Solar Multimeter Testing

[RolfP]

Thanks for the lesson Paul, that's good news. So I should be able to test the voltage at the panel, at my connector in the boat along the coaming, and finally at the controller under the nav station. I should look for any drop in voltage greater than .28, or maybe a bit more? I connected to the + ad - at the controller at one point and got 17 volts. Maybe a bad connection? I'll bet that's it, it was around midnight when I was pulling wires for this. I'll get a new fuse, maybe a new multimeter, take off the overhead liner and do some testing. Tomorrow.

BTW, I only have the 2 50W panels for one controller, but I do have a second set of 50W panels and another controller for that set as well. That one still needs final wiring. I read that splitting the panels into multiple MPPT controllers provided more amps when the sun covered one set or the other. I have mine split between starboard and port. All 80' of wire is #10, but lots of MC4 connectors, another worry.

[Paul Elliott]

Yes, with multiple panels having more than one MPPT controller can help with shading problems.

When looking at small differences in voltage you have to make sure that the panel loading remains constant (or use a different measuring technique, which I can go over if you like). 17V is a perfectly reasonable voltage to see at the MPPT controller input, in fact it means the system is probably working fine. Here's the label from your panel:

See the number "Maximum Power Voltage 17.6V"? In extracting the maximum power from the panel the MPPT controller will draw current until the voltage drops to somewhere around that 17.6 V level. The exact "maximum power" voltage will depend on sun brightness, angle, shading, temperature, wire loss, battery charge level, etc.

This means that the voltage will be constantly varying a bit, making it hard to measure voltage drop as you are suggesting.

It's better to measure across your connectors if you suspect problems. Any measurable voltage is probably a bad thing. You can safely assume that if the wire isn't corroded or nicked it will perform as it should.

[RolfP]

Thanks for the advice and help. I got a new fuse, still couldn't read amps at the 10 amp setting, but the controllers are both showing charging and at one point one read "charged" while the other was blinking "charging". I shut off the shore power charger yesterday and today the Link read 14.5 volts or so and I have water and lead batteries so if I understand what I am reading here and there I'm getting charging done by the panels. Yeah. Now I have to move the boat somewhere were there is both sun AND warmth and probably on the hook a lot so then I'll begin to sort it all out.

Thanks again for the help, lessons, and explanations, it really has been helpful.




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[travellerw]

Originally Posted by RolfP

Thanks for the advice and help. I got a new fuse, still couldn't read amps at the 10 amp setting, but the controllers are both showing charging and at one point one read "charged" while the other was blinking "charging". I shut off the shore power charger yesterday and today the Link read 14.5 volts or so and I have water and lead batteries so if I understand what I am reading here and there I'm getting charging done by the panels. Yeah. Now I have to move the boat somewhere were there is both sun AND warmth and probably on the hook a lot so then I'll begin to sort it all out.

Thanks again for the help, lessons, and explanations, it really has been helpful.


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Glad to hear you have made some progress.. I hope to see you out there. How long until you are in Florida?

I'm back in Florida in early February and bound for Bahamas in late March.

[RolfP]

I hope to do something like that timing .


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[ErikFinn]

Originally Posted by Canibul

OR you could do something that you will appreciate later and buy a clamp meter.

I have my search tool list open and came across this thread, and trying to search anything about how to test solar panels. I would like to be able to test my 8 panels easily and quickly, without having to disconnect wires and batteries and so forth.. Being electrically challenged I would like to be able to do this quickly, easily and reliably..
I have a Fluke multimeter but considering buying a clamp meter. Would panel testing be very simple and easy with a clamp meter? Anyone?
Cheers,
Erik

[socaldmax]

Originally Posted by ErikFinn

I have my search tool list open and came across this thread, and trying to search anything about how to test solar panels. I would like to be able to test my 8 panels easily and quickly, without having to disconnect wires and batteries and so forth.. Being electrically challenged I would like to be able to do this quickly, easily and reliably..
I have a Fluke multimeter but considering buying a clamp meter. Would panel testing be very simple and easy with a clamp meter? Anyone?
Cheers,
Erik

No, I don't think a clamp meter will make it any easier to test solar panel output current.

Just aim your panel at the sun, set it in current mode (make sure it's capable of more current than your panel puts out) and stick your meter probes into the ends of the cables, hopefully making good contact. You should be able to see roughly 75% or more of rated output depending on the sun's position. More importantly, you should see consistent output from panel to panel, assuming the sunlight you're getting hasn't changed.

I once tested 16 used panels like this and it only took a short while, most time was spent moving the panels around after testing.

[hellosailor]

Erik, if I wanted to test 8 panels and ignore any complications form the system wiring...I'd disconnect each panel and test each one at a time. If each is putting out a similar full voltage (for whatever they are rated at) I'd just read amperage from the system as a whole, unless there was some reason to think one was defective. (Cracked, water intrusion, etc.)


Of course if each panel was rated, say, 100 watts? You could just get a 100W bulb of an appropriate voltage (12 v nominal system?) and see if each panel lights it up. Sometimes, numbers aren't important, and a quick test light will do the job well enough.

