Buying 2nd hand PV panels...how do I test them?

[HedgePig]

I hope the title was self-explanatory but I was hoping someone might give me a few pointers on how to test a handful of used solar panels I am going to see tomorrow?
Aside from the more obvious things I can think of, like cracked glass or rust or damage, how do I safely test each panel to make sure each is actually working? I assume the plug in bit will have a + and a - and I can simply hold a multimeter to them and hold the panel in the sun? Am I going to zap myself?
Do I just measure amps and volts and multiply to get watts? And is there any way I can see how much each panel will have degraded from when it was new?

I am going to assume I can't do any of these things, but certainly I hope some of it is possible. Any suggestions welcome? HP.

 

[Ronski]

You can buy solar panel testers, no idea how reliable they are, but you need optimum sun and the panel at the optimum angle.

 

[Geoff1946]

Maybe make up a test load using car headlamp bulbs?

 

[fourtytwo]

With a multi-meter you can measure VOC & ISC BUT ISC measurements require a suitably rated meter (10A or above) AND extreme caution when making and breaking the circuit as it WILL ARC, fast and hard is the solution, no dainty tickling the connection!

This is in relation to <300W 72 cell panels, if you are contemplating larger than that then you may need a bigger meter and a DC breaker for safety.

 

[binky]

With a multi-meter you can measure VOC & ISC BUT ISC measurements require a suitably rated meter (10A or above) AND extreme caution when making and breaking the circuit as it WILL ARC, fast and hard is the solution, no dainty tickling the connection!

This is in relation to <300W 72 cell panels, if you are contemplating larger than that then you may need a bigger meter and a DC breaker for safety.

ideally a multimeter with an amp clamp, so you can check ampage without your fingers in the way. Multimeter must have DC volts to be any use.

Ideally you also need an irradinace meter, so you can check voltages against strength of sunshine and the appropiate dtata sheet. I used to do this for every panel 10 years ago, but gave up on it about 9 years ago, panels eiither work or they don't.