Unlabeled Solar Panel - How do I determine operating characteristics

[bwise]

Three years ago I purchased a portable folding solar panel on eBAY for around $400. The panel came unlabeled and I can't remember the wattage of this panel, I believe it was either 28 or 62 watts and I would like some help in determining which it is and I would also like to double check that is 12volts and not 24volts. I have a multimeter and would appreciate some assistance in what steps I would need to perform to check. Thanks so much. Bob

[Sunking]

All you can do is test the Voltage Open Circuit, and Current Short Circuit readings. That will not tell you exactly what the power rating is, but you can get close with some calculations. Voc x Isc x .75 should get you close.

[bwise]

I know how to measure the open voltage on the DC section of my meter but not that other, how is that accomplished? What would be the readings for 12volt vs 24 volt?

[Sunking]

I know how to measure the open voltage on the DC section of my meter but not that other, how is that accomplished? What would be the readings for 12volt vs 24 volt?

I hestitate to tell you how to measure Isc mainly because I do not know your skill level, and if your meter is even capable of measuring the current.

Isc is done pretty much like the Voc measurement. With the panel disconnected, facing directly into noon day sun on a bright sunny day, you connect your leads to the output leads of th epanel just like the Voc measurement, except the meter is setup to read current. You meter using it in the current mode shorts the panel out allowing you to read the short circuit current.

Assuming the panel is made for 12 volt battery systems, the Voc should be around 22 volts, or 44 volts for a 24 volt system. Isc I cannot tell you without know the wattage of the panel and it is the wildcard and key to finding out the panels power rating. Again assuming this a 12 volt panel and 68 watts you should see around 4.5 to 5 amps.

Two things concern me:

1. Your meter. What make and model is it? If it cannot measure at least up to 10 amps, you are dead in the water.

2. You mentioned this is a fold up panel which makes me think it is a thin film panel, and all the voltages and currents I just gave you are meaningless.