I think they spotted by thru the sub colleter control panels which they will check the current drawage from each section so if the X number of amps is lower than other they will check it closer to make sure which panel is bad and they will find it.
Pas de problme,il marche n'est-ce pas?"(No problem, it works doesn't it?)
SparykinAk: Marc hit the nail basically. The panels were tested at the mfg after assembly as you mentioned. During field testing, the 18 that were 'rejected' were discovered. IMHO, that is a small percentage.
The voltage output from the 18 was 'under performance spec'.
I am curious if anyone has any comments on other install fail/defect panels.
We have installed about 40k Yingli 230 modules in the past 18 months and as stated previously each combiner box is checked and each string's output (Isc and Vmp) are checked and so far all have had a voltage tolerance below 2% and a current tolerance below 3%, well below the rebate threshold.
The biggest issue we've had to date is the care and handling of the modules before, during and after their installation before turning the projects over to the owner, accidents happen and modules aren't cheap.
That's how I do it by comparing with others of a string. There's are several manufacturers who are or were churning out panels a few years ago, Europe was buying up everything they could from the US that was not nailed down