Testing solar panels

[CyrusL]

Jim and Bob mentioned on their Sunday video getting solar panels from Craigslist but testing them with a multimeter first.  My question is "How do I test if a solar panel is good?" I have a multimeter. Do I just put the panel in the sun and put the probes on the + and - cables and look for 12v?  Is it that easy, or am I looking for something else?

 

[CyrusL]

My message was edited to remove a link to the panels I was looking at.  Sorry for any inconvenience.  Here are the specs that were in the Craigslist ads I was looking at (without the links).

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Several pallets of LG 300 Solar panels in stock for sale

LG offer some of the highest efficiency panels in the market
LG S1CA5 300W: $250 each (BLK/WHT)
*Other LG panels might be available also
NEW, A grade, UL Listed panel with full 25 year warranty
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Up for sales is a Boviet PV Solar Modules Panel 260W Poly Grade A with Black MageFrame BVM6610P-MF compatible with MageMount Rail-less Solar Mounting System from Magerack.

$156.00 each.

High Quality and Reliable Modules
◆ Withstand up to 5400 Pa snow load and 2400 Pa wind load
◆ 1000V DC (UL)
◆ 3 EL inspections per cell/module for defect-free consistency
◆ Type 1 fire-rating per UL 1703 edition 3
◆ High salt and ammonia resistance certified by TUV Rheinland
◆ 0-+5 W guaranteed positive tolerance
◆ Rugged design for long-term durability; passed extended reliability tests

Warranty
◆ 12-year product warranty
◆ 25-year linear power output warranty

Comprehensive Certificates for Products and Management
◆ UL 1703, IEC 61215, IEC 61730, CEC listed, MCS and CE
◆ ISO 9001 for Quality Management Systems
◆ ISO 14001 for Environmental Management Systems
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[DannyB1954]

The 12 volt panels will actually put out more like 21 volts. The voltage has to be higher than the battery in order to charge it. A word of caution on Craigslist panels. Many will not fit on a vehicle. They were made for buildings, and many are not 12 volt. You may need a special controller to make them work.
I did a search with the name given . The price for shipping is not included and that can be substantial. If there is a problem with the panel you will have to pay to ship it back. They are 65" x 40" and are listed on another site as 36 volt. http://www.solardesigntool.com/comp...48/BVM6610M-260/specification-data-sheet.html
They are probably designed for a 24 volt system so you would need a mppt controller to use it with a 12 volt system.

 

[B and C]

Special controller meaning a MPPT controller that will handle the higher voltages of a grid tie panel and not a cheap PWM that will not.

 

[tx2sturgis]

There will be a voltage rating on a label, assuming it hasn't been removed, that will state the VOC (voltage, open circuit), and you should get somewhere near that voltage in full sunlight.

Also, to check current, printed on the label as ISC  (current, short circuit) you simply short the leads of your multimeter (in amps mode) across the leads of the panel. If the panel puts out 10 amps or less, then most normal digital meters will handle that. If the panel is rated at above 10 amps ISC then you will need either a shunt or an amp meter that will handle that current. 

You will see somewhere around or maybe a bit less than the rating....this is normal.

If you get less than say, 80% of the rated voltage or current then that panel probably has some bad cells.

 

[terranaught]

I like to measure the current into a battery, I bought some kyocera panels used, the voltage was good , but they had high impedance breaks in the inter cell bonds, kyocera replaced them no charge, but it was a hassle and I doubt you would get that service from china.