First let me say thanks to everyone who replied in my previous thread 'Need help in buying a meter. So yesterday I bought a multimeter.As some of you may remember a neighbour of mine gave me a brand new still in the box 40W solar panel. Here is the specs of the 40W solar panel.Up to 40WattsOpen circuit volt. 21.5vMax power volts. 17.1vShort circuit current. 2.3AToday a few minutes ago 'noon time' I tested my solar panel and here is what I got.Volts: 10.07 Amps: 1.68 Question: Does this sound right? Is the volts/amps enough to change a 12v battery?Thanks

Nope. You need at least 13.5VDC to charge a battery. Sounds like your free by has some bad cells.

Try aiming directly at the sun, mid day, when measuring. You should meter 17 to 21V and the Amperage sounds a bit light, should be seeing over 2 amps, if your battery is low in state of charge. Try again, in direct sunlight, mid day, around noon, and get back to us.In the future, get in the habit of listing the number first, then the unit of measure.

Ok? Question on my process. I connected the multimeter probes directly to the controller output, is that correct? Will try again tomorrow got some errands to do.Thanks again for the replies.

icanon wrote: I connected the multimeter probes directly to the controller output, is that correct? Solar panels don't have controllers on them. If you mean that box on the back, that's simply a junction.I agree, it sounds like a defective panel, provided your meter was set to the proper DC voltage range.

2oldman wrote:icanon wrote: I connected the multimeter probes directly to the controller output, is that correct? Solar panels don't have controllers on them. If you mean that box on the back, that's simply a junction.I agree, it sounds like a defective panel, provided your meter was set to the proper DC voltage range.The part I was talking about says on it, 7amps Solar Controller, so I guess it's called a controller. Will take photos of process tomorrow.

Part 2 Need help in buying a meter. | Good Sam Community

24 Replies

red31
Explorer
Sep 28, 2015
Do not connect the controller to the panel unless it is connected to a battery.

Test a panel without being connected to anything.
MEXICOWANDERER
Explorer
Sep 28, 2015
Impossible to defeat full sun short-circuit amperage test of panel. Easy to do and infallible. Clear skies wait till noon and short that sucker. But beware of Ching Chong meter test lead resistance. Best to use an inductive meter or Oldaker Test Leads on a conventional meter.
icanon
Explorer
Sep 28, 2015
Update:

Brought it back without bill they offered to exchange but not money back as I had no bill. Asked if I can exchange and pay the difference on an another size they accepted and I got a 75W 4.3a solar panel. Needless to say the 75w was on sale at half off.

Waiting to test it the weather is very cloudy and light rain.
time2roll
Nomad
Sep 27, 2015
Remove the controller if you want to test the solar panel.
2oldman
Explorer II
Sep 27, 2015
icanon wrote:
hope the photos helped?

Will try to bring to store without bill as it was given to me and I checked their website it still offered for sale. Cross my fingers.
Immensely. Take the money and run.
icanon
Explorer
Sep 27, 2015
Thanks 2oldman.
Hope the photos helped?

You won't believe just what happened? Wife tells she smell burnt plastic and guess what the 'controller' back side melted. Will try to bring to store without bill as it was given to me and I checked their website it still offered for sale. Cross my fingers.
2oldman
Explorer II
Sep 27, 2015
Yes, that does look like a separate controller. What I would do at this point is connect it to a battery and take another voltage reading. Sometimes open circuit isn't the best way to measure.

All things considered, a 40w panel isn't going to be of much good beyond maintenance charging.
icanon
Explorer
Sep 27, 2015
Here are some pics I took late today actually 4:00pm
Got nearly the same results.
2oldman
Explorer II
Sep 27, 2015
icanon wrote:
.. says on it, 7amps Solar Controller, so I guess it's called a controller.
That would be a first for me anyway! Pictures would help, thanks.
icanon
Explorer
Sep 27, 2015
2oldman wrote:
icanon wrote:
I connected the multimeter probes directly to the controller output, is that correct?
Solar panels don't have controllers on them. If you mean that box on the back, that's simply a junction.

I agree, it sounds like a defective panel, provided your meter was set to the proper DC voltage range.

The part I was talking about says on it, 7amps Solar Controller, so I guess it's called a controller. Will take photos of process tomorrow.

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Part 2 Need help in buying a meter.

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