Measuring Solar Panel Performance?
Submitted: Monday, Oct 27, 2008 at 05:50
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gilghana
Hoping for some expert info here... Have acquired a few old solar panels (probly about 12 years old). They are made by 'Eurosolare' which I thinks is Italian, and they are labelled P5A. Now I have googled like hell, and found plenty Eurosolare panels, but no P5A, so I need to try and figure out how to work out their performance? They have been in a dark store for last 8 years or so. So I would be really grateful for any
feedback on how to work out their performance or how good they are?
Cheers,
Gil
Reply By: Member - JohnR (Vic) - Monday, Oct 27, 2008 at 07:48
Monday, Oct 27, 2008 at 07:48
Gil, I am no expert but it would probably help to know the type of panels and dimensions. They are most likely monocyrstalline which are still relatively efficient though the older technology.
Mine are monocrystalline and have glass faces.
Lots rave about particular brands like Unisolar, an American brand but for the surface area they are lower output.
You are going to have to suck and see a bit I think as they ptobably put out 17v so can cause a bit of trouble to batteries sometimes charging for long at that rate. I was told over the weekend though, that the batteries I have - AGM, could take it unhindered, by the manufacturer of the gear.
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Reply By: redeye141 - Monday, Oct 27, 2008 at 08:32
Monday, Oct 27, 2008 at 08:32
Gil,
To
test their output place an amp meter across the terminal and measure current. In the sun without any regulators attached.
This will tell you the output current for the unit if it still works.
Measuring voltage can be misleading.
Redeye
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Follow Up By: hazo - Monday, Oct 27, 2008 at 12:41
Monday, Oct 27, 2008 at 12:41
Redeye 141
An ammeter must be placed in "series" with a load for a reading to be obtained.
A voltmeter across the output "parallel" will tell you the open circuit output voltage, which in turn will tell you if the panel has output.
Obviously the panel must be in full sun to do this.
Physical size is of the panel, is a reasonably good indication of wattage output to be expected from the panel.
Apart from very small panels ( a few Watts) all larger panels should have a suitable sized regulator in their output before attaching to any battery, otherwise you will
cook the battery(s)
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Follow Up By: redeye141 - Monday, Oct 27, 2008 at 13:51
Monday, Oct 27, 2008 at 13:51
Yes Hazo the volt meter will tell you the voltage output but can be misleading. It will give you the O/C voltage but will not pick any high resistance joints or components in the circuit.
To
test the output of a solar panel of unknown quality and output I just place the amp meter across the output of the panel with no load. You will get the full current capability of panel. This will work OK for any panel up to 120W with a standard 10 amp meter.
Have been doing it for years.
Redeye
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Follow Up By: hazo - Monday, Oct 27, 2008 at 16:04
Monday, Oct 27, 2008 at 16:04
No worries mate, I see where you are coming from now.
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Follow Up By: gilghana - Monday, Oct 27, 2008 at 16:45
Monday, Oct 27, 2008 at 16:45
Many thanks guys, all helpful stuff! The panel measures about 1m long by maybe 50cm wide. Will start experimenting now...
Cheers,
Gil
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Follow Up By: Nomadic Navara - Monday, Oct 27, 2008 at 18:52
Monday, Oct 27, 2008 at 18:52
Way back we used to wire a switch in the incoming positive lead from the panel array.The switch was a change over type spring loaded to the button out position. The common connection was wired to the panel, the normally closed one to the regulator and the momentary closed terminal to an ammeter, which was connected to the negative supply lead. To
check the solar array we simply pushed the switch and noted the ammeter reading.
PeterD
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Follow Up By: Member - Mike DID - Monday, Oct 27, 2008 at 23:34
Monday, Oct 27, 2008 at 23:34
The solar panel current when charging a battery will be around 3/4 of the short-circuit current into an Ammeter.
DON'T connect and Ammeter directly across any other power source !!!! Solar Panels are essentially constant current - most other sources are NOT !
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