[ErikFinn]

Thank you for kind advice guys.
No wonder I couldn't find youtube videos about using clamp meter for testing panels..

[Paul Elliott]

But clamp meters are wonderful for in-use panel testing. Clamp meters also can measure higher currents than the typical multimeter. If your panels put out more than the multimeter can handle then a clamp meter is a great thing to have.

To measure short-circuit current from a panel, first disconnect it from any batteries, then connect a wire across the output terminals. That wire is your short-circuit. Put the clamp meter around the wire and measure. Or, instead of the wire, use your (high-enough current capable) multimeter probes to connect to the panel output terminals.

[TheThunderbird]

Originally Posted by Canibul

Put another way, there has to be a complete circuit and the meter is part of that complete circuit.

OR you could do something that you will appreciate later and buy a clamp meter.

Clamps are only for VAC circuits

[Paul Elliott]

Originally Posted by TheThunderbird

Clamps are only for VAC circuits

No, there are DC/AC clamp-meters -- I've got a couple myself. They use Hall-effect sensors. Here are the ones I currently have:

($360) - Fluke 376 Clamp Meter [corrected link and price]

($45) - Sears.com

[socaldmax]

Originally Posted by Paul Elliott

But clamp meters are wonderful for in-use panel testing. Clamp meters also can measure higher currents than the typical multimeter. If your panels put out more than the multimeter can handle then a clamp meter is a great thing to have.

To measure short-circuit current from a panel, first disconnect it from any batteries, then connect a wire across the output terminals. That wire is your short-circuit. Put the clamp meter around the wire and measure. Or, instead of the wire, use your (high-enough current capable) multimeter probes to connect to the panel output terminals.

At which point you're directly measuring the current instead of using the clamp meter.

My hesitation to recommend clamp meters are twofold:

1. The readings you get (especially DC) can be affected by the distance from the wire to the Hall Effect sensor, and it might not be obvious where in the clamp the sensor is located. This might not be true of all meters, but I think I remember seeing inconclusive readings on a friend's and I haven't trusted them for DC since.

2. What people are tempted to do is simply connect the + and - solar panel leads together with nothing in between. This bothers me because if you're pushing a decent amount of current, a poor connection could overheat and melt the connector. With a direct reading, the multimeter is in the middle with it's 10A fuse.

Those are just my thoughts on it, they may not be valid to everyone.

[TheThunderbird]

[QUOTE=Paul Elliott;2040392]No, there are DC/AC clamp-meters -- I've got a couple myself. They use Hall-effect sensors. Here are the ones I currently have:

($270) - Amazon.com: Fluke 325 40/400A AC/DC, 600V AC/DC TRMS Clamp Meter w/ Frequency, Temp, & Capacitance Measurements: Home Improvement

Paul, I'd like to be wrong, 'cos they asked me 500+eur for a DC Ammeter... sorry.

Here is your Fluke:

"Measurement capability
400 A ac current measurement

600 V ac and dc voltage measurement

True-rms ac voltage and current for accurate measurements on non-linear signals

Resistance measurement up to 4 kΩ with continuity detection"

No DC A reading.... the current must go thru the meter, when DC

[HappyMdRSailor]

Originally Posted by TheThunderbird

Clamps are only for VAC circuits

Nope... Definitely DC clammmpers exist....

Originally Posted by socaldmax

At which point you're directly measuring the current instead of using the clamp meter.

My hesitation to recommend clamp meters are twofold:

1. The readings you get (especially DC) can be affected by the distance from the wire to the Hall Effect sensor, and it might not be obvious where in the clamp the sensor is located. This might not be true of all meters, but I think I remember seeing inconclusive readings on a friend's and I haven't trusted them for DC since.

2. What people are tempted to do is simply connect the + and - solar panel leads together with nothing in between. This bothers me because if you're pushing a decent amount of current, a poor connection could overheat and melt the connector. With a direct reading, the multimeter is in the middle with it's 10A fuse.

Those are just my thoughts on it, they may not be valid to everyone.

maxman... They are actually fairly accurate ....

[QUOTE=TheThunderbird;2040469]

Originally Posted by Paul Elliott

No, there are DC/AC clamp-meters -- I've got a couple myself. They use Hall-effect sensors. Here are the ones I currently have:

($270) - Amazon.com: Fluke 325 40/400A AC/DC, 600V AC/DC TRMS Clamp Meter w/ Frequency, Temp, & Capacitance Measurements: Home Improvement

Paul, I'd like to be wrong, 'cos they asked me 500+eur for a DC Ammeter... sorry.

Here is your Fluke:

"Measurement capability
400 A ac current measurement

600 V ac and dc voltage measurement

True-rms ac voltage and current for accurate measurements on non-linear signals

Resistance measurement up to 4 kΩ with continuity detection"

No DC A reading.... the current must go thru the meter, when DC

Tbird...

I have 2 or 3... This is the last one I bought... CHEAP and feels like a Fluke using it...
http://www.amazon.com/gp/product/B00...rch_detailpage