Help for the electrically challenged

Submitted: Sunday, May 09, 2004 at 11:42
ThreadID: 12713 Views:1906 Replies:6 FollowUps:3
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Hello all, I could use some help in checking the output of my solar panel. Bought a Dick Smith multi-tester some time back. For the first time ever, I decided to read the instructions before using it. The instructions gave no indication whatsoever about how to use the thing, just a brief description of the functional switch.
My solar panel states on the back
Nominal rated power 60 watts
Voltage at peak power 14 volts
Current at peak power 4.3 amps
Open circuit voltage 20 Volts
Short circuit 5.3 amps
Now I just put the multi-tester on the panel, in the garage (no direct sunlight) and got a reading of .86 with the pointer on the 20 and 4.7 with the pointer on the 200.
Tested it yesterday in full sun and got a reading of 1.34 with pointer on 20 and 6.3 with the pointer on 200
I am using the segment which is identified by the symbol V then a straight line with 3 dots below it
Is there a shot circuit in the panel, is the multi-tester malfunctioning or is it the dill trying to operate the thing ?
Thank you in advance
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Reply By: Bonz (Vic) - Sunday, May 09, 2004 at 14:32

Sunday, May 09, 2004 at 14:32
The straight line with the dots below it means DC, direct current, and on the 20 scale I assume 1.34 is on a scale of 0-10 seeing that you also got a reading of 6.3. If thats the case then its 1.34*2=5.36 volts which is nowhere near the stated output of 14 volts. I assume its not a digital tester> more info would be handy.
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AnswerID: 57841

Reply By: navaraman - Sunday, May 09, 2004 at 17:18

Sunday, May 09, 2004 at 17:18
As Bonz said you are meauring DC volts. If it's an analogue multi-meter and it sounds like it is it may need zeroing first. You may also get strange readings if there is no load on the solar panel. can you hook it up to a fridge or something and check it again, open circuit voltages can be all over the place..
AnswerID: 57859

Follow Up By: Janset - Sunday, May 09, 2004 at 19:07

Sunday, May 09, 2004 at 19:07
Hi there

The simplest way out of this and to avoid misunderstanding is for you to take the multimeter and your vehicle to a friendly Auto sparky and get him to demonstrate it on the 12 volt system on your vehicle.

He can do that in a couple of minutes, and you have the benefit of asking questions at the same time.

That is how I did it (years ago). Incidentally, a digital multimeter is the only real way to test solar panels as they give you a definitive reading as opposed to a needle (just on or off) a particular line on a scale, one scale amongst a number. No contest there. :-)

FollowupID: 319625

Reply By: Member - Dave (Pilbara) - Sunday, May 09, 2004 at 19:46

Sunday, May 09, 2004 at 19:46
Chris, You get what you pay for. If its the normal mass produced multi meter the accuracy would be very variable(read hugely inaccurate). Use it as a rough indication only. Also an analog meter puts a small resistance into the circuit due to the coil having to drive the needle. Cheap meters do not compensate for this so the reading is further deteriated. A digital meter would generally be more accurate. Solor panel specs are very subjective and are obtained in the lab with best possable conditions. Things like temperature and angle the sun strikes the panel have a huge effect.
have a look around and do a google on solar panels there is a lot of good info out there.
AnswerID: 57883

Reply By: Kev - (Cairns,QLD) - Sunday, May 09, 2004 at 21:33

Sunday, May 09, 2004 at 21:33
Dick Smiths sell a digital multimeter for under $20, not the best quality but i use one all the time along with my Fluke meter and have no troubles. (rated at 240v but not recomended)
AnswerID: 57901

Follow Up By: Gerk - Sunday, May 09, 2004 at 22:34

Sunday, May 09, 2004 at 22:34
Do you have a regulator across the panel terminals as this will read little or no volts without a load ie battery as the load. If you want to test the panel only make sure there is no reg in the circuit. cheers.
FollowupID: 319661

Reply By: daddy - Monday, May 10, 2004 at 07:32

Monday, May 10, 2004 at 07:32
Thanks for the responses. In reply to some of the questions.......
the multi-tester is digital
there is a regulator on the panel
the panel wasn't under load when tested

The instructions don't even give an indication of where to to connect the probes to the multi-tester for differing tests, for example there are two probes and three possible ports in the unit to plug into. Which two do I use to test amps ?
If some one would be so kind as to describe step by step how they would test the amperage on their own panel I'd be very appreciative.
Thanks again
AnswerID: 57928

Reply By: Member - Wim (Bris) - Monday, May 10, 2004 at 08:53

Monday, May 10, 2004 at 08:53

I think this a question best resolved verbally face to face.
If you can tell us your 20, maybe someone can demo meter to you.

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AnswerID: 57942

Follow Up By: daddy - Monday, May 10, 2004 at 11:21

Monday, May 10, 2004 at 11:21
I think you're right Wim, trying to describe the situation with my limited (non-existant) knowledge is proving to be very difficult !
I live at Caringbah, Sydney if anyone can provide some tutoring
FollowupID: 319707

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