This solar panel is closer to square than most solar panels I've seen, which tend to be very long - length/width ratio perhaps 4 to 6. This looks like only 1.5, and it seems to be located at the end of a long arm. To me this is an unusual configuration - is there something specific about MetOp-A, B, C's operations that require this?
below: Screen shot from 2017-April-19 BBC article about space junk. Presumably this was a random satellite chosen by the author, and does not suggest the configuration is to make it easier to "catch in a big net"!
below: from Gunter's Space Page (Astrium).
below: Astrium Polar Platform (PPF) from Gunter's Space Page.
below: Artists conception of MetOp-A in orbit including fully deployed solar panel on deployment arm, from here:
Once MetOp is in the correct position the solar array, which is on the zenith side of the satellite, is gently deployed to face the Sun. This procedure takes up to 17 minutes and happens in two stages. Initially, the solar array arm rotates 120° up and over. Then the large eight-section panel opens out to face the Sun.
below: MetOp-A, including folded solar panel on deployment arm, from here.
According to Wikipedia MetOp-A is in a sun-synchronous polar orbit with an altitude of 817 km and a local time of ascending node
21:30. I think this means it is always in sunlight, looking down at (roughly speaking) either 9:30AM or 9:30PM local time on the surface.
There is an excellent video about MetOp Instrumentation which also includes some animations of the spacecraft's polar orbit and apparently transverse attitude: