# How do I know this solar panel properties?

Discussion in 'The Projects Forum' started by TYYang, May 4, 2015.

1. ### TYYang Thread Starter New Member

Apr 3, 2015
18
0
this 28cm x 18cm length
12 inch

i wish to know Watt, voltage, ampere output. where or how can i find these properties ?

Apr 3, 2015
18
0
3. ### MikeML AAC Fanatic!

Oct 2, 2009
5,450
1,066
If there is no data tag, then by measurement. Have you got a DMM and some low voltage lamps (automotive) to use as loads?

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4. ### wayneh Expert

Sep 9, 2010
11,931
2,862
Without a meter, you can estimate the power (wattage) produced by the panel based solely on its size. But you cannot tell what the voltage and current might be.

Once you have a meter, two measurements will tell a lot. In full sun, measure the voltage of the panel with no load. This is the "open circuit voltage". Next, set your meter to its ammeter function and if necessary move the probe to the right socket on your meter. Attach the leads to those of the panel - this will effectively short the panel through the meter. The reading is the "short circuit current".

With several different loads, you could trace out the IV (current versus voltage) curve of your panel. But most panels are similar, so if you get the two measurements above, you can estimate what the entire IV curve looks like. This shortcut may be all you need.

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5. ### Roderick Young Member

Feb 22, 2015
408
168
If a panel does not come with a rating on the plate, it's usually not a very high quality panel. What you can do is hook a voltmeter to it, and point it straight at the sun at noon, and measure the open circuit voltage. Then set your meter on current, and measure the short circuit current. When you multiply those two together, you get a power. Cut that in half (that's called the fill factor, you can look it up), to get an idea of what the panel can really deliver. If it's a quality panel, you might get more, if it's a junk panel, you might get less.

Virtually all commercial panels you can buy are silicon - either crystalline or amorphous. The crystalline ones look like they have multiple small cells in them connected by metal strips. The amorphous, which is an inferior construction, looks like it's made from one solid sheet of something, with a pattern printed on top. Based on size alone, if your panel is crystalline, it should be about 5 watts. Amorphous, 1 watt.

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6. ### TYYang Thread Starter New Member

Apr 3, 2015
18
0
The panel is 5W, 18V, and 0.278A
1.2kg
Thank everyone reply