The photoluminescent strip lighting on either side of the aisle is not electrically operated - it is, as you say, charged up by light. You can see it on an overnight flight when all lights are down, but its not overbearingly bright. In addition to the strip floor lighting, there is also emergency lights mounted on the bottom of the overhead lockers shining into the aisle.
All take off's and landing's (with us) are with the ceiling lights on a minimum of "dim" (depending on time of day/night) so, as a result, there is always some charge in the strip lighting for take off and landing - even after a long overnight flight where the lights have been off all night, because the ceiling lights are changed from "off" to "dim" for landing.
I think that makes sense!
