Don't know, but could speculate that: 50MW is the amount that...

Don't know, but could speculate that:

• 50MW is the amount that should be generated after, say, 20 years operational life? All solar panels degrade over time. I believe First Solar panels degrade at about .5% per year, or 10% over a 20 year life.
• 50MW is the minimum amount that should be generated at the time of year with the lowest solar exposure (June)? Currently it's close to maximum, in June it's probably about 75% of that (ignoring cloud for the moment).

Anyway I'm pleased that the rated output has been reached, and that it looks like the design output is being reached with some contingency margin. Hopefully more to come.