Headline is a bit harsh
If you were going to attempt a record for longest electic flight, powered by the sun, what's wrong with choosing somewhere sunny?
After all, this thing is the first of its kind. It would be a bit daft to test it anywhere else. Leave the more difficult areas for future tests.
When you build a new car, does the prototype immediately start driving at 150mph down the autobahn? Nope. When testing a new rocket, do you launch with an expensive payload? Nope. When testing a new yacht, do you test in force 8 gales? Nope. When testing software, do you first test edge cases? Nope. When testing PARIS do you immediately drop it off a 10 mile high ballon? Nope. When testing Paris, do you immediately go for the.... er, OK, so there is always an exception.