Wolv, can you clarify - because your statement is somewhat ambiguous - especially when added with your IRC comments - where you said you were getting "around twice the output you should".
When you say "140%", do you mean "you are getting 140% of your expected power" or "140% MORE than your expected power"?
That is to say, if your panels are supposed to be 100 watts, are you getting 140 watts (140% *OF* rated power) or 240 watts (140% *MORE* than rated power).
If the former - and you're getting about 40% more output (140% of rated output) then that's within the upper range I've observed here with "cloud edge" effect under reasonable conditions.
If you're getting about 140% more output, then it sure sounds like someone sold the wrong panels.
What are their physical dimensions, and what is their rated power?
If you work the watts per square metre and it comes out around 15-20% conversion efficiency, then they've sold you the wrong panels. If it comes out around 30-40%, then you have some bizzare local event going on, and you need to find it (and patent it!)