Another solar panel problem

[sailaboutvic]

Friend has two 100w solar panels in parallel one working fine the other wasn't given out any Amps when used my clump on current meter ( which I know works fine ) but the volts was 18v ( tested putting the meter leads over the V+V- open circuit Voltage)
We then decided to test the short circuit current with then panel isolatied as we connect the meter ( set at 10A ) to the lead there was a small spark and all the sudden and the panel spring into life .
Now he finding every morn the same panel doesn't work unless he uses the meter to create the small spark .
Any idea what's going on ?
Panels have been changed around with the same problem happening on the same panel , so it's not the connection .

 

[Iliade]

Probably a loose or dry connection within the panel?

 

[sailaboutvic]

That's possible but why then once we created a spark it will carrying on working all day until it trys to produce power the next day ?

 

[Stemar]

Pure speculation, but maybe the joint warms up a bit with the current passing, which maintains the contact, then cools down at night?