. It is usually around 19v in full sun. How ever when I attempt to gather Amperage data, my reader on displays 2 micro amps on both panels in full sun. Now I know it's more than thay because my MPPT says over 100 watts which would be over 7AMPs. Any one know how to measure Amps on my multimeter and solar panel? What am I doing wrong? I'm just aiming to learn everything in this field.
Click to expand...

If operating, this 19V is the operating voltage of the panel - somewhere between Voc and Vmp. If the panel is disconnected, then it's Voc.

nschizzano said:
Using a pretty expensive Commercial Electric meter from Home Depot, about 8 years old.

I also have a new Klein meter I can use.
Click to expand...

You must disconnect the panel from the system.

 
grizzzman said:
Wrong setting or blown fuse is the most likely cause. But you should see more like 21-24 open circuit.
Click to expand...
Well if it was a blown Fuse it wouldn't show any voltage? And it wouldn't show watts on my MPPT and charge my Batts? 21 - 24 VOLTS or AMPS? Yeah the back of the panel says max of 21v. I don't think it's full full sun when I check it so it only goes to 19.(×)

I'm also testing during a load, that'd be why. VMP reading of 19V
 
Last edited:
Blown fuse is in the current shunt section and would not affect voltage measurment. Did you use the right connections on the meter. Short circuit measurements don't indicate much. Half the panel could have bad cells and still indicate correct current. Two panels in parallel could blow a 10A fuse.
 
It sounds like you are applying the multimeter's amperage probes in parallel with the circuit. They don't work this way.

I've never found a use for a multimeter's amp function and I finally just bought one without that feature to get it out of my life.
 
sunshine_eggo said:
If operating, this 19V is the operating voltage of the panel - somewhere between Voc and Vmp. If the panel is disconnected, then it's Voc.



You must disconnect the panel from the system.

Click to expand...
Oh that's my problem the Commercial Electric meter I used does not have DC Amps. I did try changing the probe but I see exactly what to do now. Good one.

And yeah I was doing VPM not open.
 
nschizzano said:
Klein model is CL210 I don't think it has what we need. DC AMPS.
Click to expand...

Correct. AC amps only.

nschizzano said:
The Comercial Electric is model is MS8301B and I don't think it has the correct DC amps as well
Click to expand...


Page 05, leads must be in positions 7 and 8. Rotary switch one position to the right on A. You will probably have to use FUNC key to toggle between DC and AC

Page 18, 10A max for 2 minutes.

With the meter set correctly, you can follow the video I linked.
 
DC current is measured "inline" (in series) with the circuit with the typical probes of a multimeter.
You can't measure it in parallel across the terminals.

Be careful though, most meters I know have 10A capacity limit.
 
